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Re: st: suest and factor coding
From
Tim Wade <[email protected]>
To
[email protected]
Subject
Re: st: suest and factor coding
Date
Fri, 17 Dec 2010 15:43:30 -0500
Michael, thanks. Tim
On Fri, Dec 17, 2010 at 1:53 PM, Michael N. Mitchell
<[email protected]> wrote:
> Dear Tim
>
> Jeff Pitplado of Stata answered this question recently, see
>
> http://www.stata.com/statalist/archive/2010-12/msg00235.html
>
> Best regards,
>
> Michael N. Mitchell
> Data Management Using Stata - http://www.stata.com/bookstore/dmus.html
> A Visual Guide to Stata Graphics - http://www.stata.com/bookstore/vgsg.html
> Stata tidbit of the week - http://www.MichaelNormanMitchell.com
>
>
>
> On 2010-12-17 9.25 AM, Tim Wade wrote:
>>
>> Hi Statalist,
>>
>> I am using Stata V 11.1 SE, Windows XP
>>
>> I have run across an issue with -suest- in Version 11 with the new
>> factor coding. Basically, I get the error "too many base levels
>> specified" when I try to "suest" models that share the same factor
>> variable, but include different values of the factor variable. When I
>> revert to the old "xi" syntax, the models can be combined with -suest-
>> as expected. I can recreate this problem with the following example:
>>
>> sysuse auto.dta
>> xtile pricecat=price, nq(4)
>> logistic foreign trunk headroom i.pricecat if pricecat<=2
>> est store m1
>> logistic foreign trunk headroom mpg i.pricecat if pricecat>2
>> est store m2
>> suest m1 m2
>> *error produced "too many base levels specified"
>> xi: logistic foreign trunk headroom i.pricecat if pricecat<=2
>> est store m3
>> xi: logistic foreign trunk headroom mpg i.pricecat if pricecat>2
>> est store m4
>> suest m3 m4
>> *suest produces following results:
>>
>> Simultaneous results for m3, m4
>>
>> Number of obs =
>> 74
>>
>>
>> ------------------------------------------------------------------------------
>> | Robust
>> | Coef. Std. Err. z P>|z| [95% Conf.
>> Interval]
>>
>> -------------+----------------------------------------------------------------
>> m3_foreign |
>> trunk | -.1917506 .2408272 -0.80 0.426 -.6637633
>> .280262
>> headroom | .1620987 .842212 0.19 0.847 -1.488607
>> 1.812804
>> _Ipricecat_2 | .3446382 .7647411 0.45 0.652 -1.154227
>> 1.843503
>> _Ipricecat_3 | (omitted)
>> _Ipricecat_4 | (omitted)
>> _cons | .2902781 1.124931 0.26 0.796 -1.914546
>> 2.495102
>>
>> -------------+----------------------------------------------------------------
>> m4_foreign |
>> trunk | -.5303469 .2455778 -2.16 0.031 -1.01167
>> -.0490233
>> headroom | .2068252 .7818994 0.26 0.791 -1.325669
>> 1.73932
>> mpg | .1186309 .0674696 1.76 0.079 -.0136071
>> .2508688
>> _Ipricecat_2 | (omitted)
>> _Ipricecat_3 | -.4138492 1.126895 -0.37 0.713 -2.622524
>> 1.794825
>> _Ipricecat_4 | (omitted)
>> _cons | 4.712297 4.920069 0.96 0.338 -4.930861
>> 14.35545
>>
>> ------------------------------------------------------------------------------
>>
>> Anyone have an idea why -suest- cannot combine models with the new
>> factor variable coding? Am I making an error, or cound this be
>> intentional? Otherwise is it a bug?
>>
>> Many thanks. Tim
>> *
>> * For searches and help try:
>> * http://www.stata.com/help.cgi?search
>> * http://www.stata.com/support/statalist/faq
>> * http://www.ats.ucla.edu/stat/stata/
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/