Statalist


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

st: Testing two cell proportions using tab


From   "Waldo, Daniel R. (CMS/ORDI)" <Daniel.Waldo@cms.hhs.gov>
To   statalist@hsphsun2.harvard.edu
Subject   st: Testing two cell proportions using tab
Date   Tue, 29 Apr 2008 14:47:02 -0400

I am perplexed by the results of some tabulations I ran in Stata SE/10.
Specifically, I am testing for the equality of two cells ... almost
identical to the situation described at
http://www.stata.com/statalist/archive/2005-02/msg00554.html

The commands
svy: tab x1 x2 , row
svy: tab x1 x2 , row se

produce different variance-covariance matrices in e(V). The overall
Pearson results appear identical.

So, when I issue the command
test _b[p11]=_b[p71]

the first command produces results that I believe to be simply wrong -
visual inspection of the two cell values being tested overwhelming
suggests no statistically significant difference yet the F value
produced is huge. The second command produces a very small F value.

Having thought that the se option was merely for display purposes, I
would appreciate any thoughts on these results, or on better ways to
accomplish my task.

Thanks!


*
*   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