Stratified randomization Randomization technique that ensures a balanced distribution of key covariates or prognostic factors between treatment groups by independent randomization within specific subgroups.

Also: randomization by strata · stratified randomization · stratified allocation · strata-controlled randomization

Mendelian randomization Epidemiological method that uses inherited genetic variants as independent instrumental variables to evaluate the causal effect of a modifiable exposure on a clinical disease.

Also: Mendelian randomization · Mendelian genomic causal study · analysis of genetic instrumental variables · causal Mendelian randomization design

Block Randomization Randomization method designed to maintain comparable sample sizes between study groups throughout recruitment using randomized sequences of predetermined size.

Also: block randomization · block randomization · block randomization · block balanced randomization

Cluster randomization Type of experimental design in which entire groups of individuals, rather than individual people, are randomly assigned to the interventions evaluated.

Also: group randomization · cluster randomization · allocation by study clusters · randomization of entire groups

Cronbach's Alpha Quantitative statistical coefficient used to evaluate the internal consistency and homogeneity of the questions that make up a multidimensional clinical measurement scale or questionnaire.

Also: reliability alpha coefficient · Cronbach consistency · internal consistency of items · inter-item reliability indicator

Cluster analysis Multivariate non-parametric method that consists of automatically grouping a set of data or observations into internal homogeneous and heterogeneous subgroups in a hierarchical or partitioned manner.

Also: cluster analysis · automatic data classification · cluster statistical analysis · systematic data grouping

Cost-benefit analysis Comparative economic evaluation that expresses both the costs of medical interventions and all their health outcomes in common monetary units.

Also: cost-benefit analysis · cost-benefit in health · cost-benefit analysis · purely monetary economic comparison

Cost-utility analysis Specific type of health economic evaluation that compares the costs of therapeutic interventions by evaluating their results in terms of quality and quantity of life.

Also: cost-utility analysis · economic evaluation by QALYs · cost-utility in health · comparison of cost per year of quality of life

Covariance analysis Statistical method that combines simple or multiple linear regression analysis with classical analysis of variance to compare group means, controlling the effect of quantitative confounding variables.

Also: ANCOVA · analysis of variance with covariates · linear control of group variations · mixed model ANOVA-regression

Decision curve analysis Useful advanced quantitative method that evaluates the general clinical net benefit of a diagnostic prediction model at different thresholds of probability of clinical treatment decision in an integrated manner.

Also: DCA · decision curve analysis · clinical evaluation of decision curves · clinical utility decision curves

Budget impact analysis Short-term health economic evaluation that estimates the net financial consequences resulting from the incorporation of a new medical technology in a specific health system.

Also: health budget analysis · financial impact of health technologies · drug budget study · health budget evaluation

Mediation analysis Statistical method used to clarify the causal relationship mechanism between an independent variable and a dependent variable by identifying a third relevant explanatory intermediate variable.

Also: analysis of mediating variables · modeling of mediation pathways · study of the indirect causal effect · causality mediator analysis

Cost minimization analysis Economic evaluation study that is applied to compare therapeutic options with proven equivalent clinical efficacy, identifying the lowest cost alternative.

Also: cost minimization study · minimization of health costs · cost-minimization analysis · analysis of cheaper alternative

Profitability analysis Economic evaluation that compares the direct costs of different therapeutic options with their results measured in physical or clinical units of common effectiveness.

Also: cost-effectiveness analysis · cost-effectiveness study · cost-effectiveness evaluation · economic cost-effectiveness comparison

Sensitivity analysis Verification procedure that evaluates whether the results or conclusions of a study vary substantially by modifying certain key assumptions or by excluding low-quality studies.

Also: analytical robustness tests · methodological sensitivity analysis · sensitivity of results · methodological robustness analysis

Survival analysis Set of statistical procedures to model and analyze the time that passes until an event of interest occurs, such as death, cure or recurrence.

Also: time to event analysis · survival analysis · failure time modeling · parametric survival analysis

Analysis of instrumental variables Statistical method to estimate causal relationships in the presence of unmeasured confounding using a variable that correlates with the exposure but does not directly affect the health outcome.

Also: instrumental variables regression · instrumental causality analysis · confusion control by external variable · instrumental causal inference

Analysis of variance Parametric statistical method used to compare the means of three or more independent groups, determining whether the observed variations are due to chance or real differences.

Also: ANOVA · variance analysis test · variance analysis of one factor · ANOVA parametric model

Factor analysis Multivariate data reduction technique that analyzes the intercorrelations between multiple observed variables to group them and identify latent underlying dimensions or factors that are not directly measurable.

Also: factorial variable reduction · latent factor analysis · latent factor modeling · data reduction factor analysis

Intermediate analysis Statistical evaluation of the efficacy and safety of clinical trial data performed before completing the full recruitment of prespecified participants.

Also: interim analysis · interim evaluation · interim analysis · intermediate evaluation of the trial

Multivariate analysis Set of complex statistical methods used to analyze the simultaneous influence of multiple predictor or explanatory variables on one or more results.

Also: multivariate analysis · multivariate modeling · multivariate multiple regression · multifactorial data analysis

Analysis by protocol Clinical trial analysis strategy that evaluates the results only of patients who completed the assigned treatment in strict accordance with the study protocol.

Also: analysis of compliant cases · per-protocol analysis · pure efficacy analysis · evaluation by treatment protocol

Quality-adjusted life years Health utility measure that combines the remaining life expectancy of patients weighted by an index of their health quality status.

Also: QALY · QALY · quality-adjusted life years · indicator of years of life with quality

Disability-adjusted life years Measure of impact of the global burden of a disease that adds the years of life lost due to premature mortality and those lived with disability or poor health.

Also: DALY · DALY · years of life corrected for disability · indicator of loss of life due to illness

Years of potential life lost Epidemiological measure of the social impact of premature mortality that quantifies the number of years of life that subjects stop living according to the life expectancy of their reference population.

Also: AVPP · YPLL · years of potential life not lived due to premature death · impact of premature population mortality

Decision tree Graphic and quantitative model used in decision analysis that represents temporal sequences of exclusive clinical events and their corresponding probabilities.

Also: decision tree diagram · decisional tree model · clinical tree analysis · sequential decision modeling

Area under the ROC curve Quantitative parameter of the global discrimination performance of a diagnostic test that represents the probability of correctly classifying sick and healthy control subjects.

Also: AUC-ROC · diagnostic discrimination index AUC · diagnostic curve area · AUC diagnostic discrimination metric

Statistical asymmetry Measure that quantifies the lack of symmetry of a data distribution with respect to its mean, indicating whether the values are preferentially grouped on the left or right extreme.

Also: asymmetry bias · distribution asymmetry · Fisher asymmetry · statistical asymmetry coefficient

Ghost authorship Ethically incorrect practice in biomedical publications that consists of deliberately omitting as an author a researcher who has contributed substantially to the design or writing of the manuscript.

Also: ghost authorship · hidden authorship · exclusion of contributory authorship in medicine · unethical exclusion of manuscript author

Honorary authorship Ethically objectionable practice that consists of including as author of a manuscript a professional who has not made any substantial contribution in accordance with the ICMJE criteria.

Also: gift authorship · courtesy authorship · unjustified assignment of authorship · gifted authorship of manuscript

Net clinical benefit Mathematical metric used in decision curve analysis that quantifies the net balance between the benefits of a medical intervention and its possible harms.

Also: net benefit · net clinical utility · weighted net clinical gain · net clinical balance of decision

Bootstrapping Computational resampling method that generates thousands of dummy samples from the original sample data to calculate stable confidence intervals for complex point estimates.

Also: bootstrapping resampling · repeated computational auto-sampling · bootstrap resampling technique · estimation by computational bootstrapping

Quality of evidence GRADE system measure that indicates the degree of certainty that the point estimates of the effects of a treatment are methodologically correct and stable in the face of future research.

Also: level of certainty of the evidence · certainty of GRADE results · quality of GRADE evidence · certainty of GRADE evidence

Endemic channel Graphic representation of the historical distribution of cases of a communicable disease throughout the year used to early detect significant epidemic deviations.

Also: endemic corridor · epidemiological control curve · endemic channel chart · graphic profile of endemic control

Censorship by the right Common type of statistical censoring in survival analysis that occurs when a patient's follow-up time ends before the event of clinical interest is observed.

Also: censorship on the survival right · loss of terminal observation · incomplete survival follow-up · data right truncation

Censorship by the left Situation in survival analysis in which the event of interest or disease has already occurred before the subject begins to be formally observed in the study.

