I would start using the positional syntax, but that's because I first learned writing these out that way. So, for simplicity, suppose there were 3 areas and 4 periods. You have found a significant interaction, so it is appropriate to make comparisons between areas at the various time points: lsmestimate area*period 'Area 1, comparing period 1 to period 2' 1 -1 0 0 0 0 0 0 0 0 0 0, 'Area 1, comparing period 1 to period 3' 1 0 -1 0 0 0 0 0 0 0 0 0, 'Period 1, comparing area 1 to area 2' 1 0 0 0 -1 0 0 0 0 0 0 0; This gives 3 simultaneous comparisons. The first term is area1, with 4 periods, then a space (ONLY FOR READABILITY), then area2, with 4 periods, another space for readability, and then area3 with 4 periods. In this way, any combination of area by period lsmeans can be compared. Check out the Shared Concepts>ESTIMATE statement part of the documentation. It points out that LSMESTIMATE is constructed in the same way as the ESTIMATE--it just uses the lsmeans rather than the solution vector. Steve Denham
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