You can use 'cut' to create the breaks.. Actually there are 8 in the 3-4 range: Outcome predictor 1 0 1 2 1 2 3 1 2 4 0 3 5 0 3 6 0 2 7 1 3 8 1 4 9 1 4 10 0 4 11 0 4 12 0 4 > cut(x.1$p, breaks=c(0,2,4)) [1] (0,2] (0,2] (0,2] (2,4] (2,4] (0,2] (2,4] (2,4] (2,4] (2,4] (2,4] (2,4] Levels: (0,2] (2,4] > x.c <- cut(x.1$p, breaks=c(0,2,4)) > tapply(x.1$O, x.c, function(x)sum(x==1)/length(x)) (0,2] (2,4] 0.500 0.375 > __________________________________________________________ James Holtman "What is the problem you are trying to solve?" Executive Technical Consultant -- Office of Technology, Convergys [EMAIL PROTECTED] +1 (513) 723-2929 "Stephen Choularton" <[EMAIL PROTECTED]> To: "R Help" <r-help@stat.math.ethz.ch> Sent by: cc: [EMAIL PROTECTED] Subject: [R] plotting percent of incidents within different 'bins' ath.ethz.ch 01/05/2005 14:34 Hi Say I have some data, two columns in a table being a binary outcome plus a predictor and I want to plot a graph that shows the percentage positives of the binary outcome within bands of the predictor, e.g. Outcome predictor 0 1 1 2 1 2 0 3 0 3 0 2 1 3 1 4 1 4 0 4 0 4 0 4 etc In this case there are 4 cases in the band 1 - 2 of the predictor, 2 of them are true so the percent is 50% and there are 7 cases in the band 3 - 4, 3 of which are true making the percentage 43% . Is there some function in R that will sum these outcomes by bands of predictor and produce a one by two data set with the percentages in one column and the ordered bands in the other, or alternately is there some sort of special plot.???? that does it all for you? Thanks Stephen [[alternative HTML version deleted]] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html