The decision between candidate gene and GWAS is complicated by the logistics of genotyping. Genotyping is far more efficient and low cost when conducted on a large scale. Accordingly, the cost per genotype falls exponentially as the number of genotypes increases. High throughput genotyping using GWAS arrays is 1000 times more cost-efficient than small scale genotyping. Thus, even if a social scientist has no interest in analyzing all 1 million markers across the genome, it may be more cost-efficient to genotype a GWAS chip on all participants, so that genotypes are available across the a priori genes of interest, as well as for future genes of interest that may emerge. This also facilitates collaborations and attempts at replication, since genes of interest from different groups will already be available in the proverbial “GWAS bank.” For this reason, it may be reasonable and cost-efficient to genotype a GWAS chip, even if a more targeted candidate gene strategy is proposed. Currently, GWAS chips cost approximately $200 to purchase and $100 to process, which may still make them out of reach for many
