Forest plot of ever smoking of any product and squamous – part 1. Table 5 presents the results of a main meta-analysis for squamous based on 102 relative risk (RR) and 95% confidence interval (CI) estimates for ever smoking of any product (or cigarettes if any product not available). The individual study estimates are shown numerically and graphically on a logarithmic scale in Figures 6, 7. The studies are sorted in order of sex within study reference (REF) within start year of study (START) within continent (CONT). In the graphical representation individual RRs are indicated by a solid square, with the area of the square proportional to the weight (inverse-variance of log RR). Arrows indicate where the CI extends outside the range allocated. For study SCHWAR separate estimates, within sex, are shown for whites then blacks.