Hi Joshua: how to do a permutation test on the following sample with the sample size in 20000 : id weight P VALUE 100 100 101 200 102 200 103 150 ....... Thanks -- View this message in context: http://r.789695.n4.nabble.com/choosing-a-random-sample-by-precentage-tp2299509p2299529.html Sent from the R help mailing list archive at Nabble.com.