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Re: st: Query for OR calculation


From   "Svend Juul" <[email protected]>
To   <[email protected]>
Subject   Re: st: Query for OR calculation
Date   Fri, 20 Apr 2007 20:29:44 +0200

Todd wrote:
 
For an HIV programme in Benin we had 59 persons lost to follow-up. 
We were able to do home visits for 41 persons, after which 33
returned to clinical care. Of those 18 we were not able to visit, 
only 8 returned to clinical care.
 
What is the most efficient way to create a mini database to define
the odds ratio...the odds of returning for clinical care after a
home visit as compared to those not visited. I could simply go
into the Data Editor of a blank database and enter the numbers...
but Id like to type in the data.
    
Visited 41 (33 reintegrated)
Not Visited 18 (8 reintegrated) 
Total 59
 
----------------------------------------------------
 
Michael and Sebastian gave valid suggestions. But since you ask for
odds ratios, the most direct way is -cci- :
 
. cci 33 8 8 10
                                                         Proportion
                 |   Exposed   Unexposed  |      Total     Exposed
-----------------+------------------------+------------------------
           Cases |        33           8  |         41       0.8049
        Controls |         8          10  |         18       0.4444
-----------------+------------------------+------------------------
           Total |        41          18  |         59       0.6949
                 |                        |
                 |      Point estimate    |    [95% Conf. Interval]
                 |------------------------+------------------------
      Odds ratio |          5.15625       |    1.311065    20.46528 (exact)
 Attr. frac. ex. |         .8060606       |    .2372611    .9511368 (exact)
 Attr. frac. pop |         .6487805       |
                 +-------------------------------------------------
                               chi2(1) =     7.66  Pr>chi2 = 0.0056
 
You could also create your "database" with the -input- command_
 
   clear
   input visit reint n
   0 0 10
   0 1 8
   1 0 8
   1 1 33
   end
 
and use -n- as frequency weight:
 
   cc reint visit [fweight=n]
 
or -expand- the dataset:
 
   expand n
   cc reint visit
 
Hope this helps
Svend
 
 
________________________________________________________ 
 
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6 
DK-8000 Aarhus C,  Denmark 
Phone, work:  +45 8942 6090 
Phone, home:  +45 8693 7796 
Fax:          +45 8613 1580 
E-mail:       [email protected] 
_________________________________________________________ 

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