Participants and drop-outs in a longitudinal study.
D000223:Adaptation, Psychological; D000368:Aged; D001290:Attitude; D003863:Depression; D004467:Economics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D012106:Research; D012179:Retirement; D012924:Social Conditions; D013223:Statistics as Topic