How to plot growth curves based on SPSS output? Illustrations based on a study on adolescent development

摘要

Individual growth curve (IGC) analyses are often used to examine growth curves of participants under different conditions, such as differences in the growth trajectories in an experimental group and a control group. Although researchers can use Linear Mixed Models (LMM) in SPSS to conduct IGC analyses, growth curves are not automatically generated from SPSS output, and researchers have to plot growth curves based on the information derived from the SPSS output. To facilitate the plotting of individual growth curves to aid the interpretation of LMM results, an EXCEL program was written by the researchers. Examples and step-by-step illustrations are presented in the paper regarding how to use this EXCEL program to plot growth curves based on the SPSS output.