It's the destination and it's the journey: using multilevel modeling to assess patterns of change in psychotherapy.
BACKGROUND
The pairing of analysis of variance (ANOVA)-based analyses with designs lacking multiple measurement of client change may lead to conclusions that are inconsistent with theoretical expectations about how change will occur. Multilevel modeling (MLM), when used with multiple assessments of client outcomes, provides a flexible set of tools to analyze trajectories of client change.


OBJECTIVE
The authors present an overview of MLM and growth curve analysis as applied to psychotherapy outcome. Results from a simulated data set illustrate how MLM-specifically, growth curve analysis-can be used to test hypotheses from randomized clinical trials.


RESULTS
Growth curve analyses were applied to simulated data from an experimental design (treatment versus control group) with multiple assessments of client distress and a client individual difference variable. Results of growth curve analyses confirmed what was found with a pretreatment/posttreatment repeated-measures ANOVA but provided additional information not available from the ANOVA framework.


CONCLUSIONS
Given its flexibility, MLM is the recommended method to assess patterns of change in studies of psychotherapy outcome.
Department of Psychology, Illinois State University, Normal, Illinois 61790-4620, USA. jhkahn@ilstu.edu
Jeffrey H
JH
Kahn
W Joel
WJ
Schneider
D000704:Analysis of Variance; D006801:Humans; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011613:Psychotherapy