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Fig. 5 | BMC Genomics

Fig. 5

From: Power estimation and sample size determination for replication studies of genome-wide association studies

Fig. 5

The relationship between estimated average power \(\bar {\eta }_{\textit {EB}}^{(2)}\) and the sample size of the replication study n (2) for 6 diseases of the WTCCC dataset: a coronary artery disease, b Crohn’s disease, c hypertension, d rheumatoid arthritis, e type 1 diabetes, f type 2 diabetes. The Control-to-Case ratio of the replication study is set to 1. The significance levels used in the primary study and the replication study are α 1=5×10−8 and α 2=5×10−6, respectively. As a comparison, the relationship between \(\bar {\beta }^{(2)}\left (\hat {\mu }^{(1)}\right)\) and n (2) are also shown in the figure. For a fixed n (2), \(\bar {\beta }^{(2)}\left (\hat {\mu }^{(1)}\right)\) is much larger than \(\bar {\eta }_{\textit {EB}}^{(2)}\). In (a) and (f), \(\bar {\beta }^{(2)}\left (\hat {\mu }_{\textit {meta}}\right)\) is the average power estimator by plugging the log-odds ratio obtained from high power meta-analysis study: CARDIoGRAM GWAS [22] and DIAGRAM GWAS [23], respectively. It can be shown that \(\bar {\eta }_{\textit {EB}}^{(2)}\) is close to \(\bar {\beta }^{(2)}\left (\hat {\mu }_{\textit {meta}}\right)\)

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