Observational Study

Abstract

Observational studies include cohort studies, cross-sectional studies, case-control studies, case series studies and descriptive studies. Each study design has good and bad points. If bias in an observational study is not recognized, misunderstanding about the contents of the study may occur. Factors that produce misunderstanding include random error, systemic error, confounding of cause-result relation and adjustments of them. To understand these factors and adjustments will prevent misunderstanding of observational studies.