Also: censorship on the left of survival · pre-onset survival event · preoccurrence of study event · data left truncation

Negative likelihood ratio Diagnostic accuracy indicator that indicates how many times it is more likely to obtain a negative test result in a sick patient compared to a healthy control subject.

Also: negative likelihood ratio · LR- · negative probability coefficient for diagnosis · probability ratio of the negative result

Positive probability ratio Diagnostic accuracy indicator that indicates how many times it is more likely to obtain a positive result in a test in sick people compared to healthy controls.

Also: positive likelihood ratio · LR+ · positive probability coefficient for diagnosis · probability ratio of positive result

Kendall correlation coefficient Non-parametric statistical index that measures the intensity and direction of the agreement or rank order correlation between two quantitative or ordinal study variables.

Also: Kendall's tau · tau correlation coefficient · Kendall rank correlation · Kendall tau correlation contrast

Pearson correlation coefficient Parametric index that measures the degree and direction of the linear association between two continuous quantitative scale variables.

Also: r · Pearson linear correlation coefficient · product-moment correlation · Pearson linear correlation

Spearman correlation coefficient Non-parametric measure of the monotonic association between two continuous or ordinal variables based on the ranges of their values.

Also: rho by Spearman · Spearman rank correlation · rho coefficient · non-parametric Spearman correlation

Intraclass correlation coefficient Statistical measure of agreement of continuous variables that evaluates the degree of consistency or reliability between multiple evaluators who measure the same quantitative attribute independently.

Also: CCI · intraclass correlation coefficient · agreement coefficient for continuous variables · inter-rater consistency of continuous variables

Coefficient of determination Proportion of the total variance of the dependent variable that is explained and predicted by the proposed linear regression model.

Also: R-squared · R-squared goodness of fit · R2 coefficient · linear variance adjustment indicator

Cohen's kappa coefficient Non-parametric statistical measure that quantifies the degree of interobserver agreement or diagnostic agreement between two independent evaluators for categorical variables, correcting the expected effect of pure chance.

Also: Cohen's kappa · kappa agreement coefficient · kappa statistic agree · categorical interobserver agreement index

phi coefficient Non-parametric statistical association measure used to quantify the intensity of the correlation between two strictly dichotomous categorical variables.

Also: Pearson's phi · phi contingency coefficient · correlation of two dichotomous variables · binary correlation phi coefficient

Data monitoring committee Group of experts independent of the study in charge of periodically evaluating the safety and effectiveness of the data accumulated during the execution of a clinical trial.

Also: DSMB · data security committee · independent monitoring board · trial data control committee

Financial conflict of interest Ethical situation in which the objectivity or professional judgment of a clinical researcher may be compromised by the presence of relationships or personal financial benefits with study sponsors.

Also: economic conflict of interest · research financial relationships · financial biased sponsorship · economic bias in clinical research

CONSORT Consortium International initiative that provides guidelines and a standardized checklist to improve the quality and transparency of randomized clinical trial reporting.

Also: CONSORT guidelines · CONSORT statement · clinical trial publication standard · CONSORT norm

Bonferroni correction Conservative mathematical adjustment of significance that consists of dividing the alpha significance level by the total number of hypothesis tests or multiple comparisons carried out to control type I error.

Also: Bonferroni adjustment · Bonferroni multiplicity correction · conservative method of multiple comparisons · Bonferroni linear significance correction

Akaike information criterion Metric for evaluating and comparing statistical models that balances the goodness of fit of the proposed model against its general mathematical complexity.

Also: AIC · Akaike indicator · AIC selection information criterion · Akaike estimator of fit quality

Bayes information criterion Mathematical measure of comparison and selection of statistical models that more severely penalizes the complexity of the model based on the total size of the general sample.

Also: BIC · Bayesian information criterion BIC · Bayesian selection indicator · Bayes estimator of fit quality

Crossover design Clinical trial design in which each participant consecutively receives two or more treatments in different periods, with the patient serving as his or her own control.

Also: crossover clinical trial · cross design · crossover intervention study · crossover experimental design

Quartile Any of three values that divide an ordered distribution of numerical data into four exactly equal parts, each representing twenty-five percent of the observations.

Also: statistical quartile · division by quartiles · twenty-five percentile cutoff · twenty-five percent cuts

Kurtosis Measurement of the concentration and shape of the frequency distribution of statistical data, which describes the degree of pointing or flattening of the resulting curve compared to the standard normal distribution.

Also: pointing coefficient · distribution acuity · statistical scoring · frequency distribution form

Cost-effectiveness acceptability curve Probabilistic graph that shows the probability that a health intervention is considered cost-effective for different maximum willingness-to-pay thresholds of the reference health system.

Also: CEAC · probabilistic cost-effectiveness curve · incremental economic acceptability of health · probabilistic economic viability profile

Kaplan-Meier curve Non-parametric estimator of the survival function that shows the cumulative probability that an event has not occurred over the continuous follow-up time.

Also: Kaplan-Meier estimator · Kaplan-Meier survival graph · cumulative survival curve · non-parametric survival profile

d by Somers Asymmetric measure of non-parametric association for ordinal variables that evaluates the degree of consistency in the ordering of observations between two continuous or ordinal variables.

Also: Somers d coefficient · Somers asymmetry · Somers' d statistic for ordinal variables · Somers asymmetric d index

Decile Any of the nine values that divide an ordered distribution of numerical observations into ten equal parts of ten percent each sequentially.

Also: statistical decile · cutoff percentile of ten · decilar division · ten percent cuts

Declaration of Helsinki International document of ethical principles for medical research on human beings, prepared and continually updated by the World Medical Association.

Also: Helsinki ethical principles · Helsinki guidelines · Helsinki code of ethics · Helsinki international ethical guidelines

MOOSE Statement Set of methodological reporting guidelines designed to improve the transparency of meta-analyses of purely observational studies in clinical epidemiology.

Also: MOOSE guidelines · MOOSE reporting standards · MOOSE checklist · MOOSE reporting standard

PRISM Statement Methodological guide consisting of a checklist and a flow chart designed to optimize the writing and transparency of publications of systematic reviews and meta-analyses.

Also: PRIMA guidelines · PRISMA statement · PRIMA publication protocol · PRIMA publication standard

STROBE statement Set of standardized guidelines and recommendations aimed at improving the rigor, clarity and transparency of reporting of observational cohort, case-control and cross-sectional studies.

Also: STROBE guidelines · STROBE guide · STROBE publication rules · STROBE epidemiology standard

Absolute deviation from the median Robust measure of variability and dispersion that represents the median of the absolute deviations of each individual data in the sample with respect to the general median.

Also: MAD · median absolute deviation · robust mean deviation · robust median variability

Deviation from clinical protocol Minor modification of the methodological guidelines pre-specified in the protocol of a clinical trial that occurs unintentionally and does not seriously compromise patient safety.

Also: minor protocol variation · involuntary deviation from guidelines · minor protocol incident · non-critical protocol deviation

Standard deviation Measure of statistical dispersion that indicates the average deviation of individual values with respect to the mean of their own data distribution.

Also: standard deviation · standard deviation · sample sigma · typical data dispersion

Stem and leaf diagram A graphical representation format that organizes a set of quantitative numerical data so that each value is divided into a stem root and an individual leaf end.

Also: stem and leaf plot · statistical stem and leaf plot · arrangement of stems and leaves · numerical stem and leaf diagram

Minimal clinically important difference Smallest clinical change in health status or score on an outcome variable that patients or physicians perceive to be truly important or beneficial.

Also: DCIM · MCID · minimal relevant clinical difference · minimal clinically relevant change

Cook Distance Statistical influence indicator that measures the effect that the elimination of a particular case has on the overall estimates of the parameters of a linear regression model.

Also: Cook's distance · Cook's influence measure · Cook regression outliers indicator · Cook's individual influence

Binomial distribution Discrete probability distribution describing the number of successes when performing a fixed number of independent Bernoulli trials with a constant probability of success.

Also: repeated Bernoulli distribution · binomial trial distribution · binomial model · discrete binomial distribution

Chi-square distribution Positive, asymmetric continuous probability distribution describing the sum of the squares of independent standard normal random variables.

Also: Pearson distribution · chi-square distribution · chi-square distribution · chi-square model

Gaussian distribution Continuous and symmetrical probability distribution around its mean, characterized by its classic bell shape in which the mean, median and mode coincide.

Also: normal distribution · Gauss bell · normal frequency curve · Gaussian probability model

Poisson distribution Discrete probability distribution that expresses the probability that a given number of events will occur in a fixed interval of time or space, under a constant average rate of occurrence.

