A term applied, originally by Joachim Wohlwill (1928-1987), to the form or mode of the relationship between the chronological age of an individual and the changes occurring in that person on some specified dimension of behavior. By ‘form or mode’ is meant either qualitative change (e.g., in terms of a sequence of stages) or quantitative change (e.g., in terms of an exponential function). Sometimes referred to as a developmental trajectory.
See Behavior variable, Developmental acceleration, Developmental trajectories, Exponential, Linear growth model, Logistic growth model, Quantitative and qualitative change, Trend