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Process Improvement

5.3.

Choosing an experimental design

5.3.3.

How do you select an experimental design.

5.3.3.8.

Improving fractional factorial

design resolution

Foldover

designs

increase

resolution

Earlier

we saw how fractional factorial designs resulted in an alias

structure that confounded main effects with certain interactions. Often it

is useful to know how to run a few additional treatment combinations to

remove alias structures that might be masking significant effects or

interactions.

Partial

foldover

designs

break up

specific

alias

patterns

Two methods will be described for selecting these additional treatment

combinations:

Mirror-image foldover designs

(to build a resolution

IV design from a resolution III design)

Alternative foldover designs

(to break up specific

alias patterns).

5.3.3.8. Improving fractional factorial design resolution

http://www.itl.nist.gov/div898/handbook/pri/section3/pri338.htm [5/7/2002 4:02:03 PM]