ABSTRACT
Empirical researchers often inquire about systematic interindividual differences in change (i.e., whether individual change over time differs from person to person in systematic and interesting ways). Typically, such questions are concerned with the relationship between change in a single continuous outcome—mathematics achievement, say—and selected exogenous time-invariant predictors of that change, such as measures of a student’s background, environment, and treatment. Examples include the following: Does the rate at which students learn mathematics differ by attributes of the academic programs in which they are enrolled? Are longitudinal changes in mathematics related to the student’s health status, gender, and home background?
