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From |
"King, Carina" <c.king09@imperial.ac.uk> |

To |
"'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: Recovering cell values from odds ratios |

Date |
Tue, 31 May 2011 13:42:29 +0100 |

The 'p' is the calculation from p=o/(1+o), and all the numbers were calculated, apart from the OR and the number of cases (218) and controls (14748). Taking 'unconsciousness' as the example: P= 3.54/(1+3.54) P= 0.77973 Then I multiplied by the number of cases first, then controls: 0.77973 * 218 = 170 (case unexposed) 218 - 170 = 48 (case exposed) 0.77973 * 14748 = 11500 (control unexposed) 14748 - 11500 = 3248 (control exposed) I'm not sure what you mean by the baseline odds ratio? Is that the reference group odds, which is 1? The paper presents the information as (OR, 95% CI), with the outcome being infection: Unconsciousness: 3.54 (1.93 - 6.00) No unconsciousness: 1.00 Is that clearer? I'm not sure I've presented that as well as I could...Thanks! Carina -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten Buis Sent: 31 May 2011 13:26 To: statalist@hsphsun2.harvard.edu Subject: Re: st: Recovering cell values from odds ratios On Tue, May 31, 2011 at 2:06 PM, King, Carina wrote: > Thanks for replying, but I think I'm a bit confused, I've attached the example I'm using: > > Cases: 218 > Controls: 14748 > Total: 14966 > > Risk factor: OR: p: case exposed(a): control exposed (b): case unexposed(c): control unexposed(d): > > Unconsciousness 3.54 0.77973 48 3248 170 11500 > Age >65 years 1.69 0.62825 81 5483 137 9265 > Female gender 1.66 0.62406 82 5544 136 9204 > > With the method you describe, the p for each comes out as shown above and consequently the numbers in each group. BUT when I then checked by recalculating the odds ratio from the numbers given, they all equal 1. What am I missing? Thank you! I don't understand what you did your example. What is p and where did it come from? Which part of those numbers did you compute and which were given. How did you do the computations? Where is the baseline odds? Generally, I think your example contains too many variables. The best strategy for problems like these is to start with an easy example, i.e. one variable, work till you understand that and than complicate matters till you get what you want. -- Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Recovering cell values from odds ratios***From:*Maarten Buis <maartenlbuis@gmail.com>

**References**:**st: Recovering cell values from odds ratios***From:*"King, Carina" <c.king09@imperial.ac.uk>

**Re: st: Recovering cell values from odds ratios***From:*Maarten Buis <maartenlbuis@gmail.com>

**RE: st: Recovering cell values from odds ratios***From:*"King, Carina" <c.king09@imperial.ac.uk>

**Re: st: Recovering cell values from odds ratios***From:*Maarten Buis <maartenlbuis@gmail.com>

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