hi, How can i calculate means with catergory of variable... like x y z 2 3 y 3 4 n 1 2 y 6 3 n 9 1 y 2 2 n 8 3 y i want to get mean of x and y with respective to its category(y,n) thanks... regards, Muhammad Faisal -- View this message in context: http://www.nabble.com/How-to-calculate--tp20516515p20516515.html Sent from the R help mailing list archive at Nabble.com.