Hi Massimo,
Professor Ripley has given you your answer.
It may help you further to know that factor levels aren't automatically
dropped when you subset a data set; you have to do it manually. Some time
ago I scrounged the following command from Andy Liaw's randomForest package:
it removes all
I need to perform the Exact Wilcoxon Mann-Whitney on a subset of my database.
Assuming that IPPO is my data frame and IPPOBIS is the subset my variable still
have 3 different levels and the function wilcox_test (package coin)
does not accept it.
I do not know how to overcome this problem.
ippo -
You have three levels of factor 'ippo' and data on two. That is not a
two-sample problem, as the error message says. Try
IPPOBIS$ippo - IPPOBIS$ippo[drop=TRUE]
And please use an informative subject line (see the posting guide).
On Thu, 12 Jul 2007, Cressoni, Massimo (NIH/NHLBI) [F] wrote:
I
