Table 2.

Generalized estimating equation analysis of the effectiveness of the intervention for improving the knowledge of substance use prevention (N=1065). Model: Y=β0+β1(group)+β2(time)+β3(group×time).

Parameter	Estimate（β）	SE	P value	95% CI
Intercept	.731	0.0074	<.001	0.716 to 0.745
Group (experimental vs controla)	–.024	0.0112	.03	–0.046 to –0.002
Time (follow-up vs baselinea)	.030	0.0046	<.001	0.021 to 0.039
Group×time	.053	0.0082	<.001	0.037 to 0.069

^aReference group.