Date:         Sat, 9 Mar 1996 07:41:43 -0400
Reply-To:     Mitch Gallant <mgallant@PILOT.IH.NAVY.MIL>
Sender:       "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From:         Mitch Gallant <mgallant@PILOT.IH.NAVY.MIL>
Subject:      Pushing the ADXXVERT macro

Friends of SAS,
 
I am a novice SAS user who has a fair amount of experience with the regular
factorial-type experiments.  I have been learing how to use SAS as a tool
for those types of designs.  The area of mixture designs is however rather
new to me.  I seek your help in understanding a specific macro, the
ADXXVERT macro. I have given my difficultly and lot of thought.  Now I am
asking the assistance of those more experienced than I.
 
An innoucous example,
 
I wish to make the best tasting stew using water, beef, carrots, and
potatos.  In this example, the water must remain at a concentration of 0.50
for all treatments.  The beef, carrots, and taters can vary 0 - 0.50.  I
wish to model the taste and appearance responses.  Assuming I need a
quadratic model, I have tried variations in the ADXXVERT statement as in
the following code:
 
%ADXGEN
%ADXMIX
%ADXINIT
%ADXXVERT (stew, bee -.5 /car -.5 /pot -.5 /wat .5-.5)
PROC PRINT etc...
 
This line produces a data set with a number of duplicate treatments which I
think are the result of the macro treating the water as two separate of
levels of 0.50 and 0.50.
 
Question 1:  Is there a way to format the statement to not produce these
duplicate levels? Or better stated, what statement(s) should I use to
generate a "good" design given the experiemental constraints?
 
Question 2:  Assuming I would like the final design to include some measure
of the variation, what is the minimum design size?  Do I use PROC OPTEX?
 
Geometrically, I visualize the tha above example as a pyramid with an
intersecting plane at water = 0.50.  One approach may be to simplify my
mixture to a three component mixture, and scale my "recipes" in the
generated design by 0.50.  Right now I don't fully know what implications
this scaling would have on my analysis.  Also I can't find how to constrain
the macro to force three ingredients in a three mixture design to sum 0.50
instead of 1.0.  Any opinions?
 
Thanks so much for your attention +<:)
 
Mitch Gallant
Chemist, Naval Surface Warfare Center/Indian Head Div.
Indian Head, MD
301/743-4272 (voice mail)
mgallant@pilot.ih.navy.mil