Replication studies should be conducted in an independent dataset drawn from the same population as the GWAS, in an attempt to confirm the effect in the GWAS target population. Once an effect is confirmed in the target population, other populations may be sampled to determine if the SNP has an ethnic-specific effect. Replication of a significant result in an additional population is sometimes referred to as generalization, meaning the genetic effect is of general relevance to multiple human populations.
