title: Do balanced scales assess bipolar constructs? The case of the STAI scales.
abstract: Balanced scales, that is, scales based on items whose content is either negatively or positively polarized, are often used in the hope of measuring a bipolar construct. Research has shown that usually balanced scales do not yield 1-dimensional measurements. This threatens their construct validity. The authors show how to test bipolarity while accounting for method effects. This is demonstrated on a data set of state and trait anxiety measured with the State-Trait Anxiety Inventory (STAI; C. D. Spielberger, R. L. Gorsuch, R. Lushene, P. R. Vagg, & G. A. Jacobs, 1983) scales. Taking a test-retest perspective, assuming temporally stable method effects, the authors tested the bipolarity of the temporal change through suitable constraints specified in a structural equation model adapted from S. Vautier, R. Steyer, and A. Boomsma (2008). The model fit the data closely, chi(2)(13, N = 888) = 20.75, p = .07. Thus, the state and trait scales seem to measure bipolar constructs plus temporally stable method effects. Parameter estimates suggest reliable change scores for the state anxiety scale (rho = .90) and specific method effects for the state and trait scales of the STAI.
authors.affiliation: Vautier, Department of Psychology, Universite de Toulouse, Toulouse, France. vautier@univ-tlse2.fr
authors.forename: Stéphane
authors.initials: S
authors.lastname: Vautier
authors.forename: Steffi
authors.initials: S
authors.lastname: Pohl
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000523:psychology; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007206:Individuality; D008297:Male; D015233:Models, Statistical; D010555:Personality Inventory / Q000706:statistics & numerical data*; D011594:Psychometrics; D015203:Reproducibility of Results; D013315:Stress, Psychological; D011795:Surveys and Questionnaires