Validation of the Moral Reasoning Questionnaire against Rasch Measurement Theory

To support teachers in facilitating students’ moral reasoning development as specified within the Singapore Ministry of Education Character and Citizenship Education curriculum, the Moral Reasoning Questionnaire (MRQ) was developed and underwent preliminary validation. Based upon expert reviews, cognitive interviews and a classical test theory-based factor analytic approach, the development and preliminary validation found evidence (i.e., content appropriateness, response processes and internal structure) to support the validity and reliability of the MRQ. This study aims to extend the validation by examining the purported MRQ items and scale at a deeper level on the Rasch Measurement Theory, given that it is the only model that presents appropriate properties of interval measurement on a log-linear scale. The Rasch analysis found anomalies including differential item functioning and disordered thresholds in the initial set of items. Upon remediation and a second Rasch analysis, the MRQ responses were consistent with that expressed by the Rasch model (i.e., an item with an endorsability higher than what a respondent would tend to endorse would have a lower probability of being endorsed than an item exhibiting an endorsability below what that respondent would tend to endorse) and hence, there was sufficient evidence to support measurement invariance, and that MRQ scores could be concluded to characterise persons invariantly across a continuum.