I need help in developing the R syntax for a before-after control intervention design (BACI). Each cell of the 2-way table has multiple replicates-i.e., each replicate, in both the treatment and control groups, is measured both before and after the treatment period. I am having trouble in specifying the pairing (i.e., each replicate is measured both before and after the treatment). Thanks in advance for any help. Barry R. Noon Professor Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins, CO 80523 (970) 491-7905 [[alternative HTML version deleted]]