RE: [R] generalized matrix product ?

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Sat 30 Apr 2005 - 04:39:40 EST


> From: George_Heine@blm.gov
>
> Is there available in R a generalized inner product or matrix product,
> similar to 'outer(x,y, fun)', where one can specifiy an
> arbitrary function
> in place of ordinary multiplication?
>
> Here's my application. I frequently analyze user
> questionnaires from our
> HR/training department. These have questions of the form
> "please rate your skill in task X",
> and other questions of the form
> "Have you taken course Y?" (or "How many years since
> you have taken
> course Y?")
>
> I look at rank correlation between the (suitably ordered) vectors of
> responses to a question in the first group and a question in
> the second
> group. (The two vectors have the same length, but I want to
> replace the
> standard inner product with a different operation; in this case, rank
> correlation) Repeat the process across all possible pairs of
> questions.
>
> Is there a way to accomplish this without nested 'for' statements?

I don't see how you can generalized inner product to get to rank correlations. Rank correlations are not computed by simply replacing the multiplication in the inner product with something else, but they replace the data values with ranks, and then compute the usual correlations on the ranks.

If you want to generate rank correlation matrix, use cor(..., method="spearman").

Andy  

> Hope this is clear - thanks!
> <>=<>=<>=<>=<>=<>=<>=<>=<>=<>=<>
> George Heine, PhD
> Mathematical Analyst
> National IRM Center
> U.S. Bureau of Land Management
> voice (303) 236-0099
> fax (303) 236-1974
> cell (303) 905-5382
> pager gheine@my2way.com
> <>=<>=<>=<>=<>=<>=<>=<>=<>=<>=<>t
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>
>
>



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Apr 30 04:44:37 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:31:31 EST