“…Effect sizes (Cohen's d ) were then calculated using formulae from Lipsey & Wilson's meta‐analysis manual [24] adjusted for sample size, and effect size calculators corrected for sample size [25]. As information was available, effect sizes were calculated for 17 outcome variables, within the domains of alcohol consumption (age of first drink/intoxication, frequency of drinking, frequency of heavy drinking, frequency of intoxication, quantity per week/month, quantity per occasion, maximum quantity, previous night drinking, quantity by frequency index, composite measure, other), alcohol consequences (problems, hangovers), alcohol use disorder symptoms, other drug involvement (cigarette or illegal drug use or dependence) and a composite alcohol–drug index.…”