Cohort Studies

Cohort studies compare a particular outcome (i.e., lung cancer or diabetes) in groups of individuals who are alike in many ways (i.e., age, gender) but differ by a certain characteristic, and follow them over time. For example, female nurses who smoke compared with female nurses who do not smoke to assess lung cancer risk. Cohort studies can be prospective (participants are followed forward in time) or retrospective (researchers look at participants' past medical and lifestyle history).