Statistical analyses
Distributions of the incidences of suicidal ideation and
suicide attempts varied by gender; therefore, data obtained
from males and females were analyzed separately in all
analyses. Chi-square tests were used to examine the differences
between males and females in the lifetime prevalence
of alcohol drinking, cigarette smoking, and sexual inter-course (Table 1). Distribution of all variables was also presented
by gender (Table 2). Descriptive analyses were performed
using a chi-square test and univariate logistic regression
analysis to investigate the associations between
early initiation of problem behaviors and suicidal behaviors
(Table 3). To avoid any possible confounding effects among
our primary variables, multivariate logistic regression analyses
were conducted and included all covariates (Table 4).
Multivariate analyses were also performed to determine
the effect of concurrent participation in these problem
behaviors on each outcome (Table 5). The significance level
was set at p < 0.05. All analyses were performed using SAS
statistical software (version 9.1).