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OFAT (One Factor at A Time)

OFAT = One Factor at A Time

Supporting References
DOE = Design of Experiments, aka Statistically Designed Experiment

  • OFAT requires more effort and data, while providing less information than DOE.
  • OFAT is not 'orthogonal' and usually does not allow the estimation of interactions between factors.
  • OFAT extrapolates within the design space, while DOE interpolates.
  • Using three or more levels in OFAT commonly leads some to believe that they can estimate higher-order effects (quadratic, cubic, etc.), but this is not an effective method.  See Three Level Factorial Design Matrix for an improved approach.  Also note Central Composite designs (CCD).
  • OFAT does not provide an effective way to add to the Design Structure in subsequent designs.
  • OFAT tends to ignore the many pitfalls of not using a randomized order to testing the various treatments.


OFAT vs DOE ‎‎‎‎(two level)‎‎‎‎