The primary objective of the trial is to Equatorial factor for joint effects among factors. You should understand the meaning of the affected joint before. We'll use a simple word is the "main effect" instead of "interaction" effects together (Interactions) is the failure of the variance of the response (Y) to have different values than when the test changed. the level of factor one (from level 1 to level 2, etc.) under each of the two factors.