Medical uncertainties -- Basics of medical studies -- Sampling methods -- Designs for observational studies -- Medical experiments -- Clinical trials -- Numerical methods for representing variation -- Presentation of variation by figures -- Some quantitative aspects of medicine -- Clinimetrics and evidence-based medicine -- Measurement of community health -- Confidence intervals, principles of tests of significance, and sample size -- Inference from proportions -- Relative risk and odds ratio -- Inference from means -- Relationships: quantitative data -- Relationships: qualitative dependent -- Survival analysis -- Simultaneous consideration of several variables -- Quality considerations -- Statistical fallacies.