Table 1

Parameter estimates for the five models which were used to predict the baseline EQ-5D scores.
	Model
	A	B	C	D	E

Intercept	0.900‡	0.886‡	0.747‡	0.691‡	-0.347
total WOMAC	-0.009‡		0.001		-0.001
pain		-0.012		-0.009
stiffness		0.006		0.092†
functioning		-0.009‡		-0.005
pain* stiffness				-0.005
pain*functioning				-0.001
stiffness*functioning				0.001
pain²				0.002
stiffness²				-0.011
functioning²				0.000
total WOMAC²			-0.000‡		-0.000†
age					0.033*
age²					0.000
sex (if Female)					0.048
Range of predicted scores	0.086 to 0.900	0.086 to 0.900	-0.235 to 0.748	-0.111 to 0.852	-0.184 to 0.828
MAE	0.148	0.147	0.140	0.146	0.129
Adjusted r²	0.275	0.274	0.296	0.299	0.313
RMSE	0.189	0.187	0.185	0.190	0.180

* = p < 0.05, † = p < 0.01, ‡ = p < 0.001, MAE = Mean Absolute Error, RMSE = Root Mean Squared Error. See Appendix 1 for full details of Model C and Model E.
Barton et al. Health and Quality of Life Outcomes 2008 6:51 doi:10.1186/1477-7525-6-51