Table 6.

McNemar Chi Squared Test Measuring Statistical Significance

McNemar Chi Squared Test (with 1 Degree of Freedom) with Likelihood [confidence interval (CI, %)] that Modified Absolute Gradient count (Equation 21) is statistically different from other focus functions with regard to accurate location of tissue surfaces.
Eq.	Function	Training		Test Set1		Test Set2		Thickness Test Set
Eq.	Function	X²	CI	X²	CI	X²	CI	X²	CI
(3)	Absolute Gradient	0.25	38	NSD^*	0	NSD^*	0	0.25	38
(4)	Squared Gradient	0.13	28	0.56	55	6.04	99	2.52	23
(5)	Brenner Gradient	0.25	38	0.56	55	NSD^*	0	0.06	20
(20)	Modified Absolute Gradient	NSD^*	0	0.28	40	0.25	38	2.08	85
(22)	Filtered Modified Absolute Gradient	NSD^*	0	0.28	40	0.25	38	0.08	23
(23)	Filtered Modified Absolute Gradient Count	NSD^*	0	NSD^*	0	0.25	38	0.13	28
(6)	Content	22.23	100	24.01	100
(8)	Image Power	25.01	100	24.01	100
(7)	Pixel Count	25.01	100	19.01	100
(9)	Tenenbaum Gradient	1.23	73	8.03	100
(10)	Energy Laplace	0.56	55	1.13	71	19.01	100	8.22	100
(11)	Variance	13.35	100	22.01	100
(12)	Normal Variance	17.28	100	22.01	100
(13)	Autocorrelation	0.28	40	4.69	97
(14)	St Dev Autocorrelation	23.22	100	24.01	100
(15)	Range	14.33	100	22.01	100
(16)	Entropy	15.31	100	20.01	100

NSD = No statistical difference