Three alcohol consumption categories were generated and reflect frequency of alcohol intoxication. Categories indicate whether the participant (0) had ever been intoxicated (never), (1) had been intoxicated sometimes (i.e. seldom, sometimes when drinking), or (2) had been intoxicated often (i.e. every time drinking, always). Never intoxicated includes non-drinkers and those participants who responded ‘No’ to ‘Have you ever drank so much that you got drunk?’ Categories reflect alcohol intoxication because general alcohol use was not assessed. A binary category was created for any illicit drug consumption reflecting use or no use because wave 2 participants were only asked if they had ever tried marijuana or illicit drugs (e.g. amphetamine, heroin, ecstasy or ‘something similar ’) and were not asked to identify the drugs.
