Introduction
Methods
Measures
Statistical analyses
Model 1  OLS 
\(= \beta _{0} + \beta _{1} PANSStotal_{{\text{i}}} + \varepsilon _{i}\)

Tobit 
\(= \beta _{0} + \beta _{1} PANSStotal_{{\text{i}}} + \varepsilon _{i}\)
 
CLAD 
\(={\beta }_{0}+{\beta }_{1}{\text{PANSStotal}}_{\text{i}}+{\varepsilon }_{i}\)
 
Model 2  OLS 
\(= \beta _{0} + \beta _{1} PANSSpositive_{{\text{i}}} + \beta _{2} PANSSnegative_{{\text{i}}} + \beta _{3} PANSSgeneralpsychopathology_{i} + e_{i}\)

Tobit 
\(= \beta _{0} + \beta _{1} PANSSpositive_{{\text{i}}} + \beta _{2} PANSSnegative_{{\text{i}}} + \beta _{3} PANSSgeneralpsychopathology_{i} + e_{i}\)
 
CLAD 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSSgeneralpsychopathology}_{i}+{e}_{i}\)
 
Model 3  OLS 
\(= \beta _{0} + \beta _{1} PANSSpositive_{{\text{i}}} + \beta _{2} PANSSnegative_{i} + \beta _{3} PANSSexcitement_{{\text{i}}}\)
\(+ \beta _{4} PANSSdepression_{{\text{i}}} + \beta _{5} PANSScognitive_{{\text{i}}} + e_{i}\)

Tobit 
\(= \beta _{0} + \beta _{1} PANSSpositive_{{\text{i}}} + \beta _{2} PANSSnegative_{{\text{i}}} + \beta _{3} PANSSexcitement_{{\text{i}}}\)
\(+ \beta _{4} PANSSdepression_{{\text{i}}} + \beta _{5} PANSScognitive_{{\text{i}}} + e_{i}\)
 
CLAD 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSS excitement}_{i}\)
\(+{ \beta }_{4}{PANSS depression}_{i}+{\beta }_{5}{PANSS cognitive}_{i}+{e}_{i}\)
 
Model 4  OLS 
\(={\beta }_{0}+{\beta }_{1}{PANSS total}_{i}+{\beta }_{2}{age}_{i}+{\beta }_{3}{gender}_{i}+{\varepsilon }_{i}\)

Tobit 
\(={\beta }_{0}+{\beta }_{1}{PANSS total}_{i}+{\beta }_{2}{age}_{i}+{\beta }_{3}{gender}_{i}+{\varepsilon }_{i}\)
 
CLAD 
\(={\beta }_{0}+{\beta }_{1}{PANSS total}_{i}+{\beta }_{2}{age}_{i}+{\beta }_{3}{gender}_{i}+{\varepsilon }_{i}\)
 
Model 5  OLS 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSSgeneralpsychopathology}_{i}\)
\(+{ \beta }_{4}{age}_{i}+{\beta }_{5}{gender}_{i}+{\varepsilon }_{i}\)

Tobit 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSSgeneralpsychopathology}_{i}\)
\(+{ \beta }_{4}{age}_{i}+{\beta }_{5}{gender}_{i}+{\varepsilon }_{i}\)
 
CLAD 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSSgeneralpsychopathology}_{i}\)
\(+{ \beta }_{4}{age}_{i}+{\beta }_{5}{gender}_{i}+{\varepsilon }_{i}\)
 
Model 6  OLS 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSS excitement}_{i}\)
\(+{ \beta }_{4}{PANSS depression}_{i}+{\beta }_{5}{PANSS cognitive}_{i}+{ \beta }_{6}{age}_{i}+{\beta }_{7}{gender}_{i}+{\varepsilon }_{i}\)

Tobit 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSS excitement}_{i}\)
\(+{ \beta }_{4}{PANSS depression}_{i}+{\beta }_{5}{PANSS cognitive}_{i}+{ \beta }_{6}{age}_{i}+{\beta }_{7}{gender}_{i}+{\varepsilon }_{i}\)
 
