xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx hello all, I have an array c as follows 1 23 12 1 34 15 1 45 67 1 45 87 2 78 23 2 65 19 2 45 90 2 70 32 Col 1 indicates treatment, col2 is the observed readings and col3 is some summary statistic I have calculated after breaking the ties in col 2 arbitrarily. Now I want to average the statistics of the tied values. So, in col 3 for each of the reading of 45 , I now want (67+87+90)/3 = 81.33 1 23 12 1 34 15 1 45 81.33 1 45 81.33 2 78 23 2 65 19 2 45 81.33 2 70 32 Can someone please help me do this in R? Thanks in advance Warm regards ~S