Classification, direction, and prevention of bias in epidemiologic research

J Occup Med. 1992 Mar;34(3):265-71. doi: 10.1097/00043764-199203000-00010.


We describe an extension of an existing framework used by several investigators for classifying various types of bias. The framework consists of three categories of bias: selection, information, and confounding. The existing framework is expanded to include subclassification according to the type of study design: cross-sectional, case-control, retrospective cohort, and prospective cohort. Direction and method of prevention of biases within each category in the framework are discussed. This article provides a useful checklist for epidemiologists to determine possible sources and methods of reduction of bias that are specific to a particular type of study design.

MeSH terms

  • Bias*
  • Epidemiology*
  • Humans
  • Observer Variation
  • Preventive Medicine
  • Research Design*
  • Selection Bias