Flash response:
1) Are the levels fixed by some characteristic of the process? they
look continuous, and you could do much better if they were, and you
could select different intermediate levels.
2) the number of levels can be what you want of it. Some good
response surface designs use 5 levels. some use more.
3) Factor B levels are equally spaced, which is good. Factor A
levels are not evenly spaced. A full factorial will not give you a
'clean' design - Without doing the math, I don't believe it will be
orthogonal, even if you did do all the combinations.
4) what are you going to do with the results of this experiment? If
you wish to build a model of the system behavior, then a full factorial
type approach is a waste of your effort, time, and experimental runs.
5) Suggest you look at a Response model, with maybe 3-5 levels in
both factors, but using a proper RSM type design. If you do it
properly, you can avoid a single 'corner' point and recover it
mathematically.
6) I'd also ask if you have hard reason to believe that a RSM type
model, which will get you quadratic terms in a model, is in fact worth
doing (financial/your time costs) the first time out? If little prior
information is available, it would probably be better to do a simpler,
2-level factorial first, if at all possible. Doing this will teach you
a great deal [that you probably don't already know]. Your choice here,
but remember - most people overestimate their knowledge level :)
7) You haven't discussed the response yet. Please spend some time
thinking about that, too.
More later, if this helps at all. Let me know.
Jay
[EMAIL PROTECTED] wrote:
> Hi,
>
> I have two factors A and B and I want to run a DOE to study my response.
> My factor B is at 3 levels; (900, 1450 and 2000) , my factor A is at 4
> levels 35, 65, 80 and 105.
> First of all is it right to have one factor at 4 levels. I have
> encountered situations where the factors are either at 2 levels or 3
> levels.?
> This will require me to have 12 runs for a full factorial, right?
> Also, I do not want to run only the level 35 of factor A with the level
> 900 of factor B. If I remove the combination 35, 1450 and 35, 2000;
> I'll have only 10 runs and the resulting design space will not be
> orthogonal. How do I tackle this problem?
> Is there a different design that you would suggest.
> Thanks for your help.
> SH Lee
>
>
> Sent via Deja.com
> http://www.deja.com/
>
>
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--
Jay Warner
Principal Scientist
Warner Consulting, Inc.
4444 North Green Bay Road
Racine, WI 53404-1216
USA
Ph: (262) 634-9100
FAX: (262) 681-1133
email: [EMAIL PROTECTED]
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