Behavioral development and construct validity: The principle of aggregation.

Hypothesized that many null findings in behavioral development (presumed to be unrelated because of repeated failures to obtain substantial correlations) have often been due to failures to aggregate. The principle of aggregation states that the sum of a set of multiple measurements is a more stable and representative estimator than any single measurement. This greater representation occurs because there is inevitably some error associated with measurement. By combining numerous exemplars, such errors of measurement are averaged out, leaving a clearer view of underlying relationships. The usefulness of this principle is illustrated in 12 major areas of developmental research in which the issue of negligible correlations figures prominently: (a) the validity of judges' ratings, (b) the cross-situational consistency of moral character and personality, (c) the longitudinal stability of personality, (d) the coherence of stages of cognitive development, (e) metacognition, (f) the attitude–behavior relationship, (g) the personality–behavior relationship, (h) the role-taking/altruism relationship, (i) the moral-judgment/altruism relationship, (j) the legitimacy of the construct of attachment, (k) the existence of sex differences, and (l) the assessment of emotionality in animals. (109 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)