Table 2. Estimated variance¹ in sports-related concussion, CARE CSC, 2014/15 to 2018/19 academic years.

	School-Level Risk Factors Included in Model (% Change from Null Model)
	Univariate Models				Multivariate Model
	No School-Level Factors in model	Sport Risk Index in Model	Division in Model	School Type in Model	All 3 Factors (Risk Index, Division, Type)
All Sports-Related Concussions (Competition and Practice Combined)
Within-School	2.14 (ref.)	2.17 (+1%)	2.14 (0%)	2.14 (0%)	2.17 (+1%)
Between-School	0.28 (ref.)	0.24 (-14%)	0.24 (-14%)	0.27 (-4%)	0.18 (-36%)
Competition Concussions Only
Within-School	1.47 (ref.)	1.45 (-1%)	1.47 (0%)	1.47 (0%)	1.44 (-2%)
Between-School	0.27 (ref.)	0.21 (-22%)	0.27 (0%)	0.25 (-7%)	0.18 (-33%)
Practice Concussions Only
Within-School	1.87 (ref.)	2.13 (+14%)	1.87 (0%)	1.87 (0%)	2.14 (+14%)
Between-School	0.33 (ref.)	0.30 (-9%)	0.24 (-27%)	0.31 (-6%)	0.19 (-42%)

¹Variance estimates from log-binomial regression model, includes random intercepts for school