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Re: st: factor variables and qreg?


From   Maarten Buis <maartenlbuis@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: factor variables and qreg?
Date   Thu, 23 Aug 2012 10:56:01 +0200

On Wed, Aug 22, 2012 at 11:39 PM, Ariel Linden. DrPH wrote:
> Does anyone know if there is a reason why -qreg- does not allow factor
> variables using the new format available since v11.0?
>
> It does allow for the older approach using the prefix -xi- , which seems a
> bit strange to me. Perhaps this is an oversight by the Stata programmers?

The only authoritative comments can come from StataCorp, but it can be
fun to speculate. I suspect that this is not an oversight.  Many
models are estimated using the common machinery of -ml-, and they
could get most of the work done by changing -ml-. -qreg- seems to have
its own build-in maximization algorithm, which does not surprise me as
it is a maximization problem with its own peculiar set of
difficulties. So it is a lot more work to implement it. It may be that
they are were working on a more general overhaul of -qreg- and did not
get that ready for the Stata 12 release, and thus decided to keep
-qreg- as it is for now. Alternatively, it may just have been lower on
their list of priorities.

-- Maarten

---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany

http://www.maartenbuis.nl
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