The French Version of the DABS: an IRT analysis

Background. Adaptive Behavior (AB) is an essential component of everyday functioning, and limitations in conceptual, social, and/or practical skills are among the diagnostic criteria for intellectual disability (ID). During the ID diagnostic process, despite the importance of this feature, standardized assessments of AB appear to be used less systematically than assessments of intellectual functioning. This may be explained by the lack of instruments specifically developed for diagnostic purposes, particularly in French-speaking countries in Europe. The aim of this study was to test the French adaptation of the DABS using Item Response Theory (IRT).
Method. The sample consisted of 885 participants living in Belgium, France, and Switzerland, stratified by age, sex, and level of ID. IRT analyses (graded response models) were conducted separately for each AB domain using IRTPRO 6.0.
Findings. Structural equation models indicated no substantial departure from unidimensionality. All three graded response models showed good fit, with RMSEA values below .06. The Total Information Curve for each domain and age version confirmed that the instrument is particularly informative at levels of AB around the cut-off for significant limitations in adaptive functioning.
Conclusions. The results of this study, comparable to those obtained by the authors of the original DABS, support the quality of the calibration of the French adaptation of the instrument.