This meta-analysis also showed that multiple-item measures of subjective norms were a stronger predictor of intentions than single-item measures, which may explain our results. Although this was also found in an earlier study (Bledsoe, 2006), it is unclear why Fluoro Sorafenib self-efficacy was not significantly associated with intention after controlling for the other predictors in the model. A meta-analysis showed that attitudes, subjective norms, self-efficacy, and intention explain 27% of the variance in behavior (Armitage & Conner, 2001). Our explained variance was similar for quit attempts (28%), but much higher for quit success (50%). This may be caused by the strong direct effect from self-efficacy on quit success, which is consistent with predictions of social cognitive models.

Consistent with earlier studies (Borland et al., 2010; Hyland et al., 2006; Zhou et al., 2009), intention to quit was a stronger predictor of quit attempts than of quit success. Earlier studies that examined the direct effects of smoke-free legislation on smoking behavior found positive effects in some jurisdictions and not in others (Bajoga et al., 2011; Callinan et al., 2010). Earlier ITC studies have also found inconsistent evidence of an effect of smoke-free legislation on smoking cessation (Cooper, Borland, Yong, & Hyland, 2010; Fong, Hyland, et al., 2006; Hyland, Hassan, et al., 2009; Nagelhout, De Vries et al., 2012). The current study sheds some light on psychosocial factors that mediate the effects of smoke-free legislation on smoking cessation, that is, if the legislation is not supported by smokers and smokers do not change their attitudes about quitting, no effects on cessation are to be expected.

However, behavioral factors like implementing voluntary smoking bans in homes and cars and complying with smoke-free legislation might also explain why smoke-free legislation stimulates smoking cessation in some individuals and not in others. Moreover, implementation characteristics of the smoke-free legislation may influence whether smoke-free legislation increases Cilengitide smoking cessation. It is, for example, reported that support for smoke-free legislation increases more after the implementation of comprehensive than after the implementation of partial smoke-free legislation (Mons et al., 2012; Thrasher, Swayampakala, et al., 2010). Comprehensive smoke-free legislation may therefore lead to more smoking cessation than partial legislation. Also, smoke-free legislation that is implemented with accompanying media attention may lead to more support and harm awareness (Thrasher et al., 2011; Villalobos et al., 2010).