Notice: On March 31, it was **announced** that Statalist is moving from an email list to a **forum**. The old list will shut down on April 23, and its replacement, **statalist.org** is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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 13:06:57 +0100 |

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! Carina -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Maarten Buis Sent: 31 May 2011 12:25 To: statalist@hsphsun2.harvard.edu Subject: Re: st: Recovering cell values from odds ratios On Tue, May 31, 2011 at 1:06 PM, King, Carina <c.king09@imperial.ac.uk> wrote: > I am trying to convert odds ratios back to the raw numbers. I have information on the number of cases and number of controls, as well as the odds ratios and confidence intervals. For that you also need the baseline odds, i.e. the odds of "success" (the expected number of successes per failure) for the controls. The odds for the cases are the odds ratio times the baseline odds. You can transform those odds to probabilities using the formula p = o/(1+o), where p is probability and o = odds. From there you can compute your counts by multiplying the probabilities with the number of controls or cases. Hope this helps, 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>

- Prev by Date:
**Re: st: Prediction for fractional logit** - Next by Date:
**Re: st: Prediction for fractional logit** - Previous by thread:
**Re: st: Recovering cell values from odds ratios** - Next by thread:
**Re: st: Recovering cell values from odds ratios** - Index(es):