CLAD 
\(={\beta }_{0}+{\beta }_{1}{PANSS positive}_{i}+{\beta }_{2}{PANSS negative}_{i}+{\beta }_{3}{PANSS excitement}_{i}\)
\(+{ \beta }_{4}{PANSS depression}_{i}+{\beta }_{5}{PANSS cognitive}_{i}+{ \beta }_{6}{age}_{i}+{\beta }_{7}{gender}_{i}+{\varepsilon }_{i}\)

Results
Descriptive statistics
N (%)  

Age, mean (SD)  39.70 (10.28) 
Gender  
Female  105 (43.9) 
Male  134 (56.1) 
Ethnicity  
Chinese  143 (59.8) 
Malay  46 (19.3) 
Indian  44 (18.4) 
Others  6 (2.5) 
Education  
Primary and below  25 (10.4) 
Secondary  91 (30.1) 
Post secondary to PreUniversity  86 (36.0) 
University  37 (15.5) 
Marital status  
Never married  180 (75.3) 
Currently married  31 (13.0) 
Separated  9 (3.8) 
Divorced  17 (7.1) 
Widowed  2 (0.8) 
Mapping on EQ5D5L
EQ5D5L  SF6D  

OLS  CLAD  Tobit  OLS  CLAD  Tobit  
Model specification  
Model 1  
PANSS total  − 0.0078*  − 0.0076*  − 0.0105*  − 0.0044*  − 0.0038*  − 0.0045* 
Goodnessoffit indices  
R^{2}  0.2890  0.2890  0.2890  0.2072  0.2072  0.2072 
Adjusted R^{2}  0.2860  0.2860  0.2860  0.2039  0.2039  0.2039 
MSE  0.0353  0.0371  0.0427  0.0177  0.0179  0.0177 
MAE  0.1425  0.1382  0.1542  0.1102  0.1100  0.1105 
Model 2  
Positive  − 0.0043  − 0.0037  − 0.0066  − 0.0026  − 0.0014  − 0.0027 
Negative  0.0023  0.0053  0.0030  0.00004  − 0.0001  0.00001 
General psychopathology  − 0.0146*  − 0.0169*  − 0.0191*  − 0.0076*  0.0079*  − 0.0078* 
Goodnessoffit indices  
R^{2}  0.3327  0.3220  0.3325  0.2263  0.2200  0.2263 
Adjusted R^{2}  0.3242  0.3134  0.3240  0.2164  0.2100  0.2164 
MSE  0.0334  0.0358  0.0408  0.0174  0.0180  0.0174 
MAE  0.1359  0.1312  0.1481  0.2000  0.1095  0.1107 
Model 3  
Positive  − 0.0100*  − 0.0100*  − 0.0140*  − 0.0057*  − 0.0042  − 0.0058* 
Negative  − 0.0119*  − 0.0045  − 0.0165*  − 0.0076*  − 0.0084*  − 0.0077* 
Excitement  − 0.0038  − 0.0083  − 0.0035  − 0.0050  − 0.0014  − 0.0054 
Depression  − 0.0223*  − 0.0247*  − 0.0322*  − 0.0149*  − 0.0137*  − 0.0153* 
Cognitive  − 0.0023  0.0008  0.0052  − 0.0100  − 0.0094  0.0103 
Goodnessoffit indices  
R^{2}  0.3244  0.3054  0.3295  0.2869  0.2564  0.2869 
Adjusted R^{2}  0.3099  0.2905  0.3151  0.2716  0.2405  0.2716 
MSE  0.0338  0.0371  0.0420  0.0162  0.0170  0.0162 
MAE  0.1388  0.1306  0.1540  0.1056  0.1069  0.1059 
Model 4  
PANSS total  − 0.0160*  − 0.0064*  − 0.0105*  − 0.0088*  − 0.0042*  − 0.0045* 
Age  − 0.0029*  − 0.0034*  − 0.0045*  − 0.0005  − 0.0019  − 0.0004 
Gender  0.0091  0.0295  0.0289  0.0012  0.0128  0.0029 
Goodnessoffit indices  
R^{2}  0.3430  0.3015  0.3064  0.2230  0.1662  0.2085 
Adjusted R^{2}  0.3346  0.2926  0.2975  0.2130  0.1556  0.1984 
MSE  0.0329  0.0374  0.0426  0.0175  0.0190  0.0178 
MAE  0.1359  0.1377  0.1579  0.1107  0.1105  0.1111 
Model 5  
Positive  − 0.0044  − 0.0071*  − 0.0070  − 0.0026  − 0.0027  − 0.0027 
Negative  0.0025  0.0062*  0.0033  − 0.00005  − 0.0005  0.0001 
General psychopathology  − 0.0146*  − 0.125*  − 0.0189*  − 0.0075*  − 0.0072*  − 0.0077* 
Age  − 0.0029*  − 0.0024*  − 0.0045*  − 0.0005  − 0.0014  − 0.0004 
Gender  0.0149  0.0332  0.0338  0.0031  0.0109  0.0041 
Goodnessoffit indices  
R^{2}  0.3519  0.2922  0.3509  0.2278  0.2083  0.2277 
Adjusted R^{2}  0.3380  0.2770  0.3370  0.2112  0.1913  0.2111 
MSE  0.0328  0.0385  0.0406  0.0175  0.0192  0.0175 
MAE  0.1348  0.1322  0.1513  0.1109  0.1146  0.1112 
Model 6  
Positive  − 0.0096*  − 0.0105*  − 0.0137*  − 0.0056*  − 0.0054*  − 0.0057* 
Negative  − 0.0122*  − 0.0051  − 0.0170*  − 0.0078*  − 0.0092*  − 0.0079* 
Excitement  − 0.0045  − 0.0084  − 0.0045  − 0.0052  − 0.0026  − 0.0055 
Depression  − 0.0227*  − 0.0230*  − 0.0323*  − 0.0152*  − 0.0138*  − 0.0155* 
Cognitive  − 0.0018  0.0018  0.0064  − 0.0102  0.0111  0.0105 
Age  − 0.0032*  − 0.0013  − 0.0050*  − 0.0008  − 0.0016  − 0.0007 
Gender  0.0082  − 0.0038  0.0220  0.0033  0.0093  0.0025 
Goodnessoffit indices  
R^{2}  0.3539  0.3008  0.3512  0.2900  0.2639  0.2899 
Adjusted R^{2}  0.3343  0.2780  0.3315  0.2685  0.2416  0.2684 
MSE  0.0329  0.0376  0.0417  0.0162  0.0170  0.0162 
MAE  0.1372  0.1369  0.1581  0.1058  0.1048  0.1061 
EQ5D5L  SF6D  

