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st: suest and factor coding
From
Tim Wade <[email protected]>
To
[email protected]
Subject
st: suest and factor coding
Date
Fri, 17 Dec 2010 12:25:38 -0500
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
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