Parallel but not equivalent: Challenges and solutions for repeated assessment of cognition over time
Gross, Alden L.
Rebok, George W.
Crane, Paul K.
Parisi, Jeanine M.
Carlson, Michelle C.
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CitationGross, Alden L., Sharon K. Inouye, George W. Rebok, Jason Brandt, Paul K. Crane, Jeanine M. Parisi, Doug Tommet, Karen Bandeen-Roche, Michelle C. Carlson, and Richard N. Jones. 2012. Parallel but Not Equivalent: Challenges and Solutions for Repeated Assessment of Cognition over Time. Journal of Clinical and Experimental Neuropsychology 34, no. 7 : 758–772. doi:10.1080/13803395.2012.681628.
AbstractOBJECTIVE: Analyses of individual differences in change may be unintentionally biased when versions of a neuropsychological test used at different follow-ups are not of equivalent difficulty. This study's objective was to compare mean, linear, and equipercentile equating methods and demonstrate their utility in longitudinal research.
STUDY DESIGN AND SETTING:
The Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE, N = 1,401) study is a longitudinal randomized trial of cognitive training. The Alzheimer's Disease Neuroimaging Initiative (ADNI, n = 819) is an observational cohort study. Nonequivalent alternate versions of the Auditory Verbal Learning Test (AVLT) were administered in both studies.
Using visual displays, raw and mean-equated AVLT scores in both studies showed obvious nonlinear trajectories in reference groups that should show minimal change and poor equivalence over time (ps ≤ .001), and raw scores demonstrated poor fits in models of within-person change (root mean square errors of approximation, RMSEAs > 0.12). Linear and equipercentile equating produced more similar means in reference groups (ps ≥ .09) and performed better in growth models (RMSEAs < 0.05).
Equipercentile equating is the preferred equating method because it accommodates tests more difficult than a reference test at different percentiles of performance and performs well in models of within-person trajectory. The method has broad applications in both clinical and research settings to enhance the ability to use nonequivalent test forms.
Citable link to this pagehttp://nrs.harvard.edu/urn-3:HUL.InstRepos:33751436
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