The approach and evolution of epidemiology -- Measures of disease frequency -- Comparing disease frequencies -- Sources of public health data -- Descriptive epidemiology -- Overview of epidemiologic study designs -- Experimental studies -- Cohort studies -- Case-control studies -- Bias -- Confounding -- Random error -- Effect measure modification -- Critical review of epidemiologic studies -- The epidemiologic approach to causation -- Screening in public health practice -- Ethics in research involving human participants -- Answers to chapter questions.