A critical item analysis of the QABF: development of a short form assessment instrument

Due to the relative inability of individuals with intellectual disabilities (ID) to provide an accurate and reliable self-report, assessment in this population is more difficult than with individuals in the general population. As a result, assessment procedures must be adjusted to compensate for the relative lack of information that the individual may be able to provide and rely more on the behavioral expression of communication. One method commonly used is the indirect functional assessment that utilizes behavior rating scales developed to gather behavioral data in a short time. One of the few empirically derived and psychometrically sound scales is the Questions About Behavioral Function (QABF), a 25-item questionnaire designed to rate specific behavioral functions and maintaining variables. The purpose of this study was to use both exploratory and confirmatory factor analytic procedures to examine the psychometric properties of the QABF, conduct an item analysis, and determine if a short form version could be developed that is both psychometrically valid and reliable, and clinically useful. Results of the item selection procedure indicated that the original 25 items could be reduced to 15. Evaluation of the 15-item short form showed that the QABF-SF maintained the original five-factor structure of the original form, while maintaining an equivalent degree of reliability and validity. The QABF-SF appears to be a useful tool to aid clinicians in the brief functional assessment of behavior in individuals with ID.