Nonlinear Growth Curves in Developmental Research

TLDR

Developmentalists use growth models to study change processes, and nonlinear growth curves enable estimation of initial levels, growth spurts, and asymptotic levels. The paper progresses from linear to increasingly complex nonlinear growth models, discusses their added insights, and fits a collection of these models to repeated height measures from the Berkeley Growth and Guidance Studies spanning early childhood to adulthood.

Abstract

Developmentalists are often interested in understanding change processes, and growth models are the most common analytic tool for examining such processes. Nonlinear growth curves are especially valuable to developmentalists because the defining characteristics of the growth process such as initial levels, rates of change during growth spurts, and asymptotic levels can be estimated. A variety of growth models are described beginning with the linear growth model and moving to nonlinear models of varying complexity. A detailed discussion of nonlinear models is provided, highlighting the added insights into complex developmental processes associated with their use. A collection of growth models are fit to repeated measures of height from participants of the Berkeley Growth and Guidance Studies from early childhood through adulthood.