Happy New Year!
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 start. On December 10, Sharon Begley, who authors the "Science Journal" column in the "Wall Street Journal," discussed a controversy over the effectiveness of discovery learning." She cites research by David Klahr of Carnegie Mellon University that debunks this idea that it's best for children to find things out for themselves rather than being lectured. Ironically, Klahr's study contrasted instructional approaches for teaching how experiments must change only one factor at a time (OFAT). The elementary school subjects studied how balls rolled down a ramp. They could vary several factors:
A. Type of ball: golf ball versus rubber ball
B. Surface of ramp: smooth versus rough
C. Angle of ramp: steep versus shallow
D. Width of ramp: short versus long
See http://www.psy.cmu.edu/faculty/klahr/KlahrNigam.2-col.pdf for the report. Also, check out another study by Klahr where he concludes that elementary school students learn OFAT just as effectively from computer simulations as from physical experiments http://www.psy.cmu.edu/faculty/klahr/Triona&Klahr.pdf. This research is all very interesting except for it being so intent on teaching OFAT. :(
Here's what I cover in the body text of this DOE FAQ Alert (topics that delve into statistical detail are designated "Expert"):
1. Newsletter alert: Link to the December Stat-Teaser featuring a DOE dedicated to making grilled hot dogs most deliciously
2. Reader contributions: Educational DOE's on popcorn and copters
3. Reader reply: Space weather and the price of wheat
4. Info alert: Newly published book--"RSM Simplified"
5. Events alert: Six Sigma Conference--exhibit and talk
6. Workshop alert: See when and where to learn about DOE
PS. Quote for the month: What Piaget, an expert on child development, says about discovery learning.
Many of you by now may have received a printed copy of the latest Stat-Teaser, but others, by choice or because you reside outside of North America, will get your first look at the December issue at http://www.statease.com/news/news0412.pdf.
The feature article, "University of Minnesota Duluth [UMD] Dogs," by Bill Pederson, details an experiment done by students on how best to grill various types of hot dogs (beef, pork and turkey). Bill, a professor in UMD's department of mechanical and industrial engineering, addresses concerns about subjective measurements--in this case: taste.
Other stories in the Stat-Teaser provide:
- Enlightenment on three-factor interactions from Pat Whitcomb*
- New pricing for network licenses of Stat-Ease software.
*(To learn more about how to detect and interpret interactions, attend 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.)
"My class performed a factorial design on four brands of popcorn: Orville Redenbacher, Act II, Pop-Secret and a local generic. On the first day we made "home" type and on the second day the "movie" style, with replicate runs of each. The undergraduate students thought these experiments were a blast! The tasters
included several members of our football team. They applied five-point rating scales to:
—flavor (1: crunchy, flaky, yet light; versus 5: chewy, dense)
—texture (1: nicely salted; versus 5: bitter charcoal)
—overall liking (1: yummy; versus 5: yucky).
One of my students presented the results as a poster session for the American Chemical Society (ACS) undergraduate meeting of the Louis Stokes Alliance for Minority Participation Conference. Another of my students will present the popcorn DOE to the undergraduate seminar at the math department here at BSU. I consider the Stat-Ease software a great learning tool. Thanks for all your help.
I think that writing up the popcorn experiment for an introduction to factorial design would be a good idea,
particularly if it provided specific instruction for teachers to use at a lower-level college course or perhaps high-school level. Have you written this up for a journal?"
Patti, I am glad your students had an enjoyable, educational experience with this exercise and fed the football players in the process. I did something similar to establish what brand of popcorn should be bought for consumption at Stat-Ease headquarters.*
I agree that it would be good for someone to publish instructions on experimenting with popcorn. I'd be happy to provide help to you or anyone else who wants to take this on as a project. My advice is that such an article start with a warning: Caution--Popcorn is flammable! In my office I have a jar containing a lump of burnt popcorn from my 1992 experiment done with my (then) 5th-grade son Hank for his school science project.** We had quite an exciting moment in the Anderson household when the butter flamed
out of a bag of popcorn that got cooked too long. It literally melted a hole in the side of the microwave! I keep the charred remains around as a reminder to be careful when testing factors at their extremes. For screening purposes, it's good to be bold in setting levels to generate discernible effects, but not if it
burns down the building. If the limits are not well established, do some pre-experimentation for range-finding purposes (and keep your finger poised over the off button).
