FIT OF BIEXPONENTIAL DATA BY IRWLS USING SELF-STARTING METHOD 
 
Start value =  2.608519 2.743073 0.309329 0.310255 
and # obs used in 2nd phase =  6 
 
Fit of model with power 1 
 
Estimate of beta 2.167492 2.295136 0.268992 0.285295 
Number of iterations 7 
Estimate of sigma squared 0.021122 
Estimate of sigma 0.145333