This is zero! That causes serious problems when I'm using sum() or mean() to get the sum or mean of the non-missing data for each of several subjects, some of whom have all data missing (on some variable), and thus get a mean of 0. E.g., with apply(matrix1,1,sum,na.rm=T) some rows have all NA's, so the result I want is NA, but I get 0. Is there an ELEGANT workaround that gives NA instead of 0? -- Jonathan Baron, Professor of Psychology, University of Pennsylvania Home page: http://www.sas.upenn.edu/~baron -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._