Discriminant Construct Validity of ImPACTTM: A Companion Study

In a previous analysis of ImPACT scores relative to traditional neuropsychological tests (NP) and experimental tasks (Maerlender et al., 2010) we demonstrated convergent construct validity for the primary ImPACT test-score composites. A complete analysis of discriminant validity was not undertaken at that time. Here, test scores from the 54 collegiate football and hockey players were re-analyzed to specifically address the discriminant validity of the ImPACT composite scores using a multiply operationalized correlation matrix of multitrait multi-method data. In the method used here, discriminant validity is determined by obtaining non-significant correlations between a target score when correlated with the average of the other trait measurements (multiply-operationalized multitraitmono-method analysis). Results showed that the ImPACT Verbal Memory (p = .044), Visual Memory (p = .006), and Visual Motor Speed (p = .000) scores were highly correlated with composites of the other scores, while the Reaction Time composite demonstrated adequate discriminant validity (p = .145). In comparison all of the NP composites showed good discrimination (all p-values > .05, except for Reaction Time p = .05). Thus the apparent lack of discriminability between three of four composite scores in this sample raises questions about using ImPACT composite scores to support specific constructoriented interpretations. Taken together, the discriminant and convergent construct validity properties of ImPACT indicate construct sensitivity, but limited construct specificity.