Figure 1.

A meta-analytic summary of the risk of cancer at four sites due to smoking, based on case-control studies from the Surgeon-General's reports of 1964 and 1982. Each bar shows a 95% confidence interval of the summary odds ratio, with the point estimate and 95% confidence limits marked. The width of each bar is proportional to the total sample size of the studies included in the meta-analysis for that site.