Meta-analysis (Mantel-Haenszel, fixed effects) on 16 case-control association studies on NAT2 slow acetylator status and lung cancer. Test for heterogeneity χ2 (df 15) = 25.58 (p = 0.0426). The summary odds ratio (OR = 1.04, 95% CI, 0.96–1.14) is not significant. Meta-analysis (DerSimonian-Laird, random effects) is similar, with summary OR (1.05, 95% CI 0.93–1.19, estimated random effects variance = 0.02), likewise not significant. The confidence interval for each study is given by a horizontal line, and the point estimate is given by a square whose height is inversely proportional to the standard error of the estimate. The summary odds ratio is drawn as a diamond with horizontal limits at the confidence limits and width inversely proportional to its standard error.