Abstract

Observational studies are those studies where no intervention is carried out by the investigator. The researcher observes what happens to people under exposure conditions that have been determined by influences outside the control of the researcher. The main objective of observational studies is to determine prevalence, incidence, cause, prognosis or effect of treatment. The major problem in inferring causation in an observational study is that the exposed and unexposed groups may differ on other factors called confounders, that may themselves be causes of the outcome. The main analytical designs used in observational research are the cohort, cross-sectional and case-control studies. Observational studies are generally a cost-effective way of producing and investigating hypotheses before larger and more expensive study designs are carried out. Additionally, they are often the only realistic choice of research methodology. The STROBE statement provides guidance on how to report observational research well.