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From | Roger Newson <r.newson@imperial.ac.uk> |
To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
Subject | Re: st: is Kendall's tau the best correlation coeficient for binary varibles? |
Date | Wed, 8 Sep 2010 17:43:00 +0100 |
So, if -x- and -y- are 2 binary variables, with values 0 for a negative outcome and 1 for a positive outcome, then you can type
somersd x y, transf(z) tdistto get a confidence interval for the difference between the proportion of y-positives in the x-positives and the proportion of y-positives in the x-negatives. And you can type
somersd y x, transf(z) tdistto get a confidence interval for the difference between the proportion of x-positives in the y-positives and the proportion of x-positives in the y-negatives. Both of these confidence intervals are defined using the Normalizing and variance-stabilizing hyperbolic arctangent or z-transformation, to define symmetric confidence intervals for the z-transformed differences between proportiions, and the more useful asymmetric confidence intervals for the untransformed differences between proportions.
I hope this helps. Best wishes Roger Roger B Newson BSc MSc DPhil Lecturer in Medical Statistics Respiratory Epidemiology and Public Health Group National Heart and Lung Institute Imperial College London Royal Brompton Campus Room 33, Emmanuel Kaye Building 1B Manresa Road London SW3 6LR UNITED KINGDOM Tel: +44 (0)20 7352 8121 ext 3381 Fax: +44 (0)20 7351 8322 Email: r.newson@imperial.ac.uk Web page: http://www.imperial.ac.uk/nhli/r.newson/ Departmental Web page: http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/ Opinions expressed are those of the author, not of the institution. On 08/09/2010 17:16, jl591164@albany.edu wrote:
Dear Statalist, I need to do a correlation matrix of all my study variables. Most of them are binary variable, and two are continuous variables. Is Kenall's tau the test coefficient to use to get the correlation matrix of my study variables? Any advice is highly appreciated. Junqing * * 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/