Also: Poisson's law · rare event distribution · Poisson model · discrete Poisson distribution

Weibull Distribution Versatile continuous probability distribution widely used in survival analysis to model failure times that exhibit increasing, decreasing, or constant hazard rates.

Also: Weibull probability model · Weibull survival distribution · Weibull reliability curve · Weibull distribution of temporal faults

Leptokurtic distribution Statistical frequency distribution that presents a high bias with respect to the normal due to a large concentration of data in the central area and thicker tails.

Also: high kurtosis curve · high targeting distribution · leptokurtosis · pointed frequency distribution

Mesokurtic distribution Statistical frequency distribution that presents a pointing level identical or homologous to that of the classical Gaussian normal distribution.

Also: normal kurtosis curve · mesokurtosis · normal Gaussian pointing · standard pointing distribution

Platykurtic distribution Probability distribution that is characterized by being flatter and flatter than the normal distribution, indicating a more homogeneous dispersion of the data and less pronounced tails.

Also: low kurtosis curve · flat distribution · platykurtosis · flattened frequency distribution

Student's t distribution Continuous probability distribution that arises when estimating the mean of a normally distributed population when the sample size is small and the population standard deviation is unknown.

Also: t distribution · t Student · Student's t curve · probability t model

Data Dredge Methodologically incorrect practice that consists of carrying out multiple statistical analyzes in an exploratory and indiscriminate manner to force the detection of fictitious significant relationships.

Also: data dredging · data fishing · exploratory analysis p-hacking · indiscriminate search for significance

Drag effect Persistence of the therapeutic or biological effect of the treatment administered in the first period of a crossover trial during the evaluation period of the second treatment.

Also: carryover effect · residual effect of treatment · effect persistence bias · interperiod drag effect

Interaction effect Statistical situation in which the joint effect of two or more predictor variables on the outcome variable is different from the sum of their independent individual effects.

Also: statistical synergy · covariate multiplier effect · multifactor statistical interaction · interaction of regression factors

Hawthorne Effect Modification of the behavior or performance of subjects participating in a clinical study due to the simple fact of knowing that they are being actively observed.

Also: observer bias over participant · observation behavioral reactivity · clinical observation effect · reactivity to the test

Nocebo effect Appearance of adverse effects or worsening of clinical symptoms due to the patient's negative expectations regarding the administration of an inert substance or placebo.

Also: nocebo response · adverse effect of expectations · adverse reactions due to placebo · psychogenic worsening due to expectations

Period effect Systematic variation observed in the responses of participants in a crossover trial due to the passage of time or seasonal changes independent of the treatment administered.

Also: period bias · temporal influence in crossover design · chronological effect of the essay · variation by test moment

Community trial Population-based experimental intervention study where the unit of assignment and application of preventive health treatment are complete communities of subjects grouped together.

Also: population clinical trial · experimental community study · community health intervention · community intervention trial

Type I error Error committed in a hypothesis test by rejecting the null hypothesis when it is actually true in the source population.

Also: alpha error · statistical false positive · incorrect rejection of the null hypothesis · alpha significance error

Type II error Inference error that occurs when the null hypothesis is not rejected, being false in the real population, failing to detect an existing effect.

Also: beta error · statistical false negative · incorrect acceptance of the null hypothesis · beta power error

Standard error of the mean Measure that quantifies the expected variability of the sample mean when estimating the true population mean from repeated samples of equal size.

Also: SEM · sample standard error · standard deviation of the distribution of means · mean estimation error

Interval scale Quantitative scale for measuring variables where the differences between the values are equal and quantifiable, but zero is arbitrary and does not indicate the absence of the measured property.

Also: interval level · relative temperature scale · equal interval scale · measuring scale with arbitrary zero

Jadad Scale Structured scale that quickly evaluates the methodological quality of clinical trials based on the description of blinding, randomization and reporting of losses.

Also: Oxford scale of quality · Jadad's score · Jadad test of methodological quality · Jadad scale of test validity

Ratio scale Quantitative measurement scale that has all the properties of the interval scale along with a true absolute zero that represents the complete absence of the measured characteristic.

Also: proportion scale · radius scale · absolute zero scale · parametric ratio measurement

Nominal scale Most basic qualitative level of measurement where data is classified into mutually exclusive and exhaustive categories without any inherent order or hierarchy between them.

Also: nominal measurement level · nominal categorical scale · nominal rating · measurement of nominal attributes

Ordinal scale Qualitative level of measurement where the data are classified into categories that have a logical order, sequence or hierarchy, although the exact difference between the values is not quantifiable.

Also: ordinal measurement level · rank scale · ordinal hierarchy · graduated ordinal classification

Inferential statistics Branch of mathematical statistics that deals with deducing, estimating and generalizing conclusions about the properties of a population of interest based on the analysis and observation of a representative sample.

Also: data inference · predictive statistics · inductive mathematical data methods · inductive statistical inference

Non-parametric statistics Set of statistical tests that do not require rigid distribution assumptions for the study variables, useful for highly asymmetric distributions or qualitative measurement scales.

Also: free distribution statistics · assumption-free non-parametric tests · non-parametric statistical contrasts · non-parametric data analysis

Parametric statistics Set of statistical inference methods that assume that the study variables follow a probability distribution with known and specific parameters, such as classical Gaussian normality.

Also: parametric statistical methods · classical parametric tests · distributive inference of parameters · parametric data analysis

Test statistic Numeric value calculated from the sample data that is used in the hypothesis test to evaluate consistency with the null hypothesis.

Also: contrast statistical value · result of the statistical test · contrast statistic · mathematical significance indicator

I-squared statistic Measure of heterogeneity in meta-analysis that indicates the proportion of the variability in estimates of therapeutic effect between studies that is due to real differences and not mere chance.

Also: I-squared heterogeneity index · inconsistency indicator of meta-analysis results · I2 statistics · percentage of heterogeneity in meta-analysis

PICO search strategy Structured format to formulate precise clinical research questions in evidence-based medicine, dividing the problem into Patient, Intervention, Comparison and Outcome.

Also: PEAK format · PICO structured clinical question · PEAK search breakdown · clinical question formulation framework

Stratification Analytical or methodological design technique that consists of grouping subjects into homogeneous subgroups according to a confusion variable to control its effect.

Also: stratified analysis · stratified design · strata control · analytical stratification of confusion

Cross-case study Research design in which each patient serves as his or her own comparison control by analyzing whether an unusual exposure immediately before the event is associated with the development of the event.

Also: case-crossover study · individual cross-case study · temporal retrospective self-comparison design · individual cross-case design

Nested case-control study Observational epidemiological design in which cases and controls are selected retrospectively within a well-characterized defined cohort with previously recorded exposure data.

Also: case-control design nested in a cohort · nested case-control study · intra-series cases and controls · nested case-control research

Prospective cohort study Analytical observational design where healthy subjects are initially selected, classifying them according to their exposure factors, and continuously monitoring them over time into the future to observe the appearance of diseases of interest.

Also: prospective cohort · prospective follow-up study · prospective cohort study · prospective health cohort research

Retrospective cohort study Analytical observational design in which the identification of exposure and monitoring of subjects to identify health outcomes are carried out based on historical records from the past.

Also: retrospective cohort · historical cohort study · retrospective cohort study · registry-based cohort research

Synthetic control study Observational statistical method that evaluates the impact of an intervention by creating a virtual comparison group through a weighted combination of multiple non-optimally exposed control units.

Also: synthetic control cohort · synthetic control method · synthetic comparison analysis · observational synthetic control design

Equivalence study Clinical trial designed to demonstrate that a new treatment is not substantially better or worse than an existing standard treatment within previously defined limits.

Also: equivalence test · therapeutic equivalence test · clinical equivalence design · comparative equivalence study

Non-inferiority study Clinical trial intended to demonstrate that a new treatment is not clinically worse than the active comparator treatment by a prespecified margin.

Also: non-inferiority trial · non-inferiority study · therapeutic non-inferiority design · non-inferiority clinical study

Diagnostic accuracy study Clinical research design that evaluates the performance of a new diagnostic test by directly and blindly comparing its results against an independently established reference standard.

Also: diagnostic test validation study · diagnostic accuracy test · validity evaluation of clinical test · diagnostic accuracy investigation

Case series study Detailed and observational description of the clinical characteristics, evolutionary course and outcomes of a group of patients who present the same disease or common treatment of interest.

Also: clinical series · report of multiple cases · descriptive study of clinical cases · grouped case report

Study of interrupted time series Quasi-experimental methodological design that analyzes the effect of a health intervention by comparing multiple measurements repeated over time before and after applying said intervention.

