Hi! I read a post in this page about how to determine the appropriate linear regression weighting. The natural log of instrument response was plotted against the natural log of standard concentration. The slope of this line was then used to determine whether unweighted linear regression, linear regression using a 1/x weighting factor, or linear regression using a 1/x2 weighting factor would be used, according to the following criteria: slope < 0.25 = unweighted; 0.25 < slope < 0.75 = 1/x weighting factor; slope > 0.75 = 1/x2 weighting factor. I want to use this criteria but I need a reference to use it. In what paper or book can I find this criteria? Thanks!