SNP allele frequency assessments display modest variability. Standard errors for the variation among the four replicate studies of each DNA pool were +/- 0.035. Standard error for the variation among the pools studied for each phenotype group was +/- 0.028. Previous validating studies for these arrays have also revealed good fits between individual and pooled genotyping, with 0.95 correlations between pooled and individually-determined genotype frequencies [21-31]. The observed pool-to-pool standard deviations from these datasets thus indicate 0.94 and 1.0 power to detect 5 and 10% allele frequency differences with α = 0.05 in nicotine dependent vs control comparisons. We have 0.45 and 0.95 power to detect 5 and 10% allele frequency differences in successful vs unsuccessful quitters. Additional false negative results are likely to derive from the additional stringent requirement that four other samples each provide supporting evidence for the nicotine dependent vs control comparisons noted here.