Also: interrupted time series design · time trend interruption analysis · temporal quasi-experiment · analytical study of interrupted time series

Superiority study Classic clinical trial whose main objective is to demonstrate in a statistically significant way that the new therapeutic intervention is more effective than the comparator.

Also: superiority test · superiority trial · clinical superiority test · classic superiority design

Ecological study Observational design in which the unit of analysis is groups or geographic populations of individuals instead of individual subjects, analyzing aggregate data.

Also: correlational study of populations · aggregative study · analysis of aggregate population data · population ecological correlation

Cross-sectional study Descriptive and analytical observational design in which the exposure and the outcome of interest are measured simultaneously in the study subjects at a single point in time.

Also: prevalence study · cross-sectional health survey · cross-sectional study · instant observational research

Variance inflation factor Descriptive statistical index that quantifies the magnitude by which the variance of an estimated regression coefficient increases due to the presence of collinearity with other predictor variables.

Also: VIF · multicollinearity indicator · regression variance inflation measure · VIF collinearity index

Ecological fallacy Statistical interpretation bias that occurs when erroneously deducing individual-level causal relationships from associations observed at the level of aggregate groups or ecological populations.

Also: ecological bias · aggregation fallacy · ecological inference error · systematic group attribution error

Test-retest reliability Measurement of the temporal stability of a clinical evaluation instrument when applied identically to the same group of stable patients at two different moments in time.

Also: reliability of repeated measurements · temporal consistency of test · test-retest stability · stable measurement consistency

Fraction attributable to exposed Proportion of cases of a disease in the exposed group that can be directly attributed to the presence of the evaluated risk factor.

Also: percentage of attributable risk in exposed · etiological fraction in exposed · impact of the risk factor on those exposed · attributable exposure fraction

Strength of the recommendation GRADE system indicator that expresses the degree of confidence that the clinical benefits of a medical intervention substantially exceed its possible associated harms.

Also: clinical recommendation grading · therapeutic guideline strength · grade of recommendation GRADE · GRADE recommendation intensity

Cumulative incidence function Statistical estimator in survival analysis that calculates the net probability of suffering a specific event of interest in the presence of concurrent competitive events.

Also: CIF · cumulative incidence function · cumulative incidence of competitive events · net probability of competitive event

Survival function Mathematical expression that indicates the cumulative probability that an individual will survive beyond a given follow-up time without experiencing the event of interest.

Also: theoretical survival curve · cumulative survival function · temporary survival probability · mathematical survival profile

g by Hedges Standardized effect size index used to quantify the difference between the means of two groups, which includes a bias correction for small sample sizes.

Also: Hedges effect size · Cohen's d Hedges correction · g coefficient · Hedges adjusted standardized estimate

Directed acyclic graph Visual flowchart that describes asymmetric causal relationships between variables using nodes and unidirectional arrows to identify and guide the control of confounding variables.

Also: acyclic causal diagram · structured causality graph · causal graphical modeling of confusion

Bland-Altman graph Two-dimensional scatter plot that analyzes the degree of agreement of two different continuous measurement methods or instruments by plotting their differences against their individual averages.

Also: Bland-Altman agreement diagram · concordance dispersion analysis · continuous agreement difference graph · Bland-Altman graph

Forest graph Detailed graphical representation of the results of a meta-analysis showing the point estimates and confidence intervals for each individual study along with the synthesized overall effect.

Also: forest plot · forest diagram · forest plot · evidence synthesis representation

Box and whisker plot Non-parametric two-dimensional graphical representation that visually describes the symmetry, median, dispersion, quartiles and outliers of a quantitative variable.

Also: boxplot · five number box plot · statistical box plot · five number summary representation

Funnel Chart Two-dimensional scatterplot plotting the effect size of studies against a measure of their precision, used to visually assess publication bias.

Also: funnel plot · precision funnel chart · funnel diagram in meta-analysis · publication bias scatterplot

Galbraith graph Scatter plot representation that simultaneously evaluates the statistical significance of the effect of individual studies in a meta-analysis and their overall heterogeneity.

Also: Galbraith plot · radial scatter plot · Galbraith heterogeneity diagram · Galbraith radial graph

Cochrane risk of bias tool Structured and standardized instrument to evaluate the internal validity of randomized clinical trials by identifying the risk of bias in multiple domains of the study.

Also: RoB tool · Cochrane risk of bias scale · Cochrane evaluation of internal validity · Cochrane bias test

QUADAS-2 Tool Standardized instrument for evaluating methodological quality and risk of bias in diagnostic accuracy studies included in formal systematic reviews.

Also: QUADAS-2 scale · diagnostic test study quality tool · risk of bias test in diagnosis · QUADAS-2 diagnostic precision instrument

Heteroskedasticity Circumstance in a linear regression model where the variance of the residuals or errors is not constant across the different values of the predictor variables.

Also: non-homogeneity of residual variances · heteroscedasticity · non-constant error variance · variable residue dispersion

Statistical heterogeneity Variability in the treatment effects observed between the different individual studies included in a meta-analysis, which exceeds that expected by mere random sampling.

Also: heterogeneity of results · inter-study variability · heterogeneity in meta-analysis · effect size inconsistency

Methodological heterogeneity Variability in the results of the studies of a meta-analysis due to significant differences in design, methodological rigor, blinding or general quality between the trials analyzed individually.

Also: methodological inconsistency · inter-study design variability · heterogeneous design bias · methodological disparity between studies

Alternative hypothesis Proposition that affirms the presence of a real difference, effect or association between variables, which is accepted if the null hypothesis is formally rejected.

Also: research hypothesis · real effect hypothesis · hypothesis of presence of association

Null hypothesis Statement of no difference, no effect or absence of association between the variables evaluated in a population that is subjected to hypothesis testing.

Also: hypothesis of no effect · base hypothesis of no difference · basal equality assertion

Homoscedasticity Fundamental assumption of classical linear regression models in which the variability of the errors is constant in all predictor observations.

Also: homogeneity of error variance · homoscedasticity · homoscedastic assumption · constant variance of residuals

Multiple imputation Advanced estimation method to handle missing data in a sample set by replacing each missing value with several plausible values based on probabilistic and sample covariance models.

Also: repeated probabilistic imputation · multiple missing data replacement · probabilistic void modeling · multiple imputation technique

Simple imputation Substitution procedure that replaces missing or empty data from a sample set with a single estimated numerical value, such as the mean of the corresponding variable.

Also: univariate replacement of missing data · single value imputation · simple replacement of voids · simple replacement of missing data

Inconsistency in network meta-analysis Significant statistical discrepancy detected in a network meta-analysis between the evidence of effectiveness obtained by direct comparisons of trials and indirect comparisons based on mathematical models.

Also: network statistical inconsistency · direct-indirect discrepancy · network inconsistency bias · direct-indirect network divergence

Youden Index Global diagnostic measure that evaluates the ability of a test to correctly classify subjects by adding sensitivity and specificity and subtracting one from said value obtained.

Also: J by Youden · Youden diagnostic performance coefficient · Youden diagnostic agreement index · Youden index of test effectiveness

Critical reading Systematic and rigorous evaluation of the methodological validity, clinical results and practical applicability of published medical literature to inform informed therapeutic decisions.

Also: critical reading of evidence · critical evaluation of medical literature · methodological analysis of scientific articles · systematic evaluation of clinical validity

Bland-Altman agreement limits Range of numerical values that defines the expected variation interval for the difference between two instruments or evaluators that measure the same quantitative variable.

Also: Bland-Altman interval of agreement · agreement variation limits · limits of inter-method agreement · Bland-Altman 95 percent range of agreement

Gray literature Scientific documents, technical reports, postgraduate theses or conference proceedings that are produced and distributed through channels other than commercial publishers and traditional indexed journals.

Also: non-indexed publications · unconventional literature · technical research reports · informal academic publications

Non-inferiority margin Maximum prespecified clinical difference that a new drug can have compared to the active control to consider that its efficacy is not inferior.

Also: non-inferiority delta · non-inferiority limit · statistical tolerance margin · non-inferiority acceptance limit

Arithmetic mean Quantitative measure of central tendency obtained by adding all the observed values of a sample and dividing the result by the total number of observations.

Also: arithmetic average · sample mean · average data · sample mean value

Medium Value that occupies the central position in a set of data ordered from smallest to largest, dividing the distribution exactly into two equal fifty percent parts.

Also: fifty percentile · sample central value · statistical median · fifty percent cut of the sample

Cumulative meta-analysis Type of meta-analysis in which individual clinical trials are integrated sequentially and chronologically according to their publication date to evaluate when significance is reached.

