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Re: st: Order of variables in stcox model
From
Brigham Whitman <[email protected]>
To
[email protected]
Subject
Re: st: Order of variables in stcox model
Date
Mon, 15 Aug 2011 10:51:21 -0400
Hmm, OK. Thank you for the advice. The comment about
multicolinearity: I have already checked the Pearson's correlation
with "pwcorr" and none of the variables have a correlation above .7.
When I run the model, however, a lot of the variables are dropped for
whatever reason, and I just get a period (".") instead. Thank you for
the help.
-Brigham
On Mon, Aug 15, 2011 at 3:13 AM, Maarten Buis <[email protected]> wrote:
> --- On Aug 12, 2011, at 12:51 PM, Brigham Whitman wrote:
>> My question is: How should I order the variables that I put in the
>> model? I get different results depending on how the variables are
>> ordered. For example:
>>
>> xi: stcox velocity roads snow i.season, nohr strata(sex age) robust
>>
>> will produce different results than:
>>
>> xi: stcox roads snow velocity i.season, nohr strata(sex age) robust
>
> One reason I can think of is when one or more values are dropped due
> to multicolinearity. In that case Stata will have no information it
> can use to determine which variable to drop other than the order in
> which they are entered.
>
> Hope this helps,
> Maarten
>
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
>
>
> http://www.maartenbuis.nl
> --------------------------
>
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