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Key steps for DOE
A checklist of practical considerations
Planning to do a sequence of small experiments is often better than
relying on one big experiment to give you all the answers
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Getting good results from a DOE involves these seven steps:
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Set objectives
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Select process variables
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Select an experimental design
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Execute the design
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Check that the data are consistent with
the experimental assumptions
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Analyze and interpret the results
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Use/present the results (may lead to further runs or DOE's).
Important practical considerations in
planning and running experiments are
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Check performance of gauges/measurement devices first.
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Keep the experiment as simple as possible.
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Get the runs over with as quickly as possible.
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Check that all planned runs are feasible.
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Watch out for process drifts and shifts during the run.
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Avoid unplanned changes (e.g. swap operators at half time).
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Allow some time (and back-up material) for unexpected events.
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Obtain buy-in from all parties involved.
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Maintain effective ownership of each step in the experimental plan.
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Preserve all the raw data�do not keep only summary averages!
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Record everything that happens.
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Reset equipment to its original state after the experiment.
The Sequential or Iterative Approach to DOE
It is often a mistake to believe that �one big experiment will give
the answer.�
A more useful approach to experimental design is to recognize that while
one experiment might give a useful result, it is more common to perform
two or three, or maybe more, experiments before a complete answer is attained.
In other words, an iterative approach is best and, in the end, most economical.
Putting all one�s eggs in one basket is not advisable.
The reason an iterative approach frequently works best is because it
is logical to move through stages of experimentation, each stage supplying
a different kind of answer. |
