I have 4 factors & plan on doing 8 runs. I'm wondering if I can block 4 of the runs for the 1 month I run those experiments, and 4 of the runs the next month that I run the experiment - basically 2 blocks of size 4. Would adding month as a blocking factor mean I now have 5 factors in my design? How would that look in a model & what would that alias structure look like?
Somewhat related - I'd like to account for lot# of a raw material in my design, but I can't really block it - it seems most runs have one of 3 or 4 lot #'s so I can't do 2 levels of lot # - would I account for this as a covariate? How would that look in a model?
