Methods
Participants
The students were selected from High schools by SimpleRandom Sampling. Altogether 25 schools were selected inCalcutta Metropolitan area. Out of these, 21 schools (84%)responded. In each school two grades (a.k.a. classes in India)were selected (grades IX and XI). The survey was conductedbetween September, 1998 and January, 1999.The staff members of Epidemiology & Bio-statisticsDepartment of Chittaranjan National Cancer Institutedistributed the survey instrument. It was a self-administeredpre-tested questionnaire containing 51 close and open-endeditems. The students answered the items using paper andpencils. The answers were coded and entered into a databasefor further analysis.
Plan of Analysis
Independent variables
Age in years, sex, type of school (government-administered or privately owned), types of productsadvertised on television, smoking status of friends, siblingsand parents, and whether the subjects chewed tobacco, eitheralone or in combination with smoking. The age variable wasfurther categorized into four groups. The variables smokingby friends and siblings were combined to create a newvariable labeled ‘peer smoking’. No student had a sister whosmoked. Hence, sibling smoking status for this paperindicates whether a brother was a smoker. Peers were labeledas nonsmokers only where neither brothers nor friends