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 the previous DOE FAQ Alert, 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.
For an assortment of appetizers to get this Alert off to a good start, see the five new entries since last month's issue that I added to http://statsmadeeasy.net. These include morbid data reported under the heading of "Stats that will be the death of you." I was reminded about these odds of dying from particular, many of them peculiar, causes upon hearing the sad news of crocodile hunter Steve Irwin's recent demise. Perhaps it may not be such a surprise for such a risk-taker, but what a way to go! :(
Topics in the body text of this DOE FAQ Alert are headlined below (ones that delve into statistical detail are designated "Expert"):
1. Faq: Why do you favor half vs full normal plot of effects?
1. FAQ: Why do you favor half vs full normal plot of effects?
I mentioned how much better half-normals are for picking effects at an ASQ talk attended by Stu Hunter, co-author of the landmark book, "Statistics for Experimenters." Afterwards he told me that Stat-Ease was right and that they (he and co-authors George Box and Bill Hunter) had it that way (half-normal) in their original manuscript, but just before publication the inventor of this graphical method for choosing effects, Cuthbert Daniel, wavered back to full-normal. Stu said their book went to press just after Daniel reversed himself back to favoring the half-normal again! Obviously, the choice of half versus full normal plots is debatable. That's why we provide the option for both in our software. The newest version* provides color-coding to see at a glance whether effects are positive or negative.
Do any of you readers have a strong preference?
*See http://www.statease.com/soft_abs.html for details and link from there to free 45-day fully-functional trials of version 7 of Design-Ease and/or Design-Expert software.
2. FAQ: How does the Pareto chart help choose effects?
(These questions were originally published in the February 2003 DOE FAQ Alert — http://www.statease.com/news/faqalert3-2.html )
From: User in United Kingdom "Mark, I am really interested in being able to get an ordered bar [Pareto] chart out of your software, which shows the importance of the effects in rank order as an alternative to the half-normal plot. I feel that this provides an intuitive way of identifying the most important effects. We have found the half- normal plot difficult to explain to scientists. Is there any way of doing this in Stat-Ease software, or any plans to put it into future versions?"
From: North Carolina statistician "Mark, with respect to future upgrades, may I suggest that a
(Learn more about choosing effects and other DOE basics by attending the three-day computer-intensive workshop "Experiment Design Made Easy." For a course description, see http://www.statease.com/clas_edme.html. Link from this page to the course outline and schedule. Then, if you like, enroll online.)
3. Info alert: Attention coatings experimenters — Drawing for free handbooks that include a section on DOE (link to content)
(Sorry, due to the high cost of shipping, this offer applies only to residents of the United States and Canada.) Simply reply to this e-mail before September 12 if you'd like a chance at one of two free copies of the "Coatings Technology Handbook," 3rd Ed. (CRC). Winners, who will be drawn at random, will be notified and asked to supply their shipping address. This latest edition of the Handbook, which can be seen at http://tinyurl.com/mfj8t , includes a new chapter (15) on "Design of Experiments for Coatings" authored by Pat Whitcomb and myself. You can see the content in our original manuscript posted at http://www.statease.com/pubs/doe_for_coatings.pdf.
4. Events alert: Many Stat-Ease appearances lined up this Fall!
Look over this line-up and see if any of our events scheduled this Fall will be convenient for you to attend and/or affiliated with a conference in your field of expertise:
- Minnesota Quality Conference, Bloomington, October 9-10, exhibit and pre-conference workshop "DOE/RSM Simplified" by me (for details, see http://www.mnasq.org/MNQWorkshopDescriptions.htm)
- National Association of Printing Ink Manufacturers Technical Conference, Ft. Lauderdale, FL, Oct 11, mixture design workshop by Pat Whitcomb (see http://napim.org/TC2006/Tech06Program.htm)
- 50th Fall Technical Conference — Statistics & Quality: 50 Years of Exploration & Discovery, Columbus, OH, October 12-13, exhibit and talk on "A Factorial Design Planning Process" by Shari Kraber and Pat Whitcomb (see http://www.asq.org/cpi/conferences/2006/ and link from there to the program)
- Managing Improvement via Modern Design of Experiments, Stat-Ease workshop, Charlotte, NC, November 14, $349.00 (0.8 CEU's), print form at http://www.statease.com/pubs/managing_improvement_DOE.pdf to register, fax when completed to 612.378.2152
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: Fall schedule offers full DOE curriculum including an Experiment Design Made Easy workshop in Philadelphia
Here's the rundown of Stat-Ease public workshops this Fall season:
- Experiment Design Made Easy ("EDME"), September 26-28, Philadelphia, and again in Minneapolis on October 17-19
- Response Surface Methods for Process Optimization ("RSM"), September 26-28, Minneapolis
- Statistics for Technical Professionals ("STP"), October 4-5, Minneapolis
- Mixture Design for Optimal Formulations ("MIX"), October 24-26, Minneapolis
- Two-Day Crash Course on DOE for Sales & Marketing ("SMDOE2"), November 8-9, Minneapolis
If you are uncertain about which workshop would be best, see http://www.statease.com/training.html for the curriculum in hierarchical form. Click any workshop box for course details. Link from there to online enrollment in the next public class.
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 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. Source of shocking quote for the month — the antagonist, (a leader of a secret organization bent on establishing a perfectly controlled populace) in the paranoid-thriller novel "The Traveler" by John Twelve Hawks.
Acknowledgements to contributors:
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