Development and validation of discriminant functions for the Strong Interest Inventory

This study compared the relative accuracy of (a) single Occupational Scale (OS) scores on the Strong Interest Inventory (SII) and (b) multiple-predictor scoring functions for discriminating members of nine occupations from people-in-general. The functions were constructed using discriminant function analysis with 4797 adults drawn from criterion samples for the 1985 SII. The analyses included Basic Interest Scale (BIS) scores only or combinations of OSs and BISs. Two subsequent analyses, one of which was cross-validation using 1302 young adults with little work experience, also were conducted. Results indicated that BIS-only functions yielded hit rates comparable to single OSs, and functions that combined OSs and BISs generally produced slight improvements in accuracy. These findings are potentially relevant for future SII scale development decisions.