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Table 2 Parameter estimates from the 5 class mixture model

From: Modelling the relationship between the WOMAC osteoarthritis index and EQ-5D

   Class 1 Class 2 Class 3 Class 4 Class 5
Parameter p-value p-value p-value p-value p-value
Within class Pain/10 0.0166 0.260   −0.2357 0.000 *** 0.1475 0.000 *** 0.001 0.285   0.0116 0.600  
Stiffness/10 0.0118 0.583   −0.0287 0.760   −0.0182 0.662   −0.0029 0.057 * 0.0037 0.914  
Function/10 −0.0356 0.000 *** −0.0274 0.103   −0.07 0.000 *** −0.0003 0.087 * −0.0403 0.000 ***
Variance 0.0024 0.000 *** 0.0406 0.000 *** 0.0047 0.001 *** 0 0.000 *** 0.0058 0.002 ***
Random effects terms Intercept 0.7636 0.000 *** 0.3762 0.000 *** 0.9662 0.000 *** 0.555 0.000 *** 0.2118 0.000 ***
Age1 0.005 0.000 ***             
Male 0.0083 0.000 ***             
Variance 0.0016 0.000 ***             
Class probabilities Intercept 8.8821 0.000 *** 7.0881 0.000 *** 11.4076 0.000 *** 5.1497 0.0004 ***    
Pain/10 −5.1772 0.006 *** −7.9363 0.000 *** −13.4885 0.000 *** −6.4654 0.0006 ***    
Stiffness/10 −1.0227 0.625   −6.1566 0.004 *** −0.7275 0.751   −1.0918 0.6023     
Function/10 −1.3706 0.026 ** −0.9434 0.162   −2.0612 0.002 *** 0.37 0.5729     
(Pain/10)2 1.2266 0.114   2.3464 0.001 *** 4.5149 0.000 *** 1.4951 0.0568 *    
(Stiffness/10)2 −1.158 0.604   3.7049 0.156   −1.483 0.570   −1.3521 0.5465     
(Function/10)2 0.0797 0.286   0.1946 0.008 *** 0.2545 0.001 *** −0.0626 0.4179     
EQ-5D estimates by class Mean 0.678    0.124    0.881    0.557    0.106   
Median 0.679    0.129    0.865    0.557    0.107   
Min 0.307    −0.594    0.335    0.382    −0.377   
Max 1    1    1    0.748    0.598   
Proportion of ones 0.004    0.001    0.431    0.000    0.000   
Prob of class membership 0.333    0.109    0.240    0.146    0.172   
  1. Notes: 1Age = (age-mean age in sample)/10. Mean sample age is 69 years.
  2. *: P<0.1, **: P<0.05, ***: P<0.01.