Figure 1. The Efficacy of e-Cigarettes on Smoking Cessation
df, degrees of freedom; EC, electronic cigarette; M-H, Mantel-Haenszel method for calculating risk ratio.
Reprinted from McRobbie H et al, Electronic cigarettes for smoking cessation and reduction, Cochrane Database Syst Rev, Vol 12; CD010216, Copyright © (2014), with permission from The Cochrane Collaboration.