Rasch analysis and differential item functioning of the marital happiness scale in Oman

Marital happiness is an important variable in family life in Oman as a coherent Muslim society. Recent societal attention to marital happiness and divorce rates in Oman underpins the need for a valid and reliable instrument to precisely measure the levels of marital happiness among Omani spouses. However, a close look at the measurement of marital happiness reveals the scarcity of reliable and valid instruments developed using item response theory assumption. To this end, we used data from a nationally representative sample of Omani couples to develop and validate the marital happiness scale in light of the Rasch rating scale model. Using Winsteps software version 3.80.1 ( https://www.winsteps.com/index.htm ), we examined unidimensionality, rating scale functioning, item infit and outfit statistics, item polarity, reliability and separation indices of items and persons, the item hierarchy, and DIF across genders. The findings indicated that marital happiness is a single unidimensional construct and that the scale has adequate psychometric properties in Oman despite the existence of DIF in certain items. Limitations and further research topics concerning cross-cultural validation of the scale and qualitative refinement of the items showing DIF were discussed.