Bi-factor analyses of the Brief Test of Adult Cognition by Telephone

Abstract

Telephone cognitive batteries are useful for large-scale screening and epidemiological studies, but their brevity and lack of content depth may cause psychometric limitations that hinder their utility. The current study addressed some of these limitations by rescaling the Brief Test of Adult Cognition by Telephone (BTACT; Tun & Lachman, 2006) using modern psychometric methods. Archival data were obtained from a national sample of 4,212 28 to 84-year-old volunteers in the National Survey of Midlife Development in the United States (Ryff et al., 2007) Cognitive Project (Ryff & Lachman, 2007). We fit a bi-factor model to a combination of item-level, subscale-level, and scale-level data. The best fitting model contained a general factor and secondary factors capturing test-specific method effects or residual correlations for Number Series, Red/Green Test, and the Rey Auditory Verbal Learning Test. Factor scores generated from this model were compared with conventional BTACT scores. Important score differences (i.e., >0.3 standard deviation units) were found in 28% of the sample. The bi-factor scores demonstrated slightly superior validity than conventional BTACT scores when judged against a number of clinical and demographic criterion variables. Modern psychometric approaches to scoring the BTACT have the benefit of linear scaling and a modest criterion validity advantage.