Mapping the EQ-5D index from the cystic fibrosis questionnaire-revised using multiple modelling approaches

Table 5 Out-of sample Cross validation of best fitting models - summary of observed and predicted values

	EQ-5D	OLS model 3	OLS model 5	Tobit model 3	Tobit model 5	TPM model 3	TPM model 5
Sample 1
N	97	97	97	97	97	97	97
Mean (SD)	0.6776 (0.277)	0.6755 (0.205)	0.6976 (0.252)	0.6717 (0.207)	0.6891 (0.238)	0.6932 (0.214)	0.6811 (0.270)
Range	−0.3490 - 1	0.2702 - 1.028	0.1038 - 1.269	0.2539 - 0.9729	0.1444 - 1	0.1814 - 0.9734	0.0133, 1
RMSE		0.141	0.163	0.160	0.160	0.187	0.187
ICC		0.65	0.54	0.65	0.53	0.64	0.40
Sample 2
N	101	101	101	101	101	101	101
Mean (SD)	0.6632 (0.288)	0.6701 (0.243)	0.6744 (0.297)	0.6683 (0.246)	0.6744 (0.297)	0.6868 (0.263)	0.6785 (0.329)
Range	−0.1810 - 1	−0.0399 - 1.006	−0.1850 - 1.242	−0.0040 - 0.981	−0.2001 - 1	−0.1830 - 0.9838	−0.1642, 1
RMSE		0.118	0.165	0.162	0.162	0.182	0.182
ICC		0.79	0.61	0.79	0.64	0.79	0.50
Sample 3
N	100	100	100	100	100	100	98
Mean (SD)	0.6742 (0.277)	0.6696 (0.202)	0.6791 (0.221)	0.6779 (0.210)	0.6808 (0.236)	0.6954 (0.214)	0.6886 (0.252)
Range	−0.1810 - 1	0.2417 - 0.9782	0.0777 - 1.193	0.2592 - 0.9824	−0.0555 - 1	0.2593 - 0.9837	0.1442, 1
RMSE		0.146	0.196	0.204	0.204	0.223	0.223
ICC		0.50	0.31	0.52	0.29	0.49	0.29
Sample 4
N	103	103	103	103	103	103	103
Mean (SD)	0.6688 (0.287)	0.6703 (0.238)	0.6515 (0.281)	0.6703 (0.237)	0.6526 (0.302)	0.6887 (0.248)	0.6678 (0.295)
Range	−0.3310 - 1	−0.0577 - 1.048	−0.2275 - 1.201	−0.0441 - 0.9839	−0.2964 - 1	−0.1583 - 0.9879	−0.1745, 1
RMSE		0.120	0.185	0.180	0.180	0.207	0.207
ICC		0.80	0.51	0.81	0.56	0.81	0.47

OLS, ordinary least squares; TPM, two-part model; SD, standard deviation; ICC, Intraclass correlation; RMSE, root of the mean square error.
Model 3 = CFQ-R domains that are statistically significant at the 10% level + statistically significant squared terms; Model 5 = All CFQ-R items excluding the health domain items; TPM Model 8 = All CFQ-R items excluding the health domain items + age and gender.

ISSN: 1477-7525