Dear Rich,
Thanks a lot for taking your time to help out. This is certainly very
good to know.
I also noticed that -xtreg, fe- does not have the same problem as
-areg-, i.e. with -xtreg, fe-, the same collinear variable drops out.
Does -xtreg, fe- use a different precision?
Thanks again,
-Radu
2006/2/28, Richard Gates <[email protected]>:
> In response to Radu's <[email protected]> query on why -areg- was not dropping
> collinear variables, Scott <[email protected]> made an interesting
> demonstration on how machine precision can affect whether -_rmcoll- drops
> variables:
>
> > You replicate this with the grunfeld dataset and the mvalue variable.
...
>
> I would like to add to this demonstration where I show the
> dangers of having single precision variables (float) and not
> promoting them to double precision with caution.
>
> Note that single precision will have only about 7 digits
> of precision while double has about 16 corresponding to
> 24 and 53 bits for the mantissia:
>
...
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