__Calculator for confidence intervals of odds ratio
in an unmatched case control study using the null hypothesis to provide an estimate. For example groups of cases and controls
studied to assess the outcome after a particular intervention. __

__
____This calculator provides the Peto odds ratio and the observed - expected differences, together with the variance of the observed - expected difference. This allows you to calculate the result of a meta-analysis of different studies. Refer to the Cochrane Collaboration for details.__ This calculator
works off-line. (IE4)

#### Programme written by DJR Hutchon. Enter data into the boxes "A","B","C",and
"D"

This calculator is for educational use. It is believed accurate but no
responsibility for accuracy of the results is accepted by the author. David J R
Hutchon BSc, MB, ChB, FRCOG Consultant Gynaecologist, Memorial Hospital,
Darlington, England.

This calculation is based on the null hypothesis and provides an estimate of the true odds ratio. Under the null hypothesis that treatment has no effect on outcome, the difference between the observed and the expected would have zero difference and variance. The advantage of this approach over direct calculation is that it will accept zero results without generating infinity. You are welcome to keep this page and use the calculator
off-line. I would appreciate an E-mail if you find it useful enough to do so.
E-mail to me at DJRHutchon@Postmaster.co.uk

24/3/2006

Reference
Chalmers et al Effective Care in pregnancy and childbirth. p63