On 10/07/2010 08:24 PM, David Winsemius wrote: > > On Oct 7, 2010, at 2:21 PM, Barth B. Riley wrote: > >> Dear list >> >> I would like to compute a Mantel-Haenszel chi-square in which the >> matching variable is a continuous variable. The MH chi-square is >> used to assess the relationship between two categorical variables at >> each level or strata defined by a third variable. Specifically I >> would like to know if there is a straightforward way to divide the >> matching variable into levels, in which each level has a minimum of >> 20 cases. Any information would be greatly appreciated. > > Why? What makes you think matching would be valuable? (...or even > valid, for that matter.)
What makes you think he has a choice? Matching is generally part of the design and data may already have been collected... For small-strata analyses look at clogit() in survival package. For cutting a continuous variable into roughly equal-sized strata use a combination og cut() and quantile() or (AFAIR) cut2() from one of Frank Harrell's packages. Finally, Breslow+Day in their classic book on case-control studies suggest replacing matched analysis by ordinary logistic regression with the effect of the matching variable modeled by a suitably high-order polynomial. -- Peter Dalgaard Center for Statistics, Copenhagen Business School Phone: (+45)38153501 Email: [email protected] Priv: [email protected] ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
