title: Confirmatory factor analysis of the Autonomy over Tobacco Scale (AUTOS) in adults.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  The 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.
  
  
  RESULTS
  A single-factor model that allowed correlated error variances between theoretically related items fit well in the calibration sample (n = 434), χ(2)SB(52) = 165.71; χ(2)/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:χ(2)SB(53) = 126.94; χ(2)/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.
  
  
  CONCLUSIONS
  The AUTOS is unidimensional in adult smokers.
authors.affiliation: Department of Family Medicine and Community Health, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, United States. Electronic address: Robert.Wellman@umassmed.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wellman
authors.affiliation: Department of Family Medicine and Community Health, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, United States. Electronic address: joseph.difranza@umassmemorial.org.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: DiFranza
authors.affiliation: Department of Social and Preventive Medicine, University of Montréal, 3875 St. Urbain, 1st Floor, Montreal, Quebec, H2W 1V1, Canada; Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Tour St-Antoine, 850 St-Denis, Montreal, Quebec, H2X 0A9, Canada. Electronic address: jennifer.oloughlin@umontreal.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Loughlin
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D066249:Craving; D003463:Cues; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D008922:Mississippi / Q000453:epidemiology; D011594:Psychometrics; D015203:Reproducibility of Results; D013375:Substance Withdrawal Syndrome / Q000453:epidemiology*; D011795:Surveys and Questionnaires / Q000592:standards*; D014029:Tobacco Use Disorder / Q000453:epidemiology*; D055815:Young Adult
keywords: AUTOS; Adults; Autonomy over tobacco; CFA; Nicotine dependence; Smoking