Dear Sir
This is my second email that I send you. In fact I become so confused
in using appropriate software for my design. As I told you before I
am looking for an array that include one 12LF , one 2LF and one 3LF
and I find L18(2^1*3^7). For this purpose I upgrade six 3LFs to have
one 12LF (because sum of their DOF is 12 that can be suitable for my
12LF). So I use column 2,3,4,5,6,7 and according to triangle for 3-
level orthogonal array, column 4 and 7 were omitted. Now my question
is "am I use correct orthogonal array?" and "Is there any Software
(e.g. Qualitek4) that can upgrade six 3LF to one 12LF?" or you offer
another way to solving this problem?
I hope you help me because I didn't find anyone that can answer me
and my project has stopped because of this problem.

Best Regards
E. Abasi
School of Industrial engineering, Iran,Azad university

Answer:
To: E. Abasi,

You can use Qualitek-4 software (www.nutek-us.com/wp-q4w.html ) to
design experiments with factors at 2, 3 and 4 levels. I'm not aware
of any software that will let you design experiments with 12 level
factor.

For multi-variable study, you should not have to have a factor at
higher than 4 levels. If you must test a factor at 12 levels,
consider doing so with a separate ONE FACTOR tests.

Good luck with your projects.

- Ranjit Roy Nutek, Inc. 2/9/09