st: Re: residuals over years

[Christopher F Baum <baum@bc.edu>]

On Oct 19, 2004, at 2:33, David wrote:

> for each y of local Y {
>       reg  y  x1  x2  x3  if year==`y'
>       predict temp, residual
>       replace residual=temp if year==`y'
>       drop temp
> }
Two issues:

(1) it is usually a good idea to 'predict double' when computing 
residuals unless memory is a real issue.

(2) the 'predict' above is overwhelmingly inefficient (computationally) 
because it will predict over the whole sample. Use 'predict temp if 
e(sample), residual' to avoid this. The replace if-clause can also read 
if e(sample), but that will not matter, since only values computed in 
the predict will be copied.

Kit Baum, Boston College Economics      baum@bc.edu
http://ideas.repec.org/e/pba1.html

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