Based on the piecewise effect model of risk with age
(time), we conducted univariate analyses of the effects of
socio-demographic background and family characteristics
on the risk of daily smoking initiation. For each predictor,
results from the main-effect model or the interactive model
(with time) were included depending on whether the time
interaction term was significant. If the time interaction term
was significant at the .10 level, the coefficients of both the
main effect and the interaction terms are reported for that
predictor. Otherwise, the coefficient of the main effect of
the predictor from the main effect model is reported.
To examine the effects of each predictor independent of
other predictors in the same domain, significant predictors
(main effects or interactions with time) within the same
domain (i.e., socio-demographic background, family smoking,
family processes, and parental attitudes and norms
toward smoking) were then entered simultaneously to obtain
four Single Domain Models (socio-demographic background,
family smoking, family processes, and parental
attitudes/norms toward smoking). Based on the single domain
models, we examined the relationships among family
smoking, family processes, and parental attitudes/norms and
the risk of daily smoking initiation in Multiple Domain
Models. Model 1 contained all socio-demographic variables.
Model 2 included all variables in Model 1 and all family smoking variables. Model 3 included all variables in
Model 2 and all family process variables. Model 4 included
all variables in Model 2 and parental attitudes and norms
toward smoking variables. Finally, we examined the interactions
between gender and family predictors. Significant
interactions indicate significant gender differences in the
effects of the particular family predictors in affecting daily
smoking initiation.