Assessing measurement invariance in questionnaires within latent trait models using item response theory

Using questionnaires or inventories. researchers often perform mean comparisons between different populations (e.g .• males vs. females) in order to draw inferences about actual differences in the constructs being measured. However, such comparisons are not meaningful unless the assessments obtained in each of the populations are conmesurable or invariant across populations. Most researchers simply assume that measuremnt invariance holds. However, the extent to which this assumption is a reasonable one for specific measures and specific populations should be tested empirically. Using item response theory, the present study shows how gender measurement invariance can be determined when. as is most common, a psychological construct is assessed by means of a questionnaire or inventory composed of categorical items. To illustrate our method, the Positive Problem Orientation scale of the Social Problem-Solving Inventory-Revised (D' Zurilla. Nezu & Maydeu-Olivares, 1996) was assessed and found to be reasonably gender invariant. whereas the Negative Problem Orientation scale was not

Improving Health-Related Quality of Life in Older African American and Non-Latino White Patients

OBJECTIVE: To compare the effect of problem solving therapy against a health-promotion intervention (dietary practices) on health-related quality of life (HRQOL) and examine if there is a differential effect on non-Latino Whites and African-Americans between the two interventions. This paper also explores participant characteristics (problem solving style and physical functioning) as potential predictors of HRQOL. METHODS: Secondary analysis of data from a randomized depression prevention trial involving 247 older adults (154 non-Latino Whites, 90 African-Americans, 3 Asians). Participants were randomly assigned to receive either problem solving therapy for primary care (PST-PC) or coaching in healthy dietary practices (DIET). RESULTS: Both PST-PC and DIET improved HRQOL over two years and did not differ significantly from each other. African-Americans in both conditions had greater improvements in mental health-related quality of life (MHRQOL) compared to non-Latino Whites. In addition, higher social problem solving and physical functioning were predictive of improved MHRQOL. CONCLUSIONS: PST-PC and DIET have the potential to improve health-related quality of life in a culturally relevant manner. Both hold promise as effective and potentially scalable interventions that could be generalized to highly disadvantaged populations in which little attention to HRQOL has been paid