Confirmatory factor analysis of the Autonomy over Tobacco Scale (AUTOS) in adults

Abstract

IntroductionThe Autonomy over Tobacco Scale (AUTOS), a 12-item self-administered questionnaire, was designed to measure autonomy in three correlated lower-order symptom domains: withdrawal, psychological dependence, and cue-induced craving. The factor structure of the AUTOS remains an open question; confirmatory analyses in adolescents supported the hierarchical structure, while exploratory analyses in adolescents and adults yield single-factor solutions. Here we seek to determine whether the hypothesized hierarchical structure is valid in adult smokers. MethodsThe AUTOS was administered to two independent convenience samples of adult current smokers: a calibration sample recruited in the US for online studies, and a confirmation sample drawn from the prospective Nicotine Dependence in Teens study in Montreal. We tested competing hierarchical and single-factor models using the robust weighted least-squares (WLSMV) estimation method. ResultsA single-factor model that allowed correlated error variances between theoretically related items fit well in the calibration sample (n=434), χ2SB(52)=165.71; χ2/df=3.19; SRMR=0.03; CFI=0.96; NNFI=0.95; RMSEA=0.07 (95% CI: 0.06, 0.08). Reliability of the single factor was high (ωB=0.92) and construct validity was adequate. In the confirmation sample (n=335), a similar model fit well:χ2SB(53)=126.94; χ2/df=2.44; SRMR=0.04; CFI=0.95; NNFI=0.93; RMSEA=0.07 (95% CI: 0.05, 0.08). Reliability of the single factor was again high (ωB=0.92) and construct validity was adequate. ConclusionThe AUTOS is unidimensional in adult smokers.