Glossary of common biostatistical and epidemiological terms
- Author
- Peter A L Bonis, MD
Peter A L Bonis, MD
- Chief Medical Officer — UpToDate
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- Tufts University School of Medicine
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- Joann G Elmore, MD, MPH
Joann G Elmore, MD, MPH
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- Section Editor — General Medicine
- Professor of Medicine, Adjunct Professor of Epidemiology
- University of Washington School of Medicine
- David M Rind, MD
David M Rind, MD
- Section Editor — General Medicine
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- Harvard Medical School
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Carrie Armsby, MD, MPH
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INTRODUCTION
This topic review will provide a catalog of common biostatistical and epidemiological terms encountered in the medical literature.
STATISTICS THAT DESCRIBE HOW DATA ARE DISTRIBUTED
Measures of central tendency — Three measures of central tendency are most frequently used to describe data:
●Mean equals the sum of observations divided by the number of observations.
●Median equals the observation in the middle when all observations are ordered from smallest to largest; when there are an even number of observations the median is defined as the mean of the middle two data points.
●Mode equals the observation that occurs most frequently.
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- Lubsen J, Hoes A, Grobbee D. Implications of trial results: the potentially misleading notions of number needed to treat and average duration of life gained. Lancet 2000; 356:1757.
- de Craen AJ, Vickers AJ, Tijssen JG, Kleijnen J. Number-needed-to-treat and placebo-controlled trials. Lancet 1998; 351:310.
- Weissler AM. A perspective on standardizing the predictive power of noninvasive cardiovascular tests by likelihood ratio computation: 1. Mathematical principles. Mayo Clin Proc 1999; 74:1061.
- Leening MJ, Vedder MM, Witteman JC, et al. Net reclassification improvement: computation, interpretation, and controversies: a literature review and clinician's guide. Ann Intern Med 2014; 160:122.
- Pencina MJ, D'Agostino RB Sr, Demler OV. Novel metrics for evaluating improvement in discrimination: net reclassification and integrated discrimination improvement for normal variables and nested models. Stat Med 2012; 31:101.
- Porta N, Bonet C, Cobo E. Discordance between reported intention-to-treat and per protocol analyses. J Clin Epidemiol 2007; 60:663.
- Gravel J, Opatrny L, Shapiro S. The intention-to-treat approach in randomized controlled trials: are authors saying what they do and doing what they say? Clin Trials 2007; 4:350.
TopTopic Outline
- INTRODUCTION
- STATISTICS THAT DESCRIBE HOW DATA ARE DISTRIBUTED
- Measures of central tendency
- Measures of dispersion
- TERMS USED TO DESCRIBE THE FREQUENCY OF AN EVENT
- Incidence
- Prevalence
- Person-years
- TERMS USED TO DESCRIBE THE MAGNITUDE OF AN EFFECT
- Relative risk
- Odds ratio
- Absolute risk
- Number needed to treat
- TERMS USED TO DESCRIBE THE QUALITY OF MEASUREMENTS
- Reliability
- Validity
- MEASURES OF DIAGNOSTIC TEST PERFORMANCE
- Sensitivity
- Specificity
- Predictive values
- Likelihood ratio
- Accuracy
- Net reclassification improvement and integrated discrimination improvement
- EXPRESSIONS USED WHEN MAKING INFERENCES ABOUT DATA
- Confidence interval
- Credible interval
- Errors
- Power
- TERMS USED IN MULTIVARIATE ANALYSIS
- TIME-TO-EVENT ANALYSIS (SURVIVAL ANALYSIS)
- Kaplan-Meier analysis
- Cox proportional hazards analysis
- STUDY DESIGNS
- Cohort study
- Case-control study
- Randomized controlled trial
- - Intention to treat
- Mendelian randomization
- REFERENCES