Also: cumulative sequential meta-analysis · temporal cumulative evidence analysis · chronological evidence synthesis · cumulative sequential meta-analysis

Network meta-analysis Advanced extension of traditional meta-analysis that allows multiple alternative health interventions to be compared simultaneously by combining direct evidence from trials and indirect evidence using a common comparator.

Also: network meta-analysis · multiple indirect network comparisons · meta-analysis of multiple comparisons of treatments · synthesis of multiple evidence of treatments

Meta-regression Extension of meta-analysis that uses regression models to explore whether the characteristics of the included studies influence the variability of the overall effect size.

Also: meta-analysis regression · meta-regression analysis · study level regression · inter-study heterogeneity modeling

Qualitative meta-synthesis Rigorous systematic integration of findings from multiple independent qualitative studies on the same clinical phenomenon of specific interest.

Also: structured qualitative meta-synthesis · systematic qualitative review · synthesis of qualitative evidence · qualitative integrative synthesis

Direct adjustment method Epidemiological statistical procedure that applies the specific mortality rates of different groups to a standard reference population to eliminate the influence of confounding variables.

Also: direct standardization of rates · direct rate adjustment · direct method of standardization · direct mortality normalization

Indirect adjustment method Epidemiological standardization technique used to compare mortality rates when data from specific subgroups are too small or unstable in the directly evaluated population.

Also: indirect standardization of rates · indirect rate adjustment · indirect standardized mortality method · indirect standardization of mortality rates

DerSimonian-Laird method Statistical estimation technique commonly used in random effects meta-analysis to quantify the variability between individual studies analyzed together.

Also: DerSimonian and Laird estimate · DerSimonian-Laird random effects weighting · DerSimonian-Laird inter-study method · classical DerSimonian-Laird random effects estimator

Mantel-Haenszel method Fixed effects meta-analysis statistical technique used to combine in a weighted manner point estimates obtained from multiple independent two-by-two contingency tables directly.

Also: Mantel-Haenszel weighting · Mantel-Haenszel fixed effects estimator · Mantel-Haenszel method of meta-analysis · Mantel-Haenszel adjustment for fixed effects

Crop and fill method Statistical simulation procedure in meta-analysis that detects the asymmetry of a funnel plot and adds missing theoretical studies to recalculate the bias-free global effect estimate.

Also: trim and fill method · Duval and Tweedie funnel imputation method · meta-analysis symmetric fitting technique · readjustment due to Duval and Tweedie asymmetry

Delphi Method Systematic qualitative and quantitative technique of structured consultation with a panel of independent experts through successive rounds of anonymous interactive questionnaires to reach a consensual clinical consensus.

Also: Delphi consensus technique · structured Delphi study · interactive Delphi method · systematic Delphi consensus technique

Fashion Qualitative or quantitative measure of central tendency that represents the value, category or score that occurs most frequently in a data distribution.

Also: most frequent value · modal score · predominant value · statistical mode

Random effects model Meta-analysis approach that assumes that the true therapeutic effect varies randomly between different studies due to methodological factors or the population selected in advance.

Also: random-effects model · meta-analysis of combined inter-study variability · random effects variability model · DerSimonian-Laird random effects model

Fixed effects model Statistical meta-analysis approach that assumes that the true treatment effect evaluated is identical in all included studies, attributing any observed variation to internal sampling randomness.

Also: fixed-effect model · exclusive intra-study variability meta-analysis · parametric model of constant effects · fixed variance effects model

Markov model Statistical modeling tool used in pharmacoeconomics to represent long-term health processes characterized by recurrent transitions between mutually exclusive clinical states.

Also: Markov chain in health · Markov simulation analysis · stochastic modeling of transition states · transitional Markov model

Cox proportional hazards model Semiparametric regression model that evaluates the relationship between multiple covariates and the time to an event, assuming that the effect of the covariates is constant over time.

Also: Cox regression · Cox model · multivariate Cox survival analysis · semiparametric Cox regression

Generalized linear model Flexible mathematical framework that extends classical linear regression to allow modeling of response variables that have non-normal error distributions using a fixed mathematical link function.

Also: GLM · multifactor generalized linear model · generalized linear regression · generalized statistical regression framework

Effect modification Epidemiological phenomenon in which the magnitude of the effect of an exposure on a health outcome varies significantly depending on the values of a third external control variable.

Also: epidemiological interaction · association strength modification · bias due to presence of effect modifier · effect variation by subgroups

Simple random sampling Probabilistic selection method where each individual in the population has an equal and independent opportunity to be included in the study sample.

Also: simple random selection · simple equiprobabilistic sampling · simple sample randomization · pure randomized sampling

Snowball Sampling Non-probabilistic sampling method in which the initial participants recruit other eligible subjects for the study, useful for studying hard-to-reach populations.

Also: network sampling · reference chain sampling · snowball sampling · selection by successive recommendation

Cluster sampling Probabilistic sampling method in which the population is divided into heterogeneous groups and several complete clusters are randomly chosen to make up the sample.

Also: cluster sampling · geographic group sampling · cluster sampling · sampling by grouped units

Systematic sampling Probability sampling technique in which elements are selected from the population at fixed regular intervals defined by a constant elevation coefficient.

Also: interval sampling · systematic selection sampling · systematic randomization · systematic uniform selection

Systematic random sampling Probability sampling variant in which the first element is randomly selected and then continues to be chosen sequentially at pre-established regular intervals from the list.

Also: sampling by ordered steps · systematic sampling with random start · randomized systematic selection · random sequential sampling

Multicolinearity Situation in a multiple regression analysis where two or more independent variables present a strong mutual linear correlation, making individual estimation of their effects difficult.

Also: multiple collinearity · redundancy of predictors · regression collinearity · linear dependence between predictors

Altman nomogram Linear calculation graph that helps quickly visually determine the sample size required in studies comparing means or proportions based on the desired power.

Also: Altman sample size nomogram · Altman calculation scale · Altman power graph · Altman graphical sample calculus

Fagan's name Linear calculation graph that allows you to quickly visually correlate pretest probability with likelihood ratios to estimate the resulting posttest probability.

Also: Fagan diagnostic nomogram · Fagan diagnostic probability scale · Fagan likelihood nomogram · Bayesian Fagan conversion graph

Number needed to damage Therapeutic safety index that indicates the number of patients who need to receive a treatment for one additional patient to suffer an adverse event derived from the intervention.

Also: NNH · number needed to harm · number necessary to harm · therapeutic damage index

Hide assignment Design procedure in clinical trials that prevents researchers or patients from knowing the group assigned to the subject before definitive inclusion in the study.

Also: allocation concealment · assignment hiding · prevention of selection bias in allocation · random assignment shield

Diagnostic odds ratio Indicator of the precision of a diagnostic test obtained from the quotient of the probability of obtaining a true positive result and the probability of a false positive.

Also: DOR · diagnostic odds ratio · Youden diagnostic odds ratio · diagnostic possibilities index

Statistical warhead Graphic representation of a cumulative frequency distribution that progressively shows the proportion of data located below certain specific numerical values.

Also: cumulative frequency graph · cumulative frequency curve · distribution warhead · cumulative graphical representation

Outlier Sample observation that deviates so extreme from the rest of the sample measurements that it raises suspicions of having been generated by a different recording or measurement mechanism or error.

Also: outlier value · aberrant data · unusual extreme value · extreme anomalous observation

Washing period Intermediate phase of a crossover clinical trial in which all active treatment is suspended to ensure complete elimination of the initial drug before starting the next one.

Also: washout period · therapeutic deprivation interval · drug clearance period · drug clearance interval

Active placebo Pharmacologically inactive substance designed to mimic the physical side effects or sensations of the experimental treatment, reducing accidental unblinding of patients.

Also: mimicry placebo · physical effect control · active control placebo · effect emulation placebo

Cost-effectiveness plan Two-dimensional graphic representation of four quadrants where the results of incremental cost and incremental effectiveness obtained by medical treatments under evaluation are visually located.

Also: economic evaluation plan · two-dimensional cost-effectiveness graph · incremental economic health plan · incremental cost-effectiveness representation

Population with security analysis Subgroup of participants in a clinical trial who received at least one dose of the treatment under evaluation and from whom data were collected for the analysis of adverse effects experienced.

Also: safety population · clinical safety population · sample for trial adverse events · side effects evaluation population

Modified intention-to-treat population Definition of subgroup analysis in clinical trials that justifiably excludes certain randomly assigned participants from the overall results based on baseline dose or objectivity criteria.

