The Confirmatory Factor Analysis of the Original Brief Intellectual Disability Scale and Alternative Models

Brief Intellectual Disability Scale (BIDS) is a measure validated for identification of children with intellectual disabilities (IDs) in countries with low disability resources. Following the publication of the exploratory factor analysis of BIDS, the authors have documented the confirmatory factor analysis (CFA) of BIDS in this study.

A prospective cross-sectional study was conducted to document the CFA of the BIDS. Primary caregivers (N = 124) of children with ID were recruited and rated the BIDS. We used alternative fit indices for the evaluation of comparative fit index (CFI) and root mean square error of approximation (RMSEA) to evaluate the model fit. The 2-index fit strategy was used to select the best factor model.

The model fit index for the original 3-factor model and alternative 2-factor and 1-factor models with 9 items of the BIDS was under identified along with another 3-factor, 7-item model. Another 1-factor, 7-item model was identified but did not satisfy the 2-index fit strategy. A short version of the scale with a 2-factor and 7-item model of BIDS presented the best fit indices of CFI = 0.952 and RMSEA = 0.069.

Although the original factor structure of BIDS was not confirmed in this study, another alternative a priori model for the construct validity of BIDS was confirmed. Therefore, the BIDS factor structure has been revised, refined, and trimmed to the final 2-factor, 7-item shorter version. Further documentation of the diagnostic accuracy, validity, and reliability of this shorter version of BDI is recommended.