OLS estimate of beta and usual standard errors 
 
482.553 6222.278 2.196 1.155 
93.603 40.795 0.041 0.045 
 
 
GLS estimate of beta and usual standard errors 
 
609.182 6182.115 2.163 1.235 
46.598 53.211 0.028 0.042 
 
 
Robust sandwich standard errors 
 
38.075 54.095 0.03 0.041