Fixed Effects

The following is an excerpt on DOE designed experiment techniques from Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller.

Fixed Effects - Fixed effects are factors chosen at specific levels of interest, spanning a region of interest, for which a systematic effect on the model response is expected. In a separate context, factors are said to be fixed when held at a constant level during an experiment. The alternative to a fixed effect is a random effect.