I'm trying to determine if a set of data is normal from a qq plot but seem to be having a bit of difficulty. I have a file of the following form 9 36 3 37 6 38 7 39 ..... where the left column is the frequency of the number in the right column. I've found the probabilities of each number and put it in a file of the form 36 .0009 37 .0003 38 .0006 39 .0007 where the first column is the number and the second is the probability of that number. Now what I've done so far is as follows: null=read.table("probfile.txt",header=FALSE) #Prob file is the 2nd file where $V1 is the number and $V2 is the probability and I want to do x=qnorm(null$V2, ... ) but I don't know how to get the mean and sd from those 2 files. When I looked up mean() and sd(), I had to give a vector of numbers. As I only have the number of occurances and their probability, I can't really get a vector of this data unless I make another file that has the frequency of the numbers written out -- which is intractable given I have 10000000 data points. I mean I could write a quick program to get the mean (which I did in perl) but I'd rather not do that for the sd as I am sure there is an easier way to do this. Either way, once I have the qnorm stored in x, all I have to do is qqnorm(x) right? -- View this message in context: http://www.nabble.com/QQplots-of-probability-vector-data-tp24145321p24145321.html Sent from the R help mailing list archive at Nabble.com.