Illustrating the Applicability of IRT to Implementation Science: Examining an Instrument of Therapist Attitudes.

Pragmatic instruments with psychometric support are important to advance dissemination and implementation (D&I) research, but few well-researched D&I instruments exist. Item response theory (IRT), an approach that is underutilized in D&I, can help with the development of actionable and brief instruments. This paper provides an overview of IRT for D&I researchers and examines an instrument of therapist attitudes using IRT measurement models. Eight items of the Attitudes Towards Individualized Assessment-Monitoring and Feedback (AIA-MF) Clinical Utility scale were fit to the Graded Response Model in a national sample of master's level therapists. Various IRT model characteristics including item threshold and discrimination parameters, information, and item and person fit were examined. Discrimination and thresholds parameters showed significant variability across the eight items. Item information curves also showed that each item contributed variably to the total test information, suggesting that items 4 and 5 reliably measure therapist attitudes across the latent continuum and items 3 and 6 warrant further investigation. Results suggest that IRT models can help D&I researchers examine existing instruments with greater specificity than traditional measurement methods, thus increasing measurement precision while lowering response burden, both important considerations for the field.