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Re: st: Predict Command


From   Jhilbe@aol.com
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Predict Command
Date   Tue, 8 Mar 2005 14:40:23 EST

If you re-run the poisson model  using only predictors that appeared 
significant in the larger model, you may  find that the previously significant 
predictors are now not all significant. You  must check. Simply rerun the model using 
only those predictors that were  significant and check to see if that still 
remain the case. If it does, then  type -predict mu, mu- to get the predicted 
counts, if that is what you want.  However, I myself double check predictors, 
especially ones that have p-values  close to .05, with the likelihood ratio 
test. The latter test is more reliable  than Z-, t-, or Wald tests. 

Joe  Hilbe
=========================================================
Hi  All

I have a question on predict command. 

If I run a poisson  regression such as

poisson absdays male black hispanic  bluecollarworkers
nohealthinsurance backpain comorbidconditions

where  all the independent variables are dummy
variables. 

absdays=constant +  b1*male + b2*black + b3*hispanic +
b4*bluecollarworkers +  b5*nohealthinsurance +
b6*backpain + b7*comorbidconditions 

If from  the output only black, backpain, and
comorbidconditions were statistically  significant, can
I run the predict command to obtain
the predicted number  of absdays using only the
significant variables?

In otherwords can I  get the predicted absdays as

constant + b2*black + b6*backpain  +
b7*comorbidconditions 

I know one option is to use the generate  command but I
would like to know if we can do this using predict
command  too. 

Thank you for your  time.

Regards
Anju

____________________________________________________________

Anju  Parthan, 
Doctoral Candidate, 
The University of Texas at Austin,  PHAR-PHARMACY ADMIN 
1 UNIVERSITY STATION A 1930, AUSTIN, TX-78712 
Tel:  (512) 459-4942; Fax: (512) 471-8762






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