On two-wave measurement of individual change and initial value dependence.

This article focuses on two-wave change measurement and initial value dependence. Initially, some general methodological limitations associated with individual change measurement in a two assessment context are discussed. The method of "intra-individual and group-differential measurement of change" (Rueckert, 1989) is next evaluated. Use of a structural equation modeling approach is advocated in two-wave designs where the intention is to estimate the degree of interrelationship between growth or decline in a repeatedly assessed psychological construct and other variables. This approach is applied with the recently developed program RAMONA to the study of practice effects in a cognitive intervention study of plasticity in fluid intelligence of aged adults (Baltes, Dittmann-Kohli, & Kliegl, 1986).