From: Koos Jorritsma, Senior Lecturer, Bioprocess Technology, Noordelijke Hogeschool Leeuwarden (NHL), University of Professional Education, Leeuwarden, Netherlands (NL)
"I always enjoy reading your FAQ and newsletters. This Fall I completed my course in DOE with my chemical engineering students. As a final test I asked them to find the optimal paper helicopter design that I found as a result of reading your article.* In a 1.5 hour period they had to start from scratch, design tests, build their planes, test fly them and analyze results. In the last 5 minutes they had the final challenge to use their optimal plane: it needed to descend as slow as possible and end up as close as possible to the target. Test flights from the second floor, final test from the third. Both students and teacher enjoyed the event. Thanks again for your publications. I hope to enjoy them much longer."
I am pleased that my article inspired you to do this experiment. I like your pictures very much! It's obvious from your photo site that the assignment was done around Halloween. It just occurred to me that a scary costume would be to dress up like a professor of statistics. I've found that just the mention of this subject creates a noticeably adverse reaction from even the most highly-educated technical professionals. However, by letting students play around with helicopters and the like, the fear of statistics
From: Eric Kvaalen, Paris
"In your latest DOE FAQ Alert you mention space weather.* The other day I came across something interesting--a correlation between the sunspots and the price of wheat in the US during the 20th century. It was found that the prices at the sunspot maxima minus the prices at the preceding sunspot minima (over 8 cycles) were usually positive (6 out of the 8) and the average difference was statistically significantly above zero. The authors write "A possible explanation of this surprising result is the compact localization of wheat production in the USA (especially, durum and spring wheat). For example, about 70% of all durum in the USA is produced in a part of North Dakota. I didn't realize my native state was so important! Here's the link to the New Scientist article I saw that led me to this research: http://www.newscientist.com/news/news.jsp?id=ns99996680."
I see some real possibilities for making bread here (pun intended), especially for commodity traders. Could space weather add a long-term component to the variable behavior of folks up our way, which in the short-term are aberrantly affected by earth weather--the long, dark winter as immortalized in the Coen
brothers' movie "Fargo"? For some borderline theories on this, see http://www.borderlands.com/sun/sunspots.htm.
*December 2004 issue at http://www.statease.com/news/faqalert4-12.html.
Yes, I am making another shameless plug for "RSM Simplified, Optimizing Processes Using Response Surface Methods for Design of Experiments" (Anderson and Whitcomb, Productivity, Inc., New York, NY, copyright 2005). "RSM Simplified" makes an ideal companion to the previous book co-authored by Pat and me: "DOE Simplified." The two books provide a full range of tools for breakthrough and optimization of processes--all presented in a non-academic manner (in other words: fun to read!). Whereas the first book in the series comes with Design-Ease® software, the new "RSM Simplified" book provides the more advanced Design-Expert® program. Both programs are fully-functional, but limited to 180 days of use. The Design-Expert software for "RSM Simplified" is actually a beta release of version 7, which offers an impressive upgrade in designs, tools for analysis, and graphics. Thus, by buying this new book you get a sneak preview of the new software, expected to become commercial in mid to late 2005, depending on how long it takes for beta testing.
For more details on "RSM Simplified" and how it can be purchased, see http://www.statease.com/rsm_simplified.html.
(Learn more about RSM 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.)
I will be exhibiting Stat-Ease software and giving a talk at the American Society of Quality (ASQ) 2005 Six Sigma Conference in Palm Springs, CA on February 7-8. For details on the conference, see http://www.asq.org/ed/conferences/sixsigma/2005/. My presentation will be on "Cost-Effective and Information-Efficient Robust Design for Optimizing Processes."
Also, see Stat-Ease software exhbited by the DOES Institute at the AIAA Aerospace Sciences Meeting in Reno, NV on January 10-13. See http://www.aiaa.org/content.cfm?pageid=230&lumeetingid=666.
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!
6. 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 month: What Piaget, expert on child development, says about discovery learning:
"Each time one prematurely teaches a child something he could have discovered himself the child is kept from understanding it completely."
--Jean Piaget, 1896–1980 http://www.piaget.org/aboutPiaget.html
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DOE FAQ Alert—Copyright 2005
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