I've sent Martin Maechler details of a couple more bugs. (1) The line columns <- nrow(b.intervals) is wrong. It should be columns <- nrow(a.intervals) (2) Following each of the lines that generate values for id, one needs if (any(is.na(id))) id[is.na(id)] <- FALSE This is to deal with missing values in conditioning variables. I have made several sugegstions about warnings when there are missing values and labelling when show.given is FALSE. John Maindonald email : john.maindonald at anu.edu.au Statistical Consulting Unit, phone : (6249)3998 c/o CMA, SMS, fax : (6249)5549 John Dedman Mathematical Sciences Building Australian National University Canberra ACT 0200 Australia -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._