Comparison of Apple iTunes App Store or Google Play store rank (vertical axis, inverse scale) with the quality of the underlying evidence on which 47 smoking cessation apps are based. The higher the evidence score (x axis), the more the app conforms to relevant guidelines from the US Preventive Service Task Force. The lower the store rank (y axis, reverse scale), the higher the app is listed in the App Store or Google Play store. The brown ellipse shows a cluster of low quality, high ranked apps, while the blue ellipse shows a cluster of high quality, low ranked apps. Author’s analysis based on data from Abroms et al.