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Process Improvement

5.4.

Analysis of DOE data

5.4.6.

How to confirm DOE results

(confirmatory runs)

Definition of

confirmation

runs

When the analysis of the experiment is complete, one must verify that

the predictions are good. These are called confirmation runs.

The interpretation and conclusions from an experiment may include a

"best" setting to use to meet the goals of the experiment. Even if this

"best" setting were included in the design, you should run it again as

part of the confirmation runs to make sure nothing has changed and

that the response values are close to their predicted values. would get.

At least 3

confirmation

runs should

be planned

In an industrial setting, it is very desirable to have a stable process.

Therefore, one should run more than one test at the "best" settings. A

minimum of 3 runs should be conducted (allowing an estimate of

variability at that setting).

If the time between actually running the experiment and conducting the

confirmation runs is more than a few hours, the experimenter must be

careful to ensure that nothing else has changed since the original data

collection.

Carefully

duplicate the

original

environment

The confirmation runs should be conducted in an environment as

similar as possible to the original experiment. For example, if the

experiment were conducted in the afternoon and the equipment has a

warm-up effect, the confirmation runs should be conducted in the

afternoon after the equipment has warmed up. Other extraneous factors

that may change or affect the results of the confirmation runs are:

person/operator on the equipment, temperature, humidity, machine

parameters, raw materials, etc.

5.4.6. How to confirm DOE results (confirmatory runs)

http://www.itl.nist.gov/div898/handbook/pri/section4/pri46.htm (1 of 2) [5/7/2002 4:02:07 PM]