The importance of valid and reliable couple assessment has been increasing with growth in research on couple and family relationships as well as in therapeutic and educational interventions for couples and families. However, self-report instruments–the most popular type of couple assessment–have been criticized at least partly due to limitations in Classical Test Theory (CTT) which has been used solely in developing and evaluating couple assessments for decades. In an effort to address the limitations in the sole use of CTT in developing self-report couple assessments, the present study integrated a modern test theory called Item Response Theory (IRT) and evaluated the properties of subscales in the RELATionship Evaluation (RELATE) using the existing data from 4,784 participants. Using the Rasch rating scale or partial credit model which is one of the IRT models, the author demonstrated that some of the RELATE subscales had items and response categories that functioned less optimally or in an unexpected way. The results suggested that some items misfit the model or overlapped with other items, many scales did not cover the entire range of the measured construct, and response categories for many items malfunctioned. The author made recommendations on possible remedies that could be adopted to improve the function of individual scales and items.



College and Department

Family, Home, and Social Sciences; Family Life; Marriage, Family, and Human Development



Date Submitted


Document Type





Rasch model, Item Response Theory, RELATE, scale evaluation