Review of Study Design Concepts

Summary

Consolidates the four standard observational designs, mapping cross-sectional, cohort, case-control, and ecological studies to the prevalence ratios, risk ratios, incidence rate ratios, and odds ratios each one produces. Uses the sedentary-and-diabetes example to expose the cross-sectional inability to establish temporal sequence, then develops cohort and case-control designs along with the prevalence-incidence bias known as Neyman or survival bias. Closes with ecological designs and the ecological fallacy, then introduces evidence synthesis through systematic reviews and meta-analysis as the bridge to controlled studies.