Mean  SD  Mean  SD  
Observed EQ5D5L utility scores  0.8117  0.2225  0.6836  0.1490 
Predicted EQ5D5L utility scores  
OLS  
Model 1  0.8117  0.1196  0.6836  0.0678 
Model 2  0.8117  0.1283  0.6836  0.0709 
Model 3  0.8117  0.1281  0.6836  0.0798 
Model 4  0.8117  0.1303  0.6836  0.0704 
Model 5  0.8117  0.1320  0.6836  0.0711 
Model 6  0.8117  0.1323  0.6836  0.0802 
CLAD  
Model 1  0.8514  0.1364  0.6713  0.0745 
Model 2  0.8474  0.1428  0.6633  0.0665 
Model 3  0.8417  0.1502  0.6806  0.0622 
Model 4  0.8372  0.1027  0.6671  0.0589 
Model 5  0.8492  0.1253  0.6972  0.1001 
Model 6  0.8667  0.1131  0.6708  0.0745 
Tobit  
Model 1  0.8858  0.1626  0.6858  0.0696 
Model 2  0.8843  0.1724  0.6858  0.0728 
Model 3  0.8860  0.1769  0.6857  0.0817 
Model 4  0.8860  0.1702  0.6858  0.0697 
Model 5  0.8844  0.1795  0.6858  0.0729 
Model 6  0.8862  0.1851  0.6857  0.0820 