Incorrect Formula: In the Preliminary Communication entitled “Within-Person Across-Neuropsychological Test Variability and Incident Dementia” published in the August 20, 2008, issue of JAMA (2008;300:823-830), a formula was incorrectly presented. On page 825, at the bottom of column 1, the last 2 sentences in the paragraph should read “Variability =
where Zik is the kth cognitive test score for ith individual, k = 1, . . . , K. Here, K = 3 (FCSRT, WAIS-R Vocabulary, and WAIS-R Digit Symbol Substitution) and
is the individual's mean z-transformed score based on the 3 tests.
Incorrect Formula in: Within-Person Across-Neuropsychological Test Variability and Incident Dementia Prenatal Genome Testing Sparks Debate. JAMA. 2008;300(22):2610. doi:10.1001/jama.300.22.2610