Hi Susan and Steve, First, Susan what a astonishing desing exposition, I understand you plot/mane consideration, we need to take those points into consideration. Yes, my depth factor are soil core samples on each b leves plot and so they are destructive samples. The subject I have use for the random factors is ‘subject=Block*A*B’, and not only Block. I really need to try out all option using Proc Glimmix, because of data distribution type. So, I have run using your suggested code as below: #1 random Depth Time / type=sp(powa)(Depth Time) subject=Block*A*B residual; (But I got this ERROR: Only one residual effect is permitted per RANDOM statement). So, I removed the term “residual” from the end of the code #1 (I don’t know if it correct to do so?), and then it runs fine, the results differ from those using Steve suggestion (below #2). #2 random _residual_ / type=sp(powa)(Depth Time) subject= Block*A*B; Using Steve suggestion (#1) (considering default distribution), result are similar to those obtained from Proc mixed suggest by Steve first. I'm still not convinced if the factor levels scale I use is correct. Thank you,
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