Continuity and Stability in Development.

Developmental science is centrally concerned with both consistency and change in characteristics through time. Consistency and change in development are tracked by group mean level continuity and individual order stability. Group mean level and individual order consistency and change are both developmentally informative and can co-exist conceptually and empirically as the two are partially orthogonal perspectives on development. Continuity and stability are broadly applicable to characteristics of the individual, dyad, and environment. Significantly, absent the distinctions we draw between mean level continuity and individual order stability, researchers who use the terms willy-nilly leave their readers in the dark as to which key feature of development is meant. In this article, we distinguish the two types of consistency and change, their measurement, importance, moderation, and implications.