FIT OF THE ASSAY DATA BY GLS 
WITH POWER VARIANCE, THETA UNKNOWN AND ESTIMATED BY
     LOG 
 
 
OLS estimate  482.553 6222.278 2.195828 1.155375 
 
Estimate of assumed constant SD of y  100.7284 
 
 
Iteration  1 
Estimate of theta  0.3185 
 
Iteration  1 
GLS estimate of beta  563.5057 6200.227 2.172132 1.200681 
 
Iteration  2 
Estimate of theta  0.6525 
 
Iteration  2 
GLS estimate of beta  605.068 6183.708 2.163914 1.231633 
 
Iteration  3 
Estimate of theta  0.8162 
 
Iteration  3 
GLS estimate of beta  615.2808 6178.974 2.162585 1.240527 
 
Iteration  4 
Estimate of theta  0.8157 
 
Iteration  4 
GLS estimate of beta  615.293 6179.114 2.162488 1.240486 
 
Iteration  5 
Estimate of theta  0.8155 
 
Iteration  5 
GLS estimate of beta  615.2863 6179.116 2.16249 1.240481 
 
Iteration  6 
Estimate of theta  0.8155 
 
Iteration  6 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  7 
Estimate of theta  0.8155 
 
Iteration  7 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  8 
Estimate of theta  0.8155 
 
Iteration  8 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  9 
Estimate of theta  0.8155 
 
Iteration  9 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  10 
Estimate of theta  0.8155 
 
Iteration  10 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  11 
Estimate of theta  0.8155 
 
Iteration  11 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  12 
Estimate of theta  0.8155 
 
Iteration  12 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  13 
Estimate of theta  0.8155 
 
Iteration  13 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  14 
Estimate of theta  0.8155 
 
Iteration  14 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  15 
Estimate of theta  0.8155 
 
Iteration  15 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  16 
Estimate of theta  0.8155 
 
Iteration  16 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  17 
Estimate of theta  0.8155 
 
Iteration  17 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  18 
Estimate of theta  0.8155 
 
Iteration  18 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  19 
Estimate of theta  0.8155 
 
Iteration  19 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Iteration  20 
Estimate of theta  0.8155 
 
Iteration  20 
GLS estimate of beta  615.2869 6179.115 2.16249 1.240482 
 
Final estimate of sigma  0.12933 
 
Final estimate of theta  0.815488 
 

Formula: ywt ~ weightfunc(x, b1, b2, b3, b4, wt)

Parameters:
    Estimate Std. Error t value Pr(>|t|)    
b1 6.153e+02  4.341e+01   14.17 2.43e-15 ***
b2 6.179e+03  5.682e+01  108.75  < 2e-16 ***
b3 2.162e+00  2.839e-02   76.18  < 2e-16 ***
b4 1.240e+00  4.267e-02   29.07  < 2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 0.1293 on 32 degrees of freedom

Number of iterations to convergence: 6 
Achieved convergence tolerance: 3.866e-06