Sorry to disturb you, I should say that I do not have a deep knowledge of R or statics, but I have the following problem I think I could solve in R. I have a dataset that I can create with read.table which contains several columns, the first two are strings and the following integer numbers between 0 and 10 (yes they are marks) and I would like to do the following two things 1) grouping the numeric data accourding to the value of the second column and calculating the frequency of occurrence of each mark in the group (the second variable is a class name and I would like to say 10% of people of class IDONOTKNOW got 5 point for column 3 and the same for all other columns, of the order of ten numeric column) and 2) Building an occurency table for each class like the one given by table but with frequency replacing counts. Can someone help me ? I read the manuals but ..... Thank you very much Alberto Meroni caeyme at tin.it -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._