Also: mITT · modified intention-to-treat · adjusted intention-to-treat analysis · modified ITT population of efficacy

Population by protocol Subset of participants from a randomized clinical trial who completed the study in strict compliance with all guidelines, clinical visits, and treatment specifications of the research protocol.

Also: PP · per-protocol population · sample of strict compliance with testing · population complying with research protocol

Statistical power Probability of correctly rejecting the null hypothesis when there is a real effect or difference in the population, equivalent to one minus the beta error.

Also: statistical power · power of the test · statistical power · probability of detecting a real effect

Weighting by the inverse of the probability of treatment Balancing method based on the propensity score that assigns weights to each observation to correct confounding bias in observational studies emulating random assignment.

Also: IPTW · IPTW confusion weighting · inverse propensity adjustment · IPTW propensity weighting

Pre-registration of studies Advance public declaration of the design, hypothesis and statistical analysis plan of an investigation before the start of data collection, aimed at avoiding publication and selective reporting bias.

Also: methodological pre-registration · previous registration of the study protocol · advance data analysis statement · prospective registration of research protocol

Period prevalence Proportion of the population that presents the disease of interest at any time within a specific chronological interval determined.

Also: interval prevalence · period cumulative prevalence rate · temporal prevalence · proportion of period patients

Point prevalence Proportion of individuals in a defined population who present a disease or characteristic of interest at a single, specific time point.

Also: point prevalence · prevalence at the moment · instantaneous prevalence rate · proportion of specific patients

Post-test probability Estimated probability that the patient suffers from the disease of interest once the positive or negative result of the diagnostic test used is known.

Also: posttest probability of illness · a posteriori probability of diagnosis · final post-test probability · final diagnostic probability

Pretest probability Probability that a patient presents the disease of interest before performing the corresponding diagnostic test, estimated purely clinically and based on prevalence.

Also: a priori probability of disease · pretest clinical prevalence · baseline diagnostic probability · pretest diagnostic probability

Benjamini-Hochberg procedure Multiplicity corrective statistical method that controls the expected proportion of false discoveries in simultaneous multiple hypothesis testing analyzes of large volumes of data.

Also: Benjamini-Hochberg FDR control · probabilistic FDR fitting · Benjamini-Hochberg adjustment · Benjamini-Hochberg correction for multiplicity

Bilateral test Hypothesis testing where the rejection region of the null hypothesis is divided into both ends of the test probability distribution.

Also: two-tailed test · bilateral test · bidirectional hypothesis testing · two-tailed statistical test

Begg's test Non-parametric hypothesis testing that evaluates the presence of publication bias by analyzing the Kendall rank correlation between the estimated effects and their sample variances.

Also: Begg test · Begg and Mazumdar correlation · non-parametric Begg method · Begg rank correlation test

Pearson's chi-square test Non-parametric statistical test that evaluates the existence of a significant association between two qualitative variables by analyzing the discrepancy between observed and expected frequencies.

Also: chi-square test of independence · Pearson chi-square test · chi-square association · chi-square independence test

Cochran-Armitage test for trends Statistical test of proportions designed to evaluate whether there is a progressive linear association between an ordinal explanatory categorical variable and a binary health outcome.

Also: Cochran-Armitage test · proportion trends test · Cochran-Armitage contrast · Cochran-Armitage linear trend test

Egger's test Quantitative linear regression method used to statistically evaluate the asymmetry of a funnel plot, indicating the possible presence of significant publication bias.

Also: Egger asymmetry regression · Egger's test of publication bias · linear Egger bias contrast · Egger's analysis of asymmetry

Hypothesis testing Statistical inference procedure used to decide whether sample data provide sufficient evidence to reject a claim about a population parameter.

Also: hypothesis contrast · hypothesis test · statistical significance test · data significance analysis

Kruskal-Wallis test One-way non-parametric statistical test that evaluates whether there are significant differences between the ranges of three or more independent groups.

Also: Non-parametric one-way ANOVA · Kruskal-Wallis test for k samples · Kruskal-Wallis rank analysis of variance · Kruskal-Wallis test

One-way Kruskal-Wallis test Nonparametric hypothesis testing used to compare the medians or general distributions of ranges between three or more independent groups of study subjects.

Also: non-parametric analysis of variance · Kruskal-Wallis rank test · non-parametric Kruskal-Wallis contrast

Levene's test for homogeneity of variances Hypothesis contrast that evaluates whether different study groups present equal variances in their statistical distributions based on absolute deviations.

Also: Levene test · Levene's test of equality of variances · Levene homoskedasticity · Levene's equality of variances test

Log-rank test Non-parametric hypothesis test used to compare the survival curves of two or more independent groups during the entire follow-up period.

Also: log-rank test · Mantel-Cox test · log-rank test · log-rank survival contrast

McNemar test Non-parametric hypothesis testing used to compare two paired or related proportions from a before-and-after study design with dichotomous nominal categorical variables.

Also: McNemar test · McNemar's exact test for related proportions · chi-square test for dichotomous paired data · McNemar's correlated proportions test

Kolmogorov-Smirnov normality test Non-parametric hypothesis testing to evaluate whether the observed distribution of a sample significantly adjusts to a theoretical normal reference distribution, ideal for samples of size greater than fifty.

Also: Kolmogorov-Smirnov test · K-S goodness-of-fit test · K-S test of normality · K-S normality contrast

Shapiro-Wilk normality test Non-parametric hypothesis testing designed to verify whether a set of quantitative observations comes from a normal distribution, optimally recommended for samples of size less than fifty.

Also: Shapiro-Wilk test · S-W normality test · Shapiro's normality significance test · S-W normality contrast

Wilcoxon signed rank test Non-parametric hypothesis testing for paired samples that evaluates whether the range of differences between two repeated measurements in the same subjects differs from that expected by chance.

Also: Wilcoxon signed rank test · Wilcoxon test for paired data · Wilcoxon test of two related samples · paired Wilcoxon contrast

Wilcoxon signed rank test Non-parametric test used to compare the difference in ranges of two repeated or paired observations of continuous or ordinal variables.

Also: Wilcoxon signed rank test · Wilcoxon test for related samples · Wilcoxon couple · Wilcoxon of repeated observations

Fisher's exact test Non-parametric statistical test that calculates the exact probability of the association between two categorical variables, especially recommended for small samples in two-by-two contingency tables.

Also: Fisher's exact test · Fisher's exact probability test · Fisher's exact method · Fisher's exact analysis

Student's t test for independent samples Parametric hypothesis testing used to compare the means of a continuous variable in two independent and mutually exclusive groups of subjects.

Also: two-sample Student's t test · independent samples t-test · bivariate Student's t-analysis · Student's t of group comparison

Student's t test for paired samples Parametric hypothesis testing used to compare the means of a continuous variable measured twice in the same group of subjects or in matched pairs.

Also: dependent samples t test · Student's t test for correlated data · intragroup Student's t · t test for pre-post measurements

Mann-Whitney U test Non-parametric test to evaluate differences in the ranges of a continuous or ordinal variable between two independent groups, non-parametric analogue of the Student t test.

Also: Wilcoxon-Mann-Whitney rank sum test · Mann-Whitney U test · non-parametric contrast of two independent samples · statistical U test

One-sided test Hypothesis test in which the rejection region of the null hypothesis is located at a single end of the probability distribution.

Also: one queue test · unilateral test · one-way hypothesis testing · one-tailed statistical test

Propensity score A statistical probability measure that calculates the estimated probability that a subject will receive a given treatment based solely on their profile of baseline confounding characteristics and covariates.

Also: propensity score · confusion balancing score · therapeutic allocation propensity index · covariate balancing score

High-dimensional propensity score Automated extension to conventional propensity scoring that evaluates and selects thousands of covariates from electronic medical records to massively reduce confounding bias.

Also: hdPS · high-dimensional propensity score · hdPS mass confusion balancing · HDPS automated propensity score

Score g Statistical measure that indicates the number of standard deviations that a sample observation is above or below the arithmetic mean of its own reference population.

Also: score z · z standardized value · average standardized deviation · standard z score

Quintile Any of the four values that segment a distribution of observations from lowest to highest into five subgroups with the same number of cases, twenty percent each.

Also: statistical quintile · twenty cutoff percentiles · division into quintiles · twenty percent cuts

Interquartile range Non-parametric statistical dispersion measure that represents the numerical difference between the third quartile and the first quartile of a data distribution.

Also: IQR · interquartile range · interquartile dispersion · interquartile range

Incremental cost-effectiveness ratio Mathematical quotient that represents the difference in costs between two treatment alternatives divided by the difference in their clinical effectiveness.

