Rasch Measurement Theory's contribution to the psychometric properties of a co-created measure of health and wellness for Indigenous children and youth

Abstract

ObjectivesTo determine how Rasch Measurement Theory (RMT) methods can be used to assess the psychometric properties of the Aaniish Naa Gegii: the Children's Health and Wellbeing Measure (ACHWM) and Qanuippit. Study Design and SettingIndigenous children aged 8–18 years, from five communities, completed the 62-item ACHWM. We applied RMT methods to ACHWM data from 401 children (mean age 13.4 ± 3.4 years; 51% male) from across Ontario to examine how well the items captured the full range (±3 logit) of the concept of interest in each domain, targeted the needs of Indigenous children, and met the criteria for unidimensional and invariant measurement. ResultsRMT results indicated moderate-fit overall fit (raw χ2 = 809, P < 0.001). This model was further improved by aggregating the five response categories into three categories. All four domains showed excellent overall fit to the Rasch model (P > 0.05), with items covering between −4.51 and 6.02 logit, with no gaps along the theoretical continua. ConclusionThis study provides evidence that a set of conceptually derived items was able to produce a measure that fits the Rasch model. These results aid our understanding of wellness by establishing the clinical meaning of the scale scores.