Rasch model of the Bridging Social Capital Questionnaire

Abstract Bridging social capital is defined as the connections between individuals who are dissimilar with respect to socioeconomic status and other characteristics. We previously identified an important gap in the literature related to its measurement. We developed and validated a scale to measure bridging social capital to be used in Latinx immigrant populations living in the U.S using Classical Test Theory. The structure of the questionnaire comprised the following sub-scales: Socializing in the work place(5 items); Participation in community activities(16 items); Socializing in community activities(5 items); Contact with similar/different people(7 items); Assistance(17 items); Trust of institutions, corporations and other people(14 items); and Trust of intimate people (3 items). Although basic psychometric validation was performed on our original instrument (e.g., content and construct validity, internal consistency reliability), modern testing theory recommends a more comprehensive set of evaluations, including assessment of data quality, scaling assumptions, targeting, reliability, validity and responsiveness. Rasch measurement theory (RMT) is one of the Modern Test Theory methods that assesses the extent to which rigorous measurement is achieved. In the present work, our objective was to further evaluate the instrument using CTT and to use modern psychometric techniques to further validate the questionnaire and create version 2 (v2) using a new sample (N=224). We developed a Rasch model of the questionnaire to evaluate item fit statistics, item category thresholds, person separation index (PSI), local dependency, differential item functioning (DIF), unidimensionality and targeting and item locations. Assistance was the most problematic sub-scale of all, as item-to-total correlations ranged from 0.27 to 0.66. There were no disordered thresholds on any item, either examined as part of the overall score or as part of sub-scales. However, the analysis provided evidence of the need to modify some of the sub-scales as there was lack of support for unidimensionality or fit to the Rasch model. The Bridging Social Capital Questionnaire v2 has 61 items (compared to 67 in version 1). Our questionnaire may be suitable for adaptation to other immigrant groups in different countries.