Transtheoretical Model (TTM) questionnaire for Iranian smoking cessation: validity and reliability

Successful strategies implementing smoking cessation are account for cardinal investments in tobacco control programs. One of the models that has been utilized in smoking cessation is the transtheoreticlal model (TTM). This study aimed to assess the psychometric properties of the version of transtheoretical model (TTM) questionnaire for Iranian smokers. This was a methodological study among male smokers who worked in factories in Tehran. In this study, the short form of TTM questionnaire was evaluated in term of validity and reliability. The factor analysis was conducted to test validity. The internal consistency and stability of the questionnaire was tested using Cranach’s alpha coefficient and Infraclass Correlation Coefficient (ICC). Male smokers participated with mean age 36.51 ± 7.94 years. The result from exploratory analysis (N=150) showed 9 factors with 75.3% of cumulative variance. The results obtained from confirmatory factor analysis (N=150) revealed that the data were fit to the model (&chi2/df =1.61, p< 0.001, RMSEA =0.06, GFI = 0.91, CFI =0.93). Assessment Cronbach’s alpha indicated acceptable internal consistency (0.76) and also correlation implied a satisfactory stability (0.75). The findings of this study indicated the Iranian version of the instrument had satisfactory psychometric properties and could be applied in studying behavior change and designing smoking cessation interventions.