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.
I just returned from Southern California where
I gave a talk to the Society of Industrial Microbiology in Anaheim.
My two teenage daughters came along to visit Disneyland. Coincidentally,
earlier this month The Dallas Morning News reported that the record
for doing Disney is now 10 hours and 40 minutes. It was set by Rich
Vosburgh, an IT guy from Dell Computer. Here's an interesting statistic
from the article: The number of alternative travel schedules for
20 attractions, only half of the number in Disney's Magic Kingdom,
exceeds 50 million billion combinations, or six times the number
of grains of sand on Earth! To learn how Vosburgh selected the optimal
route, copy and paste this web site path into your Internet browser: www.mickeynews.com/News/DisplayPressRelease.asp_Q_id_E_744Day,
or click on this link— http://makeashorterlink.com/?Y2FC643F8.
Here's what I cover in the body text of this
DOE FAQ Alert (topics that delve into statistical detail are designated "Expert"):
The models for multicategoricals get very messy, especially with more than one factor, so you'd best not look at them but rather make use of the effects plots, which show the predicted means and least significant differences (LSD).
Stat-Ease consultant Shari Kraber contributed this explanation:
Stat-Ease consultant Pat Whitcomb provides this
detail in training materials* on how Design-Expert models the main
effect from a categorical factor:
*(Learn more about factorials with categoricals by attending the three-day computer-intensive workshop "Experiment Design Made Easy." See http://www.statease.com/clas_edme.html for a course description. Link from this page to the course outline and schedule. Then, if you like, enroll online.)
Click the following link to view an article titled "Solving Process Issues at an ASIC Fab using Design of Experiments" published in the July 2004 issue of MICRO Magazine: http://www.micromagazine.com/archive/04/07/clarke.html. See how author Carl Clarke, of AMI Semiconductor, solved two perplexing wafer production mysteries using design of experiments, thus saving the company $180,000 a year.
To view an article from Paint & Coatings Industry Magazine on mixture design titled "How to Bake the Perfect Cake", click http://makeashorterlink.com/?D275128F8. The author, Rick Roesler, worked with the three Principals of Stat-Ease—Pat Whitcomb, Tryg Helseth and me—at General Mills Chemical Division in the 1970's. These were formative years for all four of us in the field of DOE and in particular, mixture design.*
*(To master these powerful tools of DOE, attend our "Mixture Design for Optimal Formulation" workshop. For a description, see http://www.statease.com/clas_mix.html. Link from this page to the course outline and schedule. You can enroll online by linking to the Stat-Ease e-commerce page for workshops.)
I received many comments about my youngest daughter's taste test on colas (see http://www.statease.com/news/news0405.pdf). Here's an inquiry that inspired me to detail more experiments that might be fun for adults and children.
See 'Katie's Favorites' and many other fun experiments in a newly revised list called "DOE It Yourself" that's posted at http://www.statease.com/pubs/doe-self.pdf.
Reminder: If you make it to the 2004 Joint Statistical Meetings (JSM) in Toronto, Canada in August, stop and visit Stat-Ease at booth #405. Also, sign up for the JSM RoundTable Discussion on Wednesday, August 11th on "Design of Experiments Trials and Tribulations." Stat-Ease consultant Shari Kraber will be the moderator. She says "Participate in a lively discussion of the trials and tribulations of planning and running designed experiments. Plan to share your experiences and learn from the experiences of others. Discuss the most common pitfalls that experimenters encounter and learn how to avoid them. Explore problems with fractional factorials, mixtures, missing data, pass/fail data, etc."
Click http://www.statease.com/events.html for a list of appearances by Stat-Ease professionals. We hope to see you sometime in the near future!
Stat-Ease will present "Experiment Design Made Easy" on August 17-19 in Philadelphia. For those of you on the East Coast of the USA, this is a great opportunity to learn DOE in your own backyard.
See http://www.statease.com/clas_pub.html for schedule and site information on this and all other 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.
Mark J. Anderson, PE, CQE
PS. Quote for the month—Provocative statements from two new books on statistics:
"Using fancy tools
like neural nets without understanding statistics
is like doing brain surgery before knowing how to use a band-aid."
"No single correct,
end-all and be-all answer exists. Some people say that's what they
love about statistics, and some say that's what they hate about
Acknowledgements to contributors:
DOE FAQ Alert—Copyright 2004
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