Blocking Factor

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

Blocking Factors - When all runs cannot be completed under the same environment (homogeneous conditions), exclusive of the factors themselves, blocking may be necessary. The maximum block size may be limited by such constraints as the number of runs that can be done in one day or shift. Blocking factors may not interact with main factors. Blocking factors are evaluated as random factors in an ANOVA.