| Since 50% of males aged 20 and older smoke cigarettes in Taiwan and 60% of them have no intention to quit in the near future, an investigation of the determinants of intention to quit smoking based on the Theory of Planned Behavior (TPB), an extension of the Theory of Reasoned Action (TRA), was conducted in males in the workplace in southern Taiwan. Subjects were randomly sampled from three workplaces. Those from a large public steel-manufacturing company were used for model building, and eligible male employees from two private auto-parts-manufacturing companies served to cross-validate the model. Data were collected by a self-administered questionnaire. Response rates in these three companies were excellent, 78%, 82%, and 83%, respectively. Eligible subjects were divided into three study samples: a learning sample from the public company and two test samples, one from the public company and the other from combining the two private companies. This yielded 531, 132, and 136 smokers, respectively.;Three predictors, priority of quitting, past behavior (previous quit attempt), and habit (nicotine dependence) were added to the TPB model. Models based on the learning sample were developed by both hierarchical regressions and structural equation modeling, where LISREL 8 with SIMPLIS commands was used. Pearson product-moment correlations, paired-t tests and measures of fit were provided as indices of model fit.;Results of this study showed that TPB based on the learning sample fit well in another random sample from the same workplace but less well in other workplaces. In all results, TPB predicted better than TRA. Perceived behavioral control was the best predictor in the TPB model and in all modified models. When priority of quitting was added to a model, prediction significantly improved. Past behavior had both direct and indirect effects on intention to quit, whereas habit had only an indirect effect The modified structure (TPB + Priority of quitting), including both direct effect and indirect effects, fit well in both test samples. A more complex structure (TPB + Priority of quitting + Past behavior + Habit) fit well only in its own workplace.;Detail discussions of the results and their implications were provided. |
