Table II.

Table II. Comparison of precision (repeatability) and accuracy between methods

	Precision (repeatability) (n = 15)			Accuracy (n = 14)
Method*	Repeatability ratio	p-value†		RMSE ratio‡	p-value§
Two-dimensional
MB-RSA versus EGS-RSA	1.27	0.39		0.85	0.10
EGS-RSA versus PolyWare	1.03	0.92		0.38	< 0.001
MB-RSA versus PolyWare	1.35	0.28		0.32	< 0.001
Three-dimensional
MB-RSA versus EGS-RSA	1.02	0.94		1.36	0.10
EGS-RSA versus PolyWare	1.32	0.31		0.42	< 0.01
MB-RSA versus PolyWare	1.29	0.35		0.56	0.04

* EGS-RSA, RSA method featuring analysis of head penetration by computer-generated geometric sphere models; MB-RSA, RSA method featuring analysis of head penetration by reverse engineered (scanned) cup models; PolyWare, method for polyethylene wear analysis in plain radiographs † F-test, associated with the repeatability ratio = 1 ‡ RMSE, root mean square error ratio between methods for linear regression § Pitmans test, associated with the RMSE ratio = 1