Convergent and Discriminant Validity of the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP) and the Vineland Adaptive Behavior Scales (VABS).

Behavior analysts frequently use the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP) to assess the language and social skills of children with autism in everyday practice and in research. Despite the widespread use of the VB-MAPP, its psychometric characteristics have not been extensively investigated. To provide information about its convergent validity, we calculated correlations between scores earned by 235 children with autism on the VB-MAPP and the Vineland Adaptive Behavior Scale (VABS), a commonly used assessment with good reliability and validity. We obtained moderate or strong positive correlations between the VB-MAPP Milestones score and VABS Communication, Socialization, and Daily Living Skills subdomains. There was also a strong positive correlation between the VB-MAPP Milestones score and VABS overall raw score. These findings suggest that the VB-MAPP Milestones Assessment measures aspects of social and communicative behavior comparable to those indexed by these VABS subdomains which, like prior findings, supports the use of the Milestones Assessment. No significant relationship was observed between the VB-MAPP Barriers score and the VABS Internalizing, Externalizing, or overall Maladaptive Behavior scores. These findings, like prior findings, question the value of the VB-MAPP's Barriers Assessment as a measure of maladaptive behavior.

Inter-Rater Agreement for the Milestones and Barriers Assessments of the Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP).

We determined inter-rater agreement for the VB-MAPP, an instrument sometimes used in planning educational goals and evaluating intervention effects for young people with autism. A pair of raters independently rated each of 32 children diagnosed with autism. Intraclass correlation coefficients for the total Milestones and Barrier scores were 0.876 and 0.629, respectively, indicating good and moderate reliability. There was variability in reliability in the different domains of the Milestones Assessment, with most indicating moderate reliability, and most of the individual Barriers Assessment domains indicating poor reliability. These are the first data relevant to the reliability of the VB-MAPP, they suggest that further evaluation of its reliability is merited and that a high reliability for individual domains should not be assumed.