Dylan Beaudette wrote: > Greetings, > > I am a bit confused by the results returned by the functions: > cohen.kappa {concord} > classAgreement {e1071} > > when using a two-way table. > > > for example, if I have an matrix A, and a similar matrix B (same > dimensions), then: > > matrix A and B can be found: > http://casoilresource.lawr.ucdavis.edu/drupal/files/a_40.txt > http://casoilresource.lawr.ucdavis.edu/drupal/files/b_40.txt > > A <- matrix(unlist( read.table('a_40.txt'), use.names=FALSE), ncol=14) > B <- matrix(unlist( read.table('b_40.txt'), use.names=FALSE), ncol=14) > If I interpret this correctly, you are considering the numbers in A and B to be nominal variables representing levels of some data attribute. What cohen.kappa wants is:
1(type=counts) a matrix of counts where each cell represents the number of methods (rows are different methods) that classified the data objects into levels (columns are different levels). 2(type=scores) a matrix of scores where each cell represents the level assigned by a method (rows again) to a data object (columns are data objects here). If your numbers are counts, you can get a sensible kappa for _each_ matrix. If your numbers are scores, you can get a sensible kappa by specifying type=scores for _each_ matrix As far as I can see, you are computing a sparsely populated table of the two matrices and passing that, and I don't see how that can give a meaningful result. I suspect that the numbers might be counts in the first place, but they are being used as scores. > Secondly, when using the classAgreements() function I get different numbers: > I'll let someone who knows more about the classAgreement function deal with this. Jim ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.