Table 2.

Analysis of variance of both CT and MRI use rates (groups are the procedures)

	Source	SS	Per cent	df	MS	F	Prob>F
MRI	Between groups	0.030646	90	31	0.000989	265.17	0
	Within groups	0.003571	10	958	3.73E-06
	Total	0.03422	100	989	3.5E-05
CT	Between groups	0.005658	71	27	0.00021	74.94	0
	Within groups	0.002324	29	831	2.80E-06
	Total	0.00798	100	858	9.30E-06

MRI Bartlett's test for equal variances: χ² (31)=4.1e+03 Prob>χ²=0.000

CT Bartlett's test for equal variances: χ² (27)=1.5e+03 Prob>χ²=0.000