9 1 Advanced Cohort Study Design STAT 507
Table Of Content Prospective Cohort Design Cohort Study: Definition, Designs & Examples The British Doctors Study Missing data If you must physically locate and recruit the controls, set up clinic appointments, run diagnostic tests, and enter data, the effort of pursuing a large number of controls quickly offsets any gain. The bottom line is there is little additional power beyond a four-to-one ratio. Power increases but at a decreasing rate as the ratio of controls/cases increases. Little additional power is gained at ratios higher than four controls/cases. There is little benefit to enrolling a greater ratio of controls to cases. Prospective Cohort Design The simplest cohort design is prospective, i.e., following a group forward in time, but a cohort study can also be 'retrospective'. In general, the descriptor, 'prospective' or 'retrospective', indicates when the cohort is identified relative to the initiation of the study. In a cohort study, the ...