At age 14, participants reported via a postal questionnaire if they smoked and how much using eight options: ‘Never’; ‘I have tried once’; ‘I have tried twice or more’; ‘I smoke occasionally’; ‘I smoke about twice a week’; ‘I smoke between 1–5 cigarettes a day’; ‘I smoke between 6–10 cigarettes a day’; ‘I smoke more than 10 cigarettes a day’. As before(41), adolescents who never smoked or had smoked once/twice in their lives were classified as non-smokers; subjects reporting they had been smoking occasionally or about twice per week as occasional-smokers; and the rest as regular-smokers.
