FIT OF THE ASSAY DATA BY GLS 
WITH POWER VARIANCE, THETA UNKNOWN AND ESTIMATED BY
     IDENTITY 
 
 
OLS estimate  482.553 6222.278 2.195828 1.155375 
 
Estimate of assumed constant SD of y  100.7284 
 
 
Iteration  1 
Estimate of theta  0.3872 
 
Iteration  1 
GLS estimate of beta  574.9707 6196.145 2.169468 1.20847 
 
Iteration  2 
Estimate of theta  0.6567 
 
Iteration  2 
GLS estimate of beta  605.4155 6183.625 2.163816 1.231912 
 
Iteration  3 
Estimate of theta  0.726 
 
Iteration  3 
GLS estimate of beta  610.3704 6181.482 2.163051 1.236117 
 
Iteration  4 
Estimate of theta  0.7356 
 
Iteration  4 
GLS estimate of beta  610.9831 6181.234 2.162947 1.236638 
 
Iteration  5 
Estimate of theta  0.7367 
 
Iteration  5 
GLS estimate of beta  611.0536 6181.206 2.162935 1.236698 
 
Iteration  6 
Estimate of theta  0.7368 
 
Iteration  6 
GLS estimate of beta  611.0617 6181.203 2.162934 1.236705 
 
Iteration  7 
Estimate of theta  0.7368 
 
Iteration  7 
GLS estimate of beta  611.0627 6181.203 2.162933 1.236706 
 
Iteration  8 
Estimate of theta  0.7368 
 
Iteration  8 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  9 
Estimate of theta  0.7368 
 
Iteration  9 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  10 
Estimate of theta  0.7368 
 
Iteration  10 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  11 
Estimate of theta  0.7368 
 
Iteration  11 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  12 
Estimate of theta  0.7368 
 
Iteration  12 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  13 
Estimate of theta  0.7368 
 
Iteration  13 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  14 
Estimate of theta  0.7368 
 
Iteration  14 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  15 
Estimate of theta  0.7368 
 
Iteration  15 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  16 
Estimate of theta  0.7368 
 
Iteration  16 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  17 
Estimate of theta  0.7368 
 
Iteration  17 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  18 
Estimate of theta  0.7368 
 
Iteration  18 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  19 
Estimate of theta  0.7368 
 
Iteration  19 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Iteration  20 
Estimate of theta  0.7368 
 
Iteration  20 
GLS estimate of beta  611.0628 6181.203 2.162933 1.236706 
 
Final estimate of sigma  0.242128 
 
Final estimate of theta  0.736818 
 

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

Parameters:
    Estimate Std. Error t value Pr(>|t|)    
b1 6.111e+02  4.566e+01   13.38 1.17e-14 ***
b2 6.181e+03  5.412e+01  114.22  < 2e-16 ***
b3 2.163e+00  2.815e-02   76.83  < 2e-16 ***
b4 1.237e+00  4.241e-02   29.16  < 2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 0.2421 on 32 degrees of freedom

Number of iterations to convergence: 6 
Achieved convergence tolerance: 5.45e-06