ethnic variation by excluding persons with a mother tongue other than Finnish or Swedish (the two official languages in Finland). With respect to analyses on alcohol consumption, the populations were of substantial size thus giving enough power to detect even relatively small effects. Based on the power calculations we should have been able to detect effects that would explain <1% of the variation in alcohol consumption. The results showing a lack of significant association between alcohol consumption and OPRM1 polymorphism can thus be considered reliable, even though the variables used to estimate the alcohol consumption varied between the populations analyzed.