Also: RCEI · ICER · incremental cost-effectiveness coefficient · marginal cost-effectiveness ratio

Standardized mortality ratio Comparative quotient between the observed number of deaths in a study population and the number expected if that population had the mortality rates of a reference population.

Also: SMR · RME · standardized mortality rate · standardized mortality ratio

Hazard ratio Comparative expression that quantifies the relative rate at which events of interest occur between two independent survival groups at a given time of observation.

Also: hazard ratio · hazard ratio · Survival HR · hazard rate ratio · comparative instantaneous risk indicator

Incidence rate ratio Comparative quotient obtained by dividing the incidence rate of a disease in the group exposed to a risk factor by the incidence rate of the non-exposed group.

Also: IRR · incidence rate ratio · incidence density ratio · population hazard rate ratio

Absolute risk reduction Measure of therapeutic efficacy obtained through the arithmetic subtraction between the incidence of unfavorable events in the control group and that of the intervention group.

Also: RAR · absolute risk difference · absolute risk reduction · difference in therapeutic incidence rates

Relative risk reduction Proportion of the baseline risk of the control group that is reduced when applying the therapeutic intervention evaluated in the experimental group.

Also: RRR · relative risk reduction · relative effectiveness of treatment · proportion of therapeutic risk avoided

PROSPERO record International database that prospectively compiles protocol records from systematic health and social welfare reviews to prevent unnecessary scientific duplication.

Also: PROSPERO database · prospective record of revisions · PROSPERO protocol repository · international prospective registry of reviews

Stop rule Formal and pre-specified statistical criterion in the protocol of a clinical trial that determines the early termination of the study for reasons of safety, futility or overwhelming benefit.

Also: test stop rule · stopping rule · protocol stopping criterion · early termination rule

Ridge Regression Regularized regression method that introduces a quadratic penalty to the model coefficients to reduce variance and inflation in situations of extreme multicollinearity.

Also: ridge regression · ridge regularized regression · ridge coefficient estimation · regression with quadratic ridge penalty

Poisson regression Nonlinear multivariate statistical model designed to analyze count data or occurrences of discrete events that occur over time or specific physical space.

Also: log-linear Poisson model · regression for count data · Poisson analysis · Poisson rate regression

Elastic Net Regression Regularized regression model that balances the penalties of Lasso regression and ridge regression to address structural multicollinearity.

Also: elastic regression net · elastic net regression · combined regularization of coefficients · elastic net regularized regression

Lasso Regression Regularized regression technique that applies a linear absolute value penalty to the model coefficients, forcing some of them to be exactly zero to perform variable selection.

Also: minimum absolute selection and contraction · Lasso regularized regression · Lasso regression method · regression with linear Lasso penalty

Simple linear regression Mathematical model that estimates the linear relationship between a dependent quantitative variable and a single independent quantitative variable.

Also: linear regression of two variables · simple linear regression model · ordinary least squares regression · simple linear modeling

Simple logistic regression Statistical model used to estimate the probability of a binary or dichotomous outcome from a single continuous or categorical explanatory variable.

Also: simple logit model · binary logistic regression analysis · two-variable logistic regression · simple logistical adjustment

Mulnomial regression Logistic regression model that evaluates the effect of multiple covariates on a categorical dependent variable that has three or more inherently disordered nominal categories.

Also: polynomial logistic regression · multinomial regression analysis · multinomial logit model · modeling of nominal output variables

Ordinal regression Multivariate statistical regression model designed to evaluate the relationship between explanatory variables and a sequentially ordered ordinal categorical dependent variable.

Also: ordinal rank regression model · ordinal logistic regression analysis · ordinal multivariate regression · modeling of ordered dependent variables

Robust regression Regression analysis technique designed to provide stable coefficient estimates even in the presence of extreme outliers in the analyzed study sample.

Also: outlier-resistant regression · robust least squares estimation · robust statistical modeling · robust regression fit

Attributable risk Impact measure that estimates the difference between the incidence of a disease in the group exposed to a risk factor and the incidence in the non-exposed group.

Also: risk difference · attributable risk in exposed · absolute excess risk · absolute impact of exposure

Theoretical saturation Moment of qualitative research in which the collection of additional data does not provide new relevant information or alter the explanations of the clinical construct under study.

Also: data saturation · qualitative conceptual limit · theoretical analysis saturation · cessation of qualitative information collection

Sensitivity to change Intrinsic capacity of a scale or clinical health measurement instrument to detect subtle but real clinical variations in the patient's health status over time.

Also: responsiveness · scale reactivity · ability to detect clinical changes · scale time sensitivity

Berkson bias Selection bias that occurs in hospital case-control studies because hospitalization rates differ between exposed and unexposed people.

Also: Berkson paradox · hospital admission bias · Berkson selection bias · hospital selection bias

Citation bias Systematic error of scientific representativeness in which publications that report positive or significant effects are cited more frequently by third parties than those with non-significant results.

Also: citation bias · citation rate bias · biased over-citation of significant results · systematic academic citation error

Confounding bias by indication Distortion in the estimation of the therapeutic effect that occurs in observational studies because the patient's health status actively determines the clinician's choice of medical treatment.

Also: confounding by indication · confusion due to therapeutic indication · clinical prescription bias · systematic error in treatment selection

Residual confounding bias Uncontrolled confusion or remaining distortion of the effect estimate that persists after applying analytical techniques due to variables that were poorly measured or not recorded in the study.

Also: remaining confusion · unmeasured confounding bias · residual confusion control error · residual latent confounding bias

Wear bias Information bias that occurs due to the systematic loss of participants during the follow-up of a clinical study, altering the representativeness and results of the compared groups.

Also: attrition bias · attrition bias · tracking loss bias · selective loss of participants

Detection bias in EBM Systematic error in the evaluation of results due to the knowledge of the treatment by the clinical evaluators in charge of recording the study outcomes.

Also: detection bias · rater bias · observation bias of outcomes · systematic error of clinical detection

Illness duration bias Selection bias that occurs when screening tests preferentially detect cases with slow progression and a better prognosis over aggressive cases with rapid progression.

Also: length-time bias · progression speed bias · selective duration bias · slow detection systematic error

Publication bias Systematic tendency to publish studies with statistically significant or positive results more likely than those with negative or non-significant results.

Also: file bias · selective publication bias · publication bias · bias in reporting positive studies

Performance bias Systematic difference in the medical care received by the study groups apart from the therapeutic intervention that is formally under evaluation.

Also: performance bias · execution bias · concomitant care bias · systematic error of clinical performance

Recall bias Type of information bias common in retrospective studies where cases remember their past exposures differentially or in more detail compared to healthy controls.

Also: memory bias · recall bias · recall bias · systematic recall error

Selection bias Systematic error introduced when selecting or retaining study participants so that comparison groups differ in characteristics that influence the outcome.

Also: sampling bias · selective inclusion bias · systematic selection error · subject recruitment bias

Overdiagnosis bias Identification through screening tests of anomalies or diseases that would never have caused symptoms or death of the patient during their natural life expectancy.

Also: overdiagnosis due to screening · clinical overdetection · overdetection bias · detection of harmless subclinical disease

Diagnostic suspicion bias Information bias where the performance of diagnostic tests and the active search for the disease are biasedly intensified based on the patient's known prior exposure.

Also: diagnostic suspicion bias · selective diagnostic search bias · exposure-biased detection bias · diagnostic suspicion error

Lead time bias Distortion in the estimation of survival due to the early detection of a disease through screening, giving the false impression of greater survival without changing the real course of the disease.

Also: lead-time bias · early detection bias · misleading diagnostic advance · life extension illusion

Immortal Time Bias Observational selection bias that occurs when the study design erroneously assumes that an event-free follow-up period is part of the exposed comparison group.

Also: immortal time bias · temporal selective survival bias · time exposure mapping error · immortal time bias in tracking

Verification bias Systematic estimation error that occurs in diagnostic accuracy studies when the application of the reference standard depends on the result obtained in the evaluation index test.

Also: selective diagnostic confirmation · diagnostic referral bias · verification bias · diagnostic test verification bias

Disease spectrum bias Variation in the estimated values of sensitivity and specificity of a test that occurs because the study sample does not include the real clinical spectrum of the disease evaluated.

Also: spectrum bias · diagnostic population bias · severity bias of selected cases · diagnostic spectrum severity bias

Healthy worker bias Specific type of selection bias that occurs in occupational cohort studies because active workers systematically enjoy better health than the general reference population.

Also: healthy worker effect · occupational selection effect · health occupational survival bias · epidemiological bias of the healthy worker

Single blind Blinding procedure in which study participants do not know whether they have been assigned to the active intervention group or the control group.

