The primary outcome measure identified for this analysis was the presence or absence of any s allele, consistent with past evaluations in this area (e.g., Feinn et al., 2005). An odds ratio (OR) was used as the effect size measure for this analysis because variables were dichotomous in nature. ORs were calculated for each study using the frequencies of s alleles in the alcohol dependent and control groups, based on the following formula: OR=p/(1−p)q/(1−q), where p represents the proportion of alcohol dependent participants with at least 1 s allele and q represents the proportion of control participants with at least 1 s allele. Thus, the ORs reported reflect the ratio of the likelihood of possessing at least one s allele in the alcohol dependent group to the likelihood of possessing at least one s allele in the control group (i.e., an OR greater than 1 reflects a higher likelihood of possessing an s allele in the alcohol dependent group). Random-effects models were used for effect size estimates. The use of a random-effects model is appropriate when the aim is to
