Scientific Concept of the National Cohort (status ... - Nationale Kohorte

A.6
A.6 Planned statistical analyses and statistical power considerations
figures 6.2 and 6.3 (and supplementary Tables S6.2 and S6.3) indicate that studies which
include at least 300–500 cases of a specific disease, with control-to-case ratios varying between
2:1 and 4:1, will have a statistical power of 0.80 (at a significance level of 0.05) to
detect an odds ratio of about 1.4–1.6 for a binary exposure with 20% population prevalence,
or an odds ratio of about 1.5–1.7 for top vs. bottom quartile categories of an exposure or
risk factor in the controls. For exposures or risk factors measured on a continuous scale,
and which are approximately normally distributed, we will be able to detect a standardized
exposure difference (A) of about 0.14–0.20, again at a significance level of 0.05 (figure 6.4,
supplementary Table S6.5) with a study of this size. The number of 300–500 incident cases
of disease corresponds, for example, to the rarer forms of cancer listed in Table 6.3 or to incident
cases of type 2 diabetes among adults