Figure 7.

Funnel plot on association between RARβ promoter hypermethylation and oral cancer risk (control vs case, unmethylation vs methylation). s.e.of: logOR, standard error of log OR. The funnel plot is applied to evaluate the publication bias among included studies. The horizontal axis represents the effect size of each included study. The area enclosed by the 2 diagonal lines simulates the 95%CIs. If the dot is located out the 95%CIs, publication bias may exist among studies. In addition, these dots that represent included studies should be symmetrical and be distributed on both sides of the angular bisector, which demonstrates no publication bias is found. From the funnel plot of Begg's test, we will acquire a P value. From the results, the P value of the funnel plot was > 0.05. Therefore, no significant publication bias was found in this analysis. Log OR = standard error of log odds ratio, RARβ = retinoic acid receptor beta, s.e.of: log OR = standard error of log odds ratio.