Table 3 Coefficient estimates and goodness-of-fit measures of various regression models mapping the FACT-B subscales to EQ-5D-5L utility index based on baseline survey (N = 238)

Ordinary least square

Regression coefficients

 Constant

0.2901^**

0.3071^**

0.3064^**

0.2846^**

0.3031^**

 Physical well-being

0.0120^**

0.0127^**

0.0125^**

0.0121^**

0.0128^**

 Social well-being

−0.0003

−0.0003

 Emotional well-being

0.0042^*

0.0062^**

0.0041

0.0061^**

 Functional well-being

0.0046^**

0.0048^**

0.0052^**

0.0044^**

0.0046^**

 Breast cancer subscale

0.0035^*

0.0048^**

0.0034^*

Goodness-of-fit measures

 Square of correlation coefficient, r²

0.4975

0.4870

0.4890

0.4973

0.4870

 Adjusted r²

0.4867

0.4782

0.4824

0.4887

0.4804

 Mean square error

0.0132

0.0135

0.0135

0.0132

0.0135

 Mean absolute deviation

0.0913

0.0918

0.0925

0.0913

0.0919

Tobit model

Regression coefficients

 Constant

0.1983^**

0.2200^**

0.2342^**

0.2077^**

0.2318^**

 Physical well-being

0.0144^**

0.0153^**

0.0147^**

0.0142^**

0.0152^**

 Social well-being

0.0006

0.0007

 Emotional well-being

0.0050

0.0077^**

0.0051

0.0078^**

 Functional well-being

0.0048^*

0.0051^**

0.0060^**

0.0051^**

0.0054^**

 Breast cancer subscale

0.0045^*

0.0063^**

0.0046^*

Goodness-of-fit measures

 Square of correlation coefficient, r²

0.4965

0.4861

0.4887

0.4971

0.4869

 Adjusted r²

0.4856

0.4773

0.4821

0.4885

0.4803

 Mean square error

0.0143

0.0146

0.0145

0.0143

0.0145

 Mean absolute deviation

0.0934

0.0937

0.0945

0.0934

0.0936

Censored least absolute deviation

Regression coefficients

 Constant

0.3062^**

0.3208^**

0.3200^**

0.2948^**

0.3149^**

 Physical well-being

0.0119^**

0.0121^**

0.0123^**

0.0122^**

0.0121^**

 Social well-being

−0.0004

−0.0003

 Emotional well-being

0.0041

0.0054^**

0.0042

0.0054^**

 Functional well-being

0.0037^*

0.0054^**

0.0039^*

0.0037^*

0.0053^**

 Breast cancer subscale

0.0036

0.0054^**

0.0035

Goodness-of-fit measures

 Square of correlation coefficient, r²

0.4968

0.4863

0.4873

0.4968

0.4862

 Adjusted r²

0.4860

0.4775

0.4807

0.4882

0.4796

 Mean square error

0.0133

0.0135

0.0135

0.0133

0.0135

 Mean absolute deviation

0.0912

0.0917

0.0923

0.0913

0.0917

Model 1

Model 2

Model 3

Model 4

Model 5

Quantile regression

Regression coefficients

 Constant

0.3062^**

0.3208^**

0.3200^**

0.2948^**

0.3149^**

 Physical well-being

0.0119^**

0.0121^**

0.0123^**

0.0122^**

0.0121^**

 Social well-being

−0.0004

−0.0003

 Emotional well-being

0.0041

0.0054^**

0.0042^*

0.0054^**

 Functional well-being

0.0037^**

0.0054^**

0.0039^**

0.0037^**

0.0053^**

 Breast cancer subscale

0.0036

0.0054^**

0.0035

Goodness-of-fit measures

 Square of correlation coefficient, r²

0.4968

0.4863

0.4873

0.4968

0.4862

 Adjusted r²

0.4860

0.4775

0.4807

0.4882

0.4796

 Mean square error

0.0133

0.0135

0.0135

0.0133

0.0135

 Mean absolute deviation

0.0912

0.0917

0.0923

0.0913

0.0917

Logistic quantile regression

Regression coefficients

 Constant

−1.6525

−1.6097

−1.5750^*

−1.6489

−1.6678

 Physical well-being

0.0684

0.0710

0.0678^*

0.0683^**

0.0722^**

 Social well-being

0.0001

−0.0035

 Emotional well-being

0.0155

0.0320

0.0157

0.0308

 Functional well-being

0.0230

0.0312

0.0247

0.0230

0.0295

 Breast cancer subscale

0.0216

0.0301

0.0214

Goodness-of-fit measures

 Square of correlation coefficient, r²

0.4686

0.4596

0.4620

0.4687

0.4597

 Adjusted r²

0.4571

0.4503

0.4551

0.4596

0.4528

 Mean square error

0.0141

0.0143

0.0143

0.0141

0.0143

 Mean absolute deviation

0.0946

0.0949

0.0953

0.0946

0.0950