Applying Rasch methodology to examine and enhance precision of the baby care questionnaire

The Baby Care Questionnaire (BCQ) is an established ordinal measure of parenting beliefs about infant care, which includes structure and attunement scales. Rasch analysis is a powerful method to examine and improve psychometric properties of ordinal scales. This study aimed to evaluate the psychometric properties and improve precision of the structure and attunement scales of the BCQ using Rasch methodology. A Partial Credit Rasch model was applied to a sample of 450 mothers from the United Kingdom (n = 225) and New Zealand (n = 225) who completed the BCQ. Initial analyses indicated acceptable reliability of the structure and attunement scales of the BCQ, but some items showed misfit to the Rasch model associated with local dependency issues in both scales. After combining locally dependent items into testlets, both scales of the BCQ met expectations of the unidimensional Rasch model and demonstrated adequate and strong reliability and invariance across countries and person factors such as participants’ age and their baby’s sex. This permitted the generation of conversion algorithms to transform ordinal scores into interval data to enhance the precision of both scales of the BCQ. In conclusion, using Rasch methodology, this study demonstrated robust psychometric properties of the structure and attunement scales of the BCQ after minor modifications. The ordinal-to-interval conversion tables published here can be used to further enhance the precision of the structure and attunement scales of the BCQ without changing their original response format. These findings contribute to the enhancement of precision in measuring parenting beliefs about infant care