Higher Order Test Designs
|Frequently the results of a designed
experiment (test) show:
This can be reflected in three statistics:
When these problems occur it may be due to model mis-specification. That is, the assumed underlying model may be inadequate to fit the data.
All tests assume an underlying model.
Using commercially available software currently enables the experimenter to assume only a linear (1st order) or quadratic (2nd order) model to analyze the data. This is a very limiting assumption.
What is needed is the ability use higher than 2nd order test designs and models. This can be done in two ways:
DOES has developed new higher order test designs which allow higher order model terms to be added.
The DOES test designs may be done sequentially:
Phase Test Points
This is a powerful approach to testing combining the small sample sizes in Phase I with the excellent data fitting in Phases III and IV.
To use DOES, Inc. services it is best to consult us in the planning and test design phase of a test. The data analysis is dependent on the selection of a test design.