On 03-May-05 Frank E Harrell Jr wrote:
walmir-rodrigues wrote:
Dear Fellows,
How can I do to proced a step wise regression in R, if it�s possible ?
Thanks,
Walmir
Here is an easy approach that will yield results only slightly less valid than one actually using the response variable:
x <- data.frame(x1,x2,x3,x4,..., other potential predictors) x[,sample(ncol(x))]
:-) -Frank
Frank, you are a sneaky subversive! But you have given me a technical clue for a project long near to my heart (with Andy's important "random parsimony" refinement).
Now I get Andy's comment - missed before that we need to randomly set parsimony level then sample without replacement.
This is to implement software-driven Clinical Trials articles, for submission to standard peer-reviewed journals.
The underlying engine would be the dada-engine. For samples of what this can generate, visit
http://www.elsewhere.org/cgi-bin/postmodern
What a great site!
repeatedly (or click on the "To generate another essay, follow this link" link you will find just below the article generated; repeat ad libitum).
Also at the foot of the page, you will find links to explanations of how it works. See also
http://dev.null.org/dadaengine/
The basis is that articles of certain kinds have a predictable structure, and utilise terminology, phrases, sentence-structures and substantive elements drawn from typical usage, and are such that the real thing is indistiguishable from the results of sampling these elements at random, under the control of a rulebased recursive transition network automaton.
Tailor-made for Clinical Trials, methinks. (Mind you, someone once did a lot of work setting up the rulebase for the PostModern Lit Crit genre which is what you get in the above samples).
Great idea!!
Frank
Best wishes, Ted.
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University______________________________________________ [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
