Fig. 4From: Combined genetic influence of the nicotinic receptor gene cluster CHRNA5/A3/B4 on nicotine dependenceDistribution of the residuals probabilities of nicotine dependence score (FTND 0 or 4~â10) associated with each of rs880395Â (a), rs16969968Â (b), rs1948Â (c) and rs4887074Â (d) alleles. To test heteroskedasticity of the residuals, the Breusch-Pagan test was performed. Among four SNPs, rs16969968 and rs4887074 are significantly associated with the variability of the residuals (**pâ<â.01, ***pâ<â.001)Back to article page