I am trying to store the coefficients of a regression in macros for later use. The following code runs fine until the last line, which returns an error: "_b not found."
Code:


webuse auto, clear reg price mpg rep78 ereturn list local slope_x1 = _b[mpg] display `slope_x1' local slope_x2 = _b[rep78] display `slope_x2' local intercept = _b{_cons]



Many thanks if you can tell me why!



Bonus round: I'm a little unclear on what the _b actually are. They don't seem to be macros. They're called _variables, but I don't see them in the dataset, and variables that are in the dataset can't generally be copied into macros using the local command.



Where do the _b live, and how are they different from macros or variables? Thanks again.