Abstract
BACKGROUND: As previous studies suggest that the theory of planned behavior (TPB) is open to the inclusion of further predictors, identifying a number of additional background variables within the context of the TPB may help improve the predictive power of the theory. The purpose of this study is to incorporate environmental variables as precursor background variables of the TPB to predict quitting-related intentions. METHODS: This study consists of two sub-studies. Sub-study 1 and 2 analyzed different data sets and were conducted using the similar methodology for the comparison. A total of 395 Texas adult smokers (sub-study 1) and 379 university student smokers (sub-study 2) were analyzed using multiple structural equation modeling. RESULTS: The extent of agreement with regulating smoking in public places had positive indirect effects on intention to quit through subjective norm among both Texas adult smokers (β = 0.03, p < .01) and university students (β = 0.01, p < .05), and through attitude among Texas adult smokers only (β = 0.02, p < .01). The number of smokers among 5 closest friends had negative indirect effect on intention to take measures to quit through subjective norm among Texas adult smokers (β = - 0.02, p < .05). CONCLUSIONS: The results of this study indicate that environmental variables need to be considered as precursor background variables of the TPB to predict quitting-related intentions.