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Re: st: trend in ORs across ordered levels of a 3rd variable


From   "Joseph Coveney" <jcoveney@bigplanet.com>
To   "Statalist" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: trend in ORs across ordered levels of a 3rd variable
Date   Sat, 19 Apr 2008 16:21:07 +0900

Paul Visintainer wrote:

Is there an approach to analyzing the trend in odds ratios across the
ordered levels of a 3rd variable?  For example,

Suppose I have the risk of obesity in high school students by gender
over three different grades:

Grade  OR
10  1.5
11  1.9
12  2.2

There is a test of homogeneity to determine whether these ORs differ
across grade strata.  Is there a test to determine whether the pattern
is linear across strata?

--------------------------------------------------------------------------------

Are you looking for something other than -tabodds-?

Joseph Coveney

. webuse bdesop

. tabodds case alcohol [fweight = freq], or

---------------------------------------------------------------------------
    alcohol |  Odds Ratio       chi2       P>chi2     [95% Conf. Interval]
-------------+-------------------------------------------------------------
       0-39 |    1.000000          .           .              .          .
      40-79 |    3.565271      32.70       0.0000      2.237981   5.679744
     80-119 |    7.802616      75.03       0.0000      4.497054  13.537932
       120+ |   27.225705     160.41       0.0000     12.507808  59.262107
---------------------------------------------------------------------------
Test of homogeneity (equal odds): chi2(3)  =   158.79
                                 Pr>chi2  =   0.0000

Score test for trend of odds:     chi2(1)  =   152.97
                                 Pr>chi2  =   0.0000



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