In these scenarios, the known biological properties of the variants can prove to be useful in formulating a prioritization strategy. When selecting SNPs for further study after a GWAS, such as genotyping in a replication sample, investigators may choose to prioritize solely based on the statistical evidence for genotype–phenotype correlation; in other words use a single P-value threshold. If there are sufficient resources to select all SNPs above a maximum desired P-value, which could be determined by the combination of a minimum desired effect size and specification of statistical power under some reasonable transmission models, then prioritization by P-value alone is logical. When resources are limited, certain genes and genomic regions may be given higher priority, such as selecting all SNPs with P < 10−4 and SNPs in certain genes with P < 10−2. Because these ranges of P-values may involve many false positives, care should be used in determining the thresholds, and a careful evaluation of statistical power should be used to determine the goals of the study, such as specifying a desired minimum effect size. When the evidence
