[Recovery measure Individual Recovery Outcomes Counter (I.ROC): scoring on common metrics].

Background: In this article we provide norm scores for the I.ROC, an instrument for measuring recovery. Normative data from the general population are presented in the form of two common metrics: percentile rank (PR-)scores and T-scores. The pros and cons of both metrics are discussed and their relationship is considered.

Method: The literature on the psychometric characteristics of the I.ROC is summarized. Data from a large sample from the Dutch general population were used to calculate T- and PR-scores. Two approaches for converting raw scores into T-scores were compared: a simple linear conversion and a conversion based on the curvilinear relationship of raw scores with normalized (rankit) T-scores.

Results: The frequency distribution of raw scores on the I.ROC was approximately normal and a linear formula was sufficient for most raw scores. Only for very low scores did we find substantial differences between linear and normalized T-scores. A crosswalk table and figure are provided to convert raw scores to T-scores and PR-scores.

Conclusion: The I.ROC appears to be an instrument well aligned with a comprehensive recovery paradigm. Employment of common metrics (T-scores and PR-scores) is recommended for a clear presentation of results to both the client and professional. For occasional conversion of raw scores to T-scores, a straightforward linear formula suffices; for scoring software, a more precise and sophisticated curvilinear formula for normalized T-scores is advised.