The Behavior Problems Inventory-Short Form for individuals with intellectual disabilities: Part II: Reliability and validity

Background The Behavior Problems Inventory-01 (BPI-01) is an informant-based behaviour rating instrument for intellectual disabilities (ID) with 49 items and three sub-scales: Self-injurious Behavior, Stereotyped Behavior and Aggressive/Destructive Behavior. The Behavior Problems Inventory-Short Form (BPI-S) is a BPI-01 spin-off with 30 items. Methods The psychometric properties of these two versions of the scale were computed using aggregated archival data from nine different sites in the USA, Wales, England, the Netherlands and Romania with a total of 1122 cases with a BPI-01 total score >0. Results The internal consistency of the BPI-01 and the BPI-S ranged from fair to excellent with the BPI-01 showing slightly stronger reliability. Construct validity (confirmatory and discriminant) was computed by comparing BPI sub-scale scores with the scores of four other behaviour rating scales (the Aberrant Behavior Checklist, the Diagnostic Assessment for the Severely Handicapped-II, the Nisonger Child Behavior Rating Form and the Inventory for Client and Agency Planning). Strong evidence for confirmatory and discriminant validity was found for both the BPI-01 and the BPI-S. Confirmatory fit indices for the BPI and the BPI-S were comparable and suggesting that the factor structures fit the data well. Conclusion In summary, both BPI versions were found to be equally sound psychometrically and can be endorsed for future use. However, independent future studies are needed to replicate the psychometrics of the BPI-S with new data