Cross‐sectional studies serve many purposes, and the cross‐sectional design is the most
relevant design when assessing the prevalence of disease, attitudes and knowledge among …

Confounding is an important source of bias, but it is often misunderstood. We consider how
confounding occurs and how to address confounding using examples. Study results are …

Longitudinal cohort studies can provide important evidence about preventable causes of
disease, but the success relies heavily on the commitment of their participants, both at …

Abstract Information bias occurs when any information used in a study is either measured or
recorded inaccurately. This paper describes some of the most common types of information …

Prospective and retrospective cohorts and case-control studies are some of the most
important study designs in epidemiology because, under certain assumptions, they can …

In this paper we present basic principles of planning and carrying out cross-sectional studies
in health sciences as well as analyzing the data collected in these studies. We present …

When investigators describe the study design they employed, the term retrospective cohort
commonly is selected and commonly used incorrectly. In a prospective cohort, investigators …

Many clinicians report that they cannot read the medical literature critically. To address this
difficulty, we provide a primer of clinical research for clinicians and researchers alike …

Systematic reviews of observational studies of aetiology are especially important. Studies of
this type tend to be limited in size and thus by examining multiple similar studies …

Abstract Mackenzie, SG, and A. Lfppman (Dept of Epidemiology and Biostatistics, McGill U.,
Montreal, Quebec H3A 1A2, Canada). An investigation of report bias in a case-control study …