The NIMH-CPES sample was based on a multistage clus- tered area probability sample of the US population. The sample consisted of 20,013 American citizens. The mean age of the sample was 43.38. The sample was representative of the US population and also racially and ethnically diverse. Therefore, the results of these findings include different racial and ethnic backgrounds which most previous research has failed to consider. Further information on the sample designs can be found in Heeringa et al. (2004). Please refer to Table 1 for the main features of the sample designs of the Collaborative Psychiatric Epidemiology Studies.