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Ghisletta, P., J.R. Nesselroade, David Featherman, and J.W. Rowe. 2002. "Structure and Predictive Power of Intraindividual Variability in Health and Activity Measures." Swiss Journal of Psychology, 61(2): 73-83.
Intraindividual variability has been shown in many studies to be well structured over time and capable of predicting a wide range of behaviors. This study provides analyses of weekly variations of health and activity measurements in a sample (N = 52) of elderly persons (mean age = 77.5, SD = 7.2). The three main goals and results entailed: 1. Assessing the reliable nature of a health and an activity factor through a metric invariant confirmatory factor model; 2. Assessing the independence of intraindividual variability from level information and showing that the amount of intra-person variability during the first and second half of data collection correlate very highly; 3. Showing that intraindividual variability information of health and activity scores is superior to level information in predicting mortality.