Reliability and Construct Validity of the Malay Version of Theory of Planned Behaviour (TPB) for Smoking Cessation

Objective: The aim of this study was to evaluate the psychometric properties of the Malay translated version of the Theory of Planned Behavior (TPB) intention to quit smoking questionnaire. Methods: A cross-sectional study was performed involving 185 male smokers. The forward-backward translation procedure was adopted to translate the questionnaire from English to Malay. The internal consistency and stability were assessed using Cronbach’s alpha and a correlation analysis and Exploratory Factor Analysis was conducted. Result: The translated questionnaire showed good internal consistency with Cronbach’s alpha values of 0.86, 0.64, 0.74 and 0.90 for each of the four respective factors. The test-retest reliability revealed acceptable stability, with Spearman’s correlation coefficients ranging from low to moderate (r>0.30-0.50) and a satisfactory inter class correlation coefficient (ICCs). The construct validity achieved an acceptable factor loading for each construct which ranged from 0.40 to 0.90. Conclusion: The current study provided psychometric evidence for an appropriate, reliable and valid tool of TPB Malay version. This questionnaire could be applied in evaluating smoking cessation interventions in Malaysia.