We also considered the challenge of obtaining samples that are adequate in size and representativeness. As in all studies, the ideal cohorts would be large, diverse, and population-representative. Moving away from the convenience samples that have characterized studies in the field, such cohorts would allow for adequate powering of analyses and avoid problems of clustering and interclass correlation. Large, diverse, representative samples minimize problems of type I and type II error that have dogged molecular epidemiologic studies,[39] and improve the generalizability of study findings. Moreover, as the extant research has been relegated to small, selected samples, reproducing studies in different contexts and among different populations groups is needed to further generalize our understanding of the role of epigenetic modifications in the etiology of psychopathology.
