To date, the COGA study has amassed brain function data on over 9871 participants, including 7837 with data at more than one time point (Table 1). Please see 2. Sample and Clinical Data for an overview of the different data collection waves, the research question guiding the focus of the data collection, the numbers of participants assessed at each, and tabular summaries of their characteristics. Briefly, data collection has focused on different participant subsets over time, depending on the research emphasis. Table 1 presents a comparison of key characteristics across the different “waves” of data collection. For several different subsets of participants and data collections, there are multiple assessments available on the same individuals. However, only the “Prospective study” which focused on assessments of youth aged 12–22 at two‐year intervals was specifically designed as a longitudinal study. 85% of this subsample has at least three follow‐up assessments, and a “non‐response analysis” indicated that individuals who did not return for follow‐ups were younger, but no significant differences regarding other key characteristics have been observed. We continue to take measures to ensure
