Number of quit attempts was not normally distributed so the data were log transformed in an attempt to achieve the normality and satisfy homoscedasticity assumptions necessary for ANOVA, which were then sufficiently, but not perfectly, satisfied. rs7004381, rs4950, and rs13280604 showed a trend toward association with number of quit attempts in the singletons. For example, for rs7004381 individuals with AA genotype averaged 1.38 ±1.16 quit attempts versus 5.77 ± 2.22 in GG individuals; similarly at rs4950 individuals with GG genotype averaged 0.47 ± 0.27 quit attempts versus 4.38 ± 1.74 in AA individuals, and at rs13280604 individuals with CC genotype averaged 1.2 ± 0.82 quit attempts versus 5.81 ± 2.81 in AA genotype individuals. However, these failed to be significant due to a low response rate for this question which greatly reduced power (fewer than 100 individuals within current frequent smokers).
