Hi, Try this. > sd(unlist(sapply(1:dim(p)[1],function(i)rep(p[i,1],p[i,2])))) -- View this message in context: http://r.789695.n4.nabble.com/sd-mean-with-a-frequency-distribution-matrix-tp4703218p4703220.html Sent from the R help mailing list archive at Nabble.com.