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st: lincom


From   anju parthan <aparthan@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: lincom
Date   Sat, 19 Mar 2005 12:11:18 -0800 (PST)

Hi All

I am using survey data so I ran ZIP using the
following commands

y = x1 x2 x3 x2*x3 [iweight=perwt00f ],inflate(x1 x2
x3 x2*x3) score(zip*)
suest ., svy

Now I want to test if x2 + x2*x3=0.  

I used the following command

lincom x2 + x2*x3

But I get the following error message

matrix has missing values
r(504);

Am I missing something trivial here?

I also tried using the test command

test x2 = - x2*x3
Adjusted Wald test

( 1)  [y]x2 + [y]x2*x3 = 0

       F(  1,   156) =    8.24
            Prob > F =    0.0047

Since I am using survey data I included nosvyadjust
too.

test x2 = - x2*x3, nosvyadjust

Unadjusted Wald test

 ( 1)  [y]x2 + [y]x2*x3 = 0

       F(  1,   156) =    8.24
            Prob > F =    0.0047


Is the test command doing what lincom would have done?
Can I use the results from test command to test  if x2
+ x2*x3=0?

I would really appreciate if some can help me with
this. 


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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