Table 3.

Estimated type I error rates for testing the equality of the indices under a simulation model based on normal distributions and skewed distribution (in parentheses). The symbols in the table heading are the following simulation parameters: AUC - is the degree of separation between the distribution of FP and TP ratings; b - is the ratio of the standard deviation of FP ratings to that of TP ratings; λ - is the average number of FP marks per subject; ν - is the average proportion of the marked lesions t - is the number of lesions on an actually positive subject. The estimates of the type I error rate are based on 10 000 simulations which results in a maximum possible estimation standard error of 0.005.

			AUC=0.5			AUC=0.7			AUC=0.9
			λ=1.0			λ=1.0			λ=1.0
			θ	A1	A2	θ	A1	A2	θ	A1	A2
1∕b	t	υ
1	1	0.5	0.055	0.057	0.055	0.056	0.052	0.053	0.051	0.050	0.051
			(0.056)	(0.058)	(0.058)	(0.057)	(0.053)	(0.054)	(0.051)	(0.051)	(0.050)
		0.9	0.048	0.052	0.053	0.051	0.053	0.052	0.041	0.046	0.050
			(0.048)	(0.053)	(0.052)	(0.052)	(0.055)	(0.055)	(0.042)	(0.047)	(0.048)
	3	0.5	0.055	0.056	0.054	0.053	0.053	0.051	0.042	0.046	0.049
			(0.057)	(0.056)	(0.057)	(0.054)	(0.051)	(0.052)	(0.044)	(0.047)	(0.048)
		0.9	0.046	0.054	0.055	0.037	0.051	0.050	0.002	0.025	0.031
			(0.053)	(0.055)	(0.055)	(0.048)	(0.054)	(0.053)	(0.004)	(0.027)	(0.030)
2	1	0.5	0.054	0.055	0.058	0.054	0.053	0.054	0.053	0.054	0.053
			(0.057)	(0.058)	(0.059)	(0.054)	(0.054)	(0.054)	(0.054)	(0.051)	(0.053)
		0.9	0.049	0.048	0.050	0.046	0.051	0.050	0.038	0.045	0.047
			(0.050)	(0.047)	(0.050)	(0.047)	(0.049)	(0.051)	(0.039)	(0.042)	(0.046)
	3	0.5	0.049	0.054	0.053	0.046	0.050	0.049	0.039	0.044	0.047
			(0.051)	(0.056)	(0.056)	(0.048)	(0.052)	(0.050)	(0.039)	(0.045)	(0.046)
		0.9	0.035	0.045	0.046	0.019	0.049	0.050	0.000	0.011	0.027
			(0.049)	(0.049)	(0.050)	(0.031)	(0.052)	(0.050)	(0.000)	(0.009)	(0.025)
			AUC=0.8
			λ=0.5			λ=1.0			λ=2.0
			θ	A1	A2	θ	A1	A2	θ	A1	A2
1∕b	t	υ
1	1	0.5	0.056	0.055	0.054	0.052	0.053	0.054	0.051	0.055	0.054
			(0.056)	(0.055)	(0.056)	(0.052)	(0.054)	(0.055)	(0.052)	(0.055)	(0.056)
		0.9	0.046	0.046	0.045	0.046	0.049	0.053	0.049	0.046	0.048
			(0.046)	(0.047)	(0.047)	(0.048)	(0.052)	(0.050)	(0.050)	(0.052)	(0.049)
	3	0.5	0.047	0.049	0.051	0.045	0.050	0.048	0.051	0.056	0.057
			(0.049)	(0.052)	(0.051)	(0.048)	(0.051)	(0.048)	(0.054)	(0.056)	(0.056)
		0.9	0.005	0.028	0.033	0.018	0.042	0.045	0.035	0.047	0.047
			(0.012)	(0.033)	(0.032)	(0.036)	(0.045)	(0.048)	(0.051)	(0.048)	(0.049)
2	1	0.5	0.054	0.053	0.053	0.054	0.055	0.056	0.052	0.054	0.055
			(0.061)	(0.061)	(0.061)	(0.051)	(0.051)	(0.051)	(0.052)	(0.055)	(0.054)
		0.9	0.041	0.043	0.046	0.041	0.047	0.048	0.046	0.051	0.052
			(0.040)	(0.043)	(0.045)	(0.043)	(0.045)	(0.047)	(0.047)	(0.052)	(0.052)
	3	0.5	0.041	0.046	0.046	0.047	0.045	0.047	0.047	0.052	0.054
			(0.039)	(0.041)	(0.040)	(0.046)	(0.048)	(0.048)	(0.049)	(0.052)	(0.050)
		0.9	0.001	0.021	0.033	0.003	0.032	0.036	0.014	0.042	0.048
			(0.001)	(0.016)	(0.027)	(0.006)	(0.036)	(0.043)	(0.017)	(0.046)	(0.044)