Intelligence, verbal abilities, attitudes, interests, and social conditions of 380 Ss above 55 yr. of age were measured. Five yr. later Ss were retested. Some refused to cooperate again, and others had died or become ill. Retested Ss differed significantly from the total group, but in particular from the other subgroups. The prediction of death on the basis of sociopsychological variables was more successful for Ss below than above 65 yr. of age. It was concluded that developmental trends are based on increasingly biased samples, that previous studies have underestimated the amount of attrition, and that nonsurvivors under 65 yr. form a sociopsychological subgroup of different characteristics than survivors.
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