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Re: st: Predict Command after zinb


From   anju parthan <aparthan@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Predict Command after zinb
Date   Sat, 12 Mar 2005 08:29:51 -0800 (PST)

Thanks May and Yulia. 

It works:) 

Regards
Anju
--- May Boggess <mboggess@stata.com> wrote:
> On Friday, Anju asked:
> > 
> > I am trying to understand how the predict command
> > works after zinb command. I want to know if we can
> use
> > generate command to get the same result as predict
> > command. 
> > 
> 
> Here is an example that shows what -predict- can do
> after -zinb-:
> 
>  clear
>  webuse fish
>  drop xb
>  zinb count persons livebait, inf(child camper)
> nolog
>  predict xb1,xb 
>  gen myxb1=[count]_b[persons]*persons /*
>  */ +[count]_b[livebait]*livebait+[count]_b[_cons]
>  sum xb1 myxb1
>  
>  predict xb2,xb equation(#2)
>  gen myxb2=[inflate]_b[child]*child /*
>   */ +[inflate]_b[camper]*camper+ [inflate]_b[_cons]
>  sum xb2 myxb2
> 
>  predict p,p
>  gen myp=exp(xb2)/(1+exp(xb2))
>  sum p myp
> 
>  predict n, n
>  gen myn=(1-p)*exp(xb1)
>  sum n myn
> 
> My technique for finding out what -predict- is up to
> behinds the scenes
> is to use -set trace on-. Now, a lot of times -set
> trace on- produces
> too much output to search through, but I have found
> that for the
> purposes of finding a -predict- formula, there is
> surprisingly little
> output. Then one can look back through the trace to
> find the generate
> statements that -predict- actually used.
> 
> By the way, a nice feature of -set trace on- that I
> have used, is the
> highlight. It highlights a specific word in the
> output making it easier
> to find what you are looking for. Type
> 
>  whelp trace
> 
> to see the help file for that.
> 
> -- May
> mboggess@stata.com
> 
> 
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> *  
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> *   http://www.ats.ucla.edu/stat/stata/
> 

____________________________________________________________
 
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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