Led by ADHD expert Joseph Biederman, a team of Harvard University researchers tested the stability of CBCL scores obtained over a 4-year interval for boys diagnosed as having ADHD. The boys were initially seen either in a pediatric psychopharmacology program at Massachusetts General Hospital or in the pediatric service of a Health Maintenance Organization.
They unequivocally met DSM-III-R criteria for ADHD and participated in a thorough longitudinal study that yielded findings reported in numerous publications. The Harvard team performed many analyses of relations between the boys’ initial CBCL scores and their scores 4 years later, including intraclass correlations (ICCs), Pearson correlations, kappa coefficients, odds ratios, and comparisons of profiles of mean scores.
Based on high levels of consistency between CBCL scores, the researchers “found good evidence for the stability of both the clinical and competence scales of the CBCL as well as for its composite Internalizing, Externalizing, and Total Problems scales over a 4-year period. In addition to group stability, the robust findings obtained from ICCs and kappa coefficients document substantial stability over time within individuals.
These results support the informativeness of the CBCL as a useful measure of longitudinal course in clinical samples of youth with ADHD” (p. 501). Biederman et al. also cited findings from studies of community samples showing highly stable CBCL scores.
Reference: Biederman, J., Monuteaux, M.C., Greene, R.W., Braaten, E., Doyle, A.E., & Faraone, S.V. (2001). Long-term stability of the Child Behavior Checklist in a clinical sample of youth with Attention Deficit Hyperactivity Disorder. Journal of Clinical Child Psychology, 30, 492-502.