Measurement Properties of the Symptom Impact Inventory

The purpose of this study is to evaluate the measurement properties of the Symptom Impact Inventory using both psychometric and Rasch analyses. This inventory is designed for generally healthy midlife women. The sample included 340 midlife women aged 45-65 representing two studies. The first study involved Black and White employed sedentary women (n = 161) who volunteered for a walking intervention. The second study of migration and health included women who were recent immigrants from the former Soviet Union (n = 179). The women reported experiencing an average of 13.44 symptoms (S.D.=7.88) with a range of 1 to 32. Principal components analysis identified 5 components in this sample. Rasch measurement analysis found excellent model fit for the Symptom Impact Inventory with only 2 symptoms, Decreased appetite and Decreased sexual desire or interest, unstable in scale dimensionality analyses. Person and item parameters were reliable, and comparisons with groups known to differ on symptom reporting provided substantial validity. Although the two sample groups differed significantly on most demographic characteristics, a cross-cultural comparison found the scale structure remarkably robust.