We repeated the meta-analysis combining evidence for association based solely on the p value. Specifically, for each study we converted the two-sided p value to a z-statistic which was signed to reflect the direction of the association given the reference allele. Each z-score was then weighted; the squared weights were chosen to sum to 1 and each sample-specific weight was proportional to the square root of the effective number of individuals in the sample. Weighted z-statistics were summed across studies and the summary z-score converted to a two-sided p value.
