Among the 1 472 762 persons included in the study base, a total of 30 000 persons were chosen uniformly at random (Table 1) corresponding to 2.04% of the study base (=30 000/1 472 762). As the cohort members were chosen randomly, some cohort members may also have the disorders of interest.13, 14 Thus, the cohort selected is representative of the entire Danish population born in the same period.26 In addition, the cohort members are at risk of developing the disorder of interest during follow-up, whereas controls are typically conditioned to be healthy until the study ends.29 We have thereby identified the individuals to be included in the iPSYCH2012 sample. Next, we describe the enrichment with genetic and other biomarker data.
