Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: Subpop - losing observations - a similar problem


From   j.fagg@qmul.ac.uk
To   statalist@hsphsun2.harvard.edu
Subject   st: Subpop - losing observations - a similar problem
Date   Mon, 10 Sep 2007 21:39:57 +0100

Dear Statalisters,

I am trying to select a subpopulation for use with svy: mlogit.

The variable which specifies the subpopulation has 1130 observations  
with a value of 1, 1792 0s and no missing data. However, when I run  
the syntax (below), only 1099 observations are included in the analysis

xi: svy, subpop(varname): x y1 y2, rrr

Searching on the archives here brought me to a post about 'losing  
observations'

"From   Suzy <scott_788@wowway.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Why does one command "lose" observations compared to  
another command?
Date   Sun, 22 Jan 2006 11:56:50 -0500 "

This problem seemed similar to the one I have and the answers  
suggested that it might be something to do with a weights variable  
having zeros on it.

I have checked my probability weight variable which is invoked earlier  
in the syntax by svyset, and it contains 121 0s, which doesn't quite  
explain the 131 missing observations.

When I specify the brr option to include both the probability weight  
and bootstrap weights (see below), all 1130 observations ARE included  
in the analysis

xi: svy brr, subpop(varname): x y1 y2, rrr

I would really appreciate any help.

Thanks,

Jamie




*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index