You are welcome.   You are comparing apples and oranges. If you want to compare the efficiency to the design you originally found (which does not conform to your desired restrictions) then you must evaluate the D-efficiency without the Block variable. This step will do that: %mktex(3 2 2 2 3 3 2 2, n=96, init=final(drop=block), options=check, interact=@2, seed=12345) When you impose restrictions, then you typically will get a lower D-efficiency. ... View more