Chunk #22 — 2. Methods — 2.2. Variable definitions — 2.2.4. Covariates — Offspring perception of sibling behaviors

Source

Parent, sibling and peer influences on smoking initiation, regular smoking and nicotine dependence. Results from a genetically informative design.

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yes

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Response options for both the friends and school peer questions were on a 7 point scale from `none', `just a few', `a quarter', `half', `three-quarters', `almost all' to `all'. We collapsed across categories to create a 3-level variable for friends use as none, a few and a quarter or more. Peer use was also modeled as a 3 level variable: none/a few, quarter to one-half and one-half or more.