pg_0042
5.
Process Improvement
5.3.
Choosing an experimental design
5.3.3.
How do you select an experimental
design.
A design is
selected
based on the
experimental
objective
and the
number of
factors
The choice of an experimental design depends on the objectives of the
experiment and the number of factors to be investigated.
Experimental Design Objectives
Types of
designs are
listed here
according to
the
experimental
objective
they meet
Types of designs are listed here according to the experimental objective
they meet.
Comparative objective: If you have one or several factors under
investigation, but the primary goal of your experiment is to make
a conclusion about one a-priori important factor, (in the presence
of, and/or in spite of the existence of the other factors), and the
question of interest is whether or not that factor is "significant",
(i.e., whether or not there is a significant change in the response
for different levels of that factor), then you have a comparative
problem and you need a comparative design solution.
q
Screening objective: The primary purpose of the experiment is
to select or screen out the few important main effects from the
many less important ones. These screening designs are also
termed main effects designs.
q
Response Surface (method) objective: The experiment is
designed to allow us to estimate interaction and even quadratic
effects, and therefore give us an idea of the (local) shape of the
response surface we are investigating. For this reason, they are
termed response surface method (RSM) designs. RSM designs are
used to:
Find improved or optimal process settings
r
q
5.3.3. How do you select an experimental design.
http://www.itl.nist.gov/div898/handbook/pri/section3/pri33.htm (1 of 3) [5/7/2002 4:01:45 PM]
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