Also: simple masking test · single blinding · single blind design · participant masking

Monte Carlo simulation Non-parametric computational technique that uses repeated random sampling of probability distributions to estimate uncertainty and variability in a decision-making model.

Also: Monte Carlo method · stochastic Monte Carlo simulation · probabilistic Monte Carlo analysis · uncertainty analysis by Monte Carlo

GRADE System Standardized methodological framework to systematically evaluate the quality of scientific evidence and grade the strength of clinical recommendations in medicine.

Also: GRADE classification · GRADE approach · GRADE methodology · GRADE grading of certainty

Overfixation Statistical modeling error in which a mathematical model fits so closely to the random data of the original training set that it loses all predictive power with new test data.

Also: overfitting · overfitting of regression models · data noise memorization · overparameterization of models

Area under the cumulative classification curve Numerical probability index derived from network meta-analysis that summarizes the overall probability that a specific treatment will be ranked in the best efficacy positions.

Also: SUCRA · SUCRA cumulative classification probability · SUCRA index of treatments · network cumulative classification surface

Progression-free survival Clinical outcome measure in oncology that indicates the time that elapses from the start of treatment until the documented worsening of the disease or the death of the patient from any cause.

Also: SLP · PFS · tumor progression-free interval · survival without disease progression

Sphericity assumption Theoretical condition required for repeated measures analysis of variance that assumes that the variances of the differences between all pairs of measurements are uniformly identical.

Also: sphericity of difference variances · Mauchly assumption of sphericity · homogeneity of repeated differences · statistical sphericity of variances

Proportional hazards assumption Fundamental theoretical condition of the Cox model that assumes that the hazard ratio between the study groups remains constant throughout the entire follow-up period.

Also: proportionality of risks · Cox assumption of proportionality · temporal constancy of hazard rates · Cox proportional hazards assumption

Effect size Standardized quantitative measure of the magnitude or strength of a difference or association observed in a study, regardless of the sample size selected.

Also: effect size · magnitude of clinical effect · effect strength indicator · standardized estimate of difference

Discount rate Financial factor applied in health economic evaluations to adjust and reduce the value of future health costs and benefits to the actual present value.

Also: economic update rate · discount of future costs · health discounting · temporary cost adjustment rate

Error rate per family Cumulative probability of making at least one type I error in a complete set of simultaneous multiple statistical comparisons carried out in the same study.

Also: FWER · family-wise error rate · false positive probability per test set · overall error rate due to multiplicity

False discovery rate Correction procedure for multiple comparisons designed to identify and control in a balanced way the expected proportion of false discoveries or type I errors in big data analysis.

Also: FDR · false discovery rate · controlled false discovery rate · false discovery rate control

Incidence rate Measurement of the speed of appearance of new cases of a disease in a population during a given period of time, expressed in relation to the size of said population.

Also: incidence density · incidence speed · disease development rate · speed of appearance of cases

Fatality rate Proportion of individuals in a defined population diagnosed with a specific disease who die from it within a given period of time.

Also: disease fatality rate · proportion of deaths per clinical case · case-specific mortality · clinical lethality indicator

Raw mortality rate Total number of deaths recorded in a given population during a period of time divided by the total number of people at risk in that same population.

Also: overall mortality rate · crude population mortality · general death rate · crude mortality rate

Objective response rate Cumulative proportion of cancer patients who experience a prespecified and confirmed reduction in tumor size after administration of a treatment under evaluation.

Also: ORR · objective tumor remission rate · cumulative objective clinical response · objective tumor response rate

Bayes' Theorem Probability theory formula that calculates the probability of a clinical event based on knowledge or previous conditions related to said event.

Also: Bayes' law · Bayes conditional probability principle · Bayesian update theorem · Bayes posterior probability calculation

Central limit theorem Fundamental principle that states that the sampling distribution of the mean approaches a normal distribution as the sample size increases, regardless of the shape of the original population distribution.

Also: law of large numbers for averages · probabilistic central limit theorem · principle of asymptotic normality · normal convergence of means

Grounded theory Systematic qualitative research methodology that deals with developing conceptual explanations and scientific theories from the systematic coding and analysis of qualitative observational data collected inductively.

Also: grounded theory · inductive data theory · qualitative analysis that generates concepts · grounded qualitative methodology

Triple blind Blinding procedure in which the participants, clinical researchers and the team in charge of statistical analysis of the data are unaware of the treatment assignment.

Also: triple masking · triple blinding · triple-blind design · total blind analysis

Cost-effectiveness threshold Maximum monetary limit that a health system is willing to pay for each additional unit of health obtained through a new medical intervention.

Also: cost threshold per QALY · maximum willingness to pay for health · incremental cost-effectiveness threshold · public health financing limit

Cramer's V Non-parametric association measure with a numerical range between zero and one used to quantify the strength of the association between two nominal variables with more than two classification categories.

Also: Cramer's V coefficient · Cramer's nominal association · Cramer's V statistic for contingency tables · Cramer's V association intensity

Cross validation Mathematical model validation technique that consists of dividing the sample into mutually exclusive subgroups to train the prediction algorithm and evaluate its predictive capacity with data not included in an iterative manner.

Also: cross-validation · k-fold cross validation · repeated sample division method · model validation by resampling

Concurrent validity Degree to which scores obtained by a new clinical instrument correlate strongly with the results of another standard measure administered simultaneously.

Also: criterion matching validity · simultaneous instrumental agreement · concurrent correlative validity · concurrent diagnostic accuracy

Construct validity Degree to which a test or measurement instrument consistently measures the theoretical dimension, abstract concept or psychological property for which it was developed.

Also: theoretical validity · construct confirmation · conceptual validity · exact measurement of abstract variables

Content validity Degree to which the items that make up a measurement instrument or questionnaire exhaustively and adequately represent the clinical construct that is intended to be evaluated.

Also: item sampling validity · thematic validity · exhaustiveness of content · representativeness of clinical items

Criteria validity Degree of statistical coincidence or correlation of a new clinical measurement instrument against an independently established and validated reference test or gold standard.

Also: validity with external reference · standard criterion comparison · correlative instrumental validity · external comparison validity

External validity Degree to which the findings of a clinical study can be generalized and reliably applied to populations, settings, or conditions other than those of the sample studied.

Also: generalizability · generalization validity · external applicability · external representativeness

Internal validity Degree to which the results of a study are methodologically correct and are free of bias or confounding variables, ensuring that the observed cause-effect relationship is real.

Also: methodological validity · internal rigor of the study · internal credibility · accuracy of the causal effect

Logical validity Intuitive and superficial degree to which a test or health measurement instrument appears to plausibly measure the clinical characteristic for which it was originally designed.

Also: face validity · face validity · logical content acceptability · validity of clinical appearance

Predictive validity Type of criterion validity of a clinical instrument that evaluates the degree of precision with which its current scores consistently predict clinical outcomes measured in the future.

Also: prospective criterion validity · consistent construct prediction · prospective validity · predictive accuracy of questionnaires

Qualitative variable Attribute or characteristic of the study subjects that cannot be measured numerically, but rather expresses a specific quality, category or property.

Also: categorical variable · discrete qualitative variable · attribute scale · non-numeric variable

Quantitative variable Variable that can be expressed numerically, allowing mathematical operations and the exact quantification of the magnitude or intensity of the evaluated attribute.

Also: numeric variable · quantitative scale · metric scale variable · parametric quantification

Dependent variable Result or response variable that is measured in a study to evaluate the effect of the manipulation or presence of the explanatory variables.

Also: result variable · response variable · criterion variable · outcome variable

Independent variable Exposure variable or study factor that is assumed to cause, predict or influence the variations observed in the dependent variable.

Also: explanatory variable · exposure variable · predictive covariate · explanatory factor

Variance Parametric dispersion measure that is equivalent to the average of the square of the deviations of the data with respect to their arithmetic mean.

Also: sample variance · squared standard deviation · quadratic dispersion · mean squared deviations

Violation of clinical protocol Serious methodological deviation from the standards of a clinical trial that directly affects the safety of the participants or substantially alters the validity of the results obtained.

Also: major protocol violation · violation of clinical trial guidelines · critical deviation from study protocol · major violation of experimental protocol

Controlled MeSH vocabulary Thesaurus of standardized medical terminology from the United States National Library of Medicine used for accurate indexing and searching of articles in MEDLINE.

Also: medical subject headings · MeSH descriptors · Medical Subject Headings · MeSH structured medical terminology

Statistics and MBE

Other glossary specialties