Aurelie Lange

68 | Chapter 4 Abstract The Therapist Adherence Measure (TAM-R) is a central assessment within the quality- assurance system of Multisystemic Therapy (MST). MST is an intensive, home- and community-based treatment for adolescents (12-18 years old) showing externalizing behavioral problems or delinquency. Although the validity and reliability of the TAM have been examined in several US studies, these studies found varying numbers of latent factors underlying the scores on the TAM. Therefore, the current study aimed to re-examine its factor structure in the Netherlands. For this purpose, we used two independent samples of families participating in MST in the Netherlands. The factor structure was explored using a Principal Component Analysis (PCA) in Sample 1 (N=580). As the TAM-R was completed multiple times by most families, we could replicate our PCA-analyses across two random subsamples of questionnaires from Sample 1, each consisting of 1 TAM-R assessment per family. A two-component solution showed to be the most appropriate. The two components were labeled therapist adherence and client-therapist alliance, respectively. Cross-loading items were dropped to create two well-differentiating components. Internal consistency of the reduced components was good. This two-factor model also showed good model fit in a subsequent Confirmatory Factor Analysis (CFA) in Sample 2 (N=723). The current finding of an alliance-component corroborates previous studies and fits with the focus of the MST-treatment model on creating engagement. Although only a subset of the items was retained for the final component-solution, MST clinicians are advised to continue to rely on the full TAM-R for feedback and quality assurance.