Validation of the one pass measure for motivational interviewing competence

•We test a new coding tool for practitioner competence in motivational interviewing (MI).•We use a sample of 27 student counselors and evaluate them using both tools.•The new tool (OnePass) shows high levels of inter-rater reliability.•There is moderate concurrent validity with the Motivational Interviewing Treatment Integrity (MITI) tool.•There is promise for OnePass as a lower cost, reliable way of evaluating MI practitioners.

ObjectiveThis paper examines the psychometric properties of the OnePass coding system: a new, user-friendly tool for evaluating practitioner competence in motivational interviewing (MI). We provide data on reliability and validity with the current gold-standard: Motivational Interviewing Treatment Integrity tool (MITI).MethodsWe compared scores from 27 videotaped MI sessions performed by student counselors trained in MI and simulated patients using both OnePass and MITI, with three different raters for each tool. Reliability was estimated using intra-class coefficients (ICCs), and validity was assessed using Pearson's r.ResultsOnePass had high levels of inter-rater reliability with 19/23 items found from substantial to almost perfect agreement. Taking the pair of scores with the highest inter-rater reliability on the MITI, the concurrent validity between the two measures ranged from moderate to high. Validity was highest for evocation, autonomy, direction and empathy.ConclusionOnePass appears to have good inter-rater reliability while capturing similar dimensions of MI as the MITI. Despite the moderate concurrent validity with the MITI, the OnePass shows promise in evaluating both traditional and novel interpretations of MI.Practice implicationsOnePass may be a useful tool for developing and improving practitioner competence in MI where access to MITI coders is limited.