Here's another set of frequently asked questions (FAQs) about doing design of experiments (DOE), plus alerts to timely information and free software updates. If you missed previous DOE FAQ Alerts, please click on the links at the bottom of this page. If you have a question that needs answering, click the Search tab and enter the key words. This finds not only answers from previous Alerts, but also other documents posted to the Stat-Ease web site.
Feel free to forward this newsletter to your colleagues. They can subscribe by going to http://www.statease.com/doealertreg.html. If this newsletter prompts you to ask your own questions about DOE, please address them via mail to: StatHelp@StatEase.com.
Here's an appetizer to get this Alert off to a good starta commentary about quantity versus quality from Josh Wolfe in his April 8th Nanotech Weekly Insider (http://www.forbeswolfe.com). "An art teacher split her class into two equal groups. Both would work on making ceramics. Group A would be graded only on how many pieces they produced: the quantity of their work. Group B would be graded only on how good their finished products were: the quality. The teacher would base her decision on Group A (the quantity people) by weighing their final output on a scale. 100 pounds of pottery would get an A, 90 pounds would get a B and so on. Group B only had to make one pot, but it had to be flawlessly perfect for an A...Surprisingly, the best quality pottery came from Group A, the group focused only on quantity. While they were all hammering away spitting out piece after piecethey were unconsciously learning from their mistakes and improving their quality. Meanwhile Group B, focused on quality, sat around discussing how best to perfect the design, and ultimately had nothing but a pile of clay to show." Put that in your pot and stew on it!
Here's what I cover in the body text of this DOE FAQ Alert (topics that delve into statistical detail are designated "Expert"):
1. FAQ: Why solutions
vary from numerical optimization performed by Design-Expert®
From: United Kingdom
"Why is it that I get a slightly different solution set each time I perform numeric optimization, even if I don't change any of my goals or criteria for desirability?"
Answer (from Stat-Ease Consultant
Design-Expert version 6 allows users to increase the number of random searches from the default of 10 to a maximum of 99. (Version 7 will increase the allowable searches to 999.) The program also provides a duplicate solution filter for which "Epsilon," the difference between two results considered to be the same, can be adjusted somewhat. As it's increased, the number of unique solutions decreases and vice-versa."
(Learn more about optimization by attending the three-day computer-intensive workshop "Response Surface Methods for Process Optimization." See http://www.statease.com/clas_rsm.html for a complete description. Link from this page to the course outline and schedule. Then, if you like, enroll online.)
2. Info alert: Link to several new DOE articles and textbooks
Read "Experimental Design Optimizes Assay Automation" posted on the Internet by "Inside Biomed" (a Quality Digest publication) at http://makeashorterlink.com/?F51552AFA to learn how an innovative blend of hardware, software and the right training in statistical know-how simplified research automation. The authors are Thomas Erbach and Lisa Fan from Beckman Coulters Biomedical Research Division, and Stat-Ease consultant Shari Kraber.
The Online Exclusive for the April issue edition of "Solutions!" magazine features an article by Richard Burnham on how Don Smith of Stora Enso brought in DOE training to banish their "Purple- Paper Blues." It is available for viewing at http://www.tappi.org/index.asp?pid=32071&ch=1.
On March 28 I received a press release announcing publication
of "Experimental Design for Formulation" (ASA-SIAM
Series on Statistics and Applied Probability 15) by Wendell
F. Smitha frequent contributor to Stat-Ease. Wendell's
new book garnered this rave review from fellow author John
A. Cornell, Professor Emeritus of Statistics, University of Florida (and reigning
guru of mixture design): "...heartiest congratulations
on a job well done. I am very impressed by the amount of
discussion in the text devoted to the topics of model building
and model evaluation and I hope the software companies that
support the fitting of mixture models will incorporate the
topics discussed in the text in their software." I
can assure Professor Cornell that the upcoming new version
7 of Design-Expert software from Stat-Ease will indeed incorporate
many new features instigated by Wendell Smith. His book
can be ordered direct at http://ec-securehost.com/SIAM/SA15.html.
It's intended for formulators in industry as well as senior
undergraduate and beginning graduate students in statistics.
However, as noted in the PR, be forewarned that before reading
this book you'd best familiarize yourself with basic experimental
designs and methods
Also, I should mention that Doug Montgomery, Professor
of Engineering at Arizona State University, has published
his 6th Edition of "Design and Analysis of Experiments."
He showed it to me in February at the American Society of
Quality (ASQ) Six Sigma Conference. The most obvious change
is the cover it now fits into a new scheme by the
publisher that ties together the whole series of statistical
books authored in whole or part by Professor Montgomery
PS. For a great discussion on Taguchi versus more modern approaches to DOE, see Montgomery's supplement to Chapter 12 of his book at http://makeashorterlink.com/?J62B42EFA.
(For a top-shelf selection of books on DOE, including the new one from Montgomery, see http://www.statease.com/prodbook.html.)
From: P. B. Dhanish, Lecturer,
Department of Mechanical Engineering National Institute of Technology
For more discussion, please see "Adding centerpoints" in the Engineering Statistics Handbook at http://www.itl.nist.gov/div898/handbook/pri/section3/pri337.htm."
I appreciate the insights and link from Professor Dhanish.
4. Events alert: Come see us at the ASQ Quality & Improvement Conference in
Seattle and a conference on coatings in New Orleans
Come see Stat-Ease in Booth #414 at the ASQ World Conference on Quality & Improvement in Seattle, Washington, on May 16-18. Attend talk T205 titled "PCR Process Optimized via Split-Plot Design" by Pat
Whitcomb on Tuesday, May 17th. See http://wcqi.asq.org/ for details on the conference.
On May 19th in New Orleans, I present "How to Design and Analyze Mixture Designs that Include Process Factors and/or Categorical Variables" at a conference on Research Methods in the 21st Century sponsored by the Federation of Societies for Coatings Technology. For more details, see http://makeashorterlink.com/?E34663FFA.
Click http://www.statease.com/events.html for the complete list of appearances by Stat-Ease professionals. We hope to see you sometime in the near future!
5. Workshop alert: See when and where to learn about DOE
See http://www.statease.com/clas_pub.html for schedule and site information on all Stat-Ease workshops open to the public. To enroll, click the "register online" link on our web site or call Stat-Ease at 1.612.378.9449. If spots remain available, bring along several colleagues and take advantage of quantity discounts in tuition, or consider bringing in an expert from Stat-Ease to teach a private class at your site. Call us to get a quote.
I hope you learned something from this issue. Address your general questions and comments to me at: Mark@StatEase.com.
Mark J. Anderson, PE, CQE
PS. Quote for the monthKeeping it simple and stupid:
"For every complex question
there is a simple answer, and it is wrong."
Trademarks: Design-Ease, Design-Expert and Stat-Ease are registered trademarks of Stat-Ease, Inc.
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