Table 2.

 Intention to treat analysis, comparing mean change in numbers of students observed to use primary site from pre-test to post-test by group

	Control schools (n=26)	Intervention schools (n=25)	Group difference (95% CI)	P value
Pre-test
Mean (SD) use*	3.49 (2.82)	3.24 (2.83)	−0.25
Range of use	0-59	0-30
Intra-school correlation coefficient	0.30	0.40
Post-test
Mean (SD) use†	3.46 (2.69)	5.87 (4.70)	2.41
Range of use	0-34	0-47
Intra-school correlation coefficient	0.34	0.52
Change from pre-test to post-test
Mean change‡	−0.03 (2.78)	2.63 (4.26)	2.67 (0.65 to 4.68)	0.011

*Aggregate mean of observations on 16 days.

†Aggregate mean of observations on 14 days.

‡Difference calculated as post-test mean use minus pre-test mean use.