Hi: I am trying to migrate from Systat to R but I am facing my first challenge. While I easily can get weekly co-variance for my data, I can't seem to acomplish this with R ( I can't figure out how is done) If interested in looking a sample of my data, please check the data below. In Systat from Week 28 I get a covariance of 1055 fish. Thanks in advance Fish Passage Week number Weekly Covariance 0 26 0 0 27 0 0 27 0 27 0 27 0 27 0 27 0 27 0 28 1055 0 28 71 28 132 28 223 28 224 28 218 28 228 29 224 29 488 29 525 29 80 29 417 29 82 29 413 30 373 30 914 30 213 30 651 30 521 30 979 30 177 31 604 31 824 31 1190 31 926 31 1257 31 1071 31 1709 32 1166 32 704 32 1424 32 2586 32 1163 32 647 32 Felipe D. Carrillo Fishery Biologist US Fish & Wildlife Service Red Bluff, California 96080 --------------------------------- [[alternative HTML version deleted]]