Perceived Effectiveness of Stop Smoking Interventions: Impact of Presenting Evidence Using Numbers, Visual Displays, and Different Timeframes

This study investigates the impact of visual and numerical representations of effectiveness and different lengths of follow-up upon the perceived effectiveness of stop smoking interventions. This study entails two between-subjects experiments with smokers from the general population. In Experiment 1, U.K. smokers (n = 318) viewed information about a stop smoking intervention that included (a) no effectiveness information, (b) standard numerical effectiveness information, or (c) numerical and visual absolute effectiveness information. In Experiment 2, U.K. smokers (n = 320) viewed numerical and visual absolute effectiveness information about a stop smoking intervention showing either the short-term (1-month) or the long-term (12-month) quit rate with and without intervention. Outcome measures included perceived effectiveness of stop smoking interventions and intentions to use them. In Experiment 1, numerical and visual absolute effectiveness information compared with no effectiveness information resulted in greater perceived effectiveness (Scheffe test, p = .033, Cohen's d = 0.36) and intentions to use stop smoking interventions (Scheffe test, p = .012, d = 0.43). No differences were detected between standard numerical effectiveness information and no effectiveness information. In Experiment 2, the short-term quit rate compared with long-term quit rate resulted in greater perceived effectiveness, t(318) = 3.2, p = .002, d = 0.35, but not significantly greater intentions to use stop smoking interventions, t(318) = 1.59, p = .11, d = 0.18. Presenting numerical and visual absolute effectiveness information about the short-term effectiveness of stop smoking interventions may increase the use of stop smoking interventions.