Many DOE's need to be peformed over several days so considering and separation of random time variation in DOE analysis is an issue. As stated by Goos & Jones Randomized blocks in DOE are very useful to absorb random variation so fixed effects can be precisely estimated.
However in the JMP forward stepwise parameter selection module random effects can't be included; all blocks, also random time effect blocks, need to be treated as fixed effects. In forward selection it would be a major imporvement to also allow random effects so the old cumbersome backward selection can be avoided.