Table 4.

Stability and homogeneity of norm scales.

	All friendship groups		Longitudinal friendship groups
	ICC [95% CI], p-value	M (SD)	ICC [95% CI], p-value	M (SD)
Baseline
Recreation norm	0.49 [0.33, 0.65], <0.001	1.95 (0.61)	0.56 [0.39, 0.73], <0.001	1.98 (0.62)
Condom norm	0.04 [0.00, 0.20], >0.10	1.53 (0.51)	0.05 [0.00, 0.23], 0.291	1.49 (0.49)
Drug norm	0.48 [0.32, 0.64], <0.001	2.08 (0.87)	0.41 [0.21, 0.60], <0.001	2.07 (0.83)
12 Months
Recreation norm	0.47 [0.28, 0.66], <0.001	1.96 (0.59)	0.54 [0.35, 0.73], <0.001	1.98 (0.62)
Condom norm	0.03 [0.00, 0.25], >0.10	1.64 (0.49)	0.10 [0.00, 0.31], >0.10	1.62 (0.51)
Drug norm	0.46 [0.27, 0.65], <0.001	2.15 (0.85)	0.49 [0.29, 0.69], <0.001	2.14 (0.85)

Note. ICC values range from 0 to 1, and reflect the percent of total variation due to between-cluster variation. ICC values of zero reflect high homogeneity with heterogeneity increasing to a maximum at ICC value of 1. Groups = 2 or more close friends including seed. All friendship groups = 167 respondents (57 groups) at baseline and 127 (55 groups) at 12 months. Longitudinal friendship groups (models effect of change in group membership over time) = 123 respondents at baseline and 105 respondents at 12 months (38 friendship groups at both time points). A small proportion of the friendship groups (10%) in our sample included both males and females. We examined ICC values for groups with and without mixed gender members and the results were extremely similar. Unless otherwise noted, data for all groups are reported.