Cohort Studies

This chapter provides readers with the critical concepts to consider in designing and analyzing cohort studies. A cohort study is a powerful tool and suitable choice for conducting research for rare exposures in human populations. It can be used to assess associations between multiple exposures and multiple outcomes and identifying the risk factors and causes of diseases. The learning objectives of this chapter are as follows: (1) introduce a cohort study and its uses; (2) describe the design of a cohort study; (3) explain and differentiate the different types of cohort studies including retrospective, prospective, and ambi-directional designs; (4) discuss the selection of study populations, with sources of information on exposure, outcomes, and other key variables; (5) describe approaches to data analysis, including the calculation of person-time, with examples; (6) provide various examples of cohort studies; (7) explain advantages and disadvantages of cohort studies; and (8) discuss potential biases in cohort studies.