Issue: Volume 8, Number 2
Date: February 2008
From: Mark J. Anderson, Stat-Ease, Inc., Statistics Made Easy® Blog

Dear Experimenter,

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 If this newsletter prompts you to ask your own questions about DOE, please address them via mail

For an assortment of appetizers to get this Alert off to a good start, see these new blogs at (beginning with the most recent on down):
— The smoking statistician
— The real reason why results always vary?
— Fun fling with discs in sunny Southern California
— "Random" banished by Lake Superior State’s grammar guardians

Topics in the body text of this DOE FAQ Alert are headlined below (the "Expert" ones, if any, delve into statistical details).

1. Released: Version 7.1.4 of Design-Expert(R) software
2. FAQ: What if actual factor levels do not go as planned?
3. FAQ: Time ran out before all the runs could be completed in one of my experimental blocks: Now what happens?
4. Book Alert: DOE Simplified, Second Edition, finds favor from Journal of Quality Technology reviewer
5. Info Alert: Teaching DOE to engineering students
6. Webinar Alert: Learn how to accomplish multiple response optimization with Design-Expert
7. Event Alert: Lean Six Sigma Conference, Euro DOE Meeting
8. Workshop Alert:Experiment Design Made Easy in Philadelphia

PS. Quote for the month: Cynical view of statistical analysis — warning, this is really wicked! (Page through to the end of this e-mail to enjoy the actual quote.)


1. Released: Version 7.1.4 of Design-Expert software

Version 7.1.4 of Design-Expert® ("DX") software is now posted at for a free, fully-functional 45-day trial.* This web site also provides free patches to update older, licensed, versions of 7.1. The new release primarily addresses maintenance issues. View the ReadMe file for installation tips,** known 'bugs,' change history, and FAQs.

*If you cannot download the software due to organizational security, consider taking the "online tour" to see how easy Stat-Ease software makes the design and analysis of experiments, specifically two-level factorials for discovery or verification. If you need something to brighten up your day, click the "spinning graph" link to see the newly posted video of a colorful 3D response surface generated and rotated by Design-Expert.

**Network administrators are advised of some important changes that must be understood before updating to V7.1.4.


2. FAQ: What if actual factor levels do not go as planned?

-----Original Message-----
From: Chicago
"I have a four-factor design. We originally set up the moisture variable to have three levels (2.1, 2.5, 2.9) in Design-Expert. However the actual values have some variation (lowest is 1.73, highest is 3.11). Should I use the actual values? If so, do I need to reset the high-low range in DX7? Thanks for your help!"

Answer (from Stat-Ease Consultant Pat Whitcomb):
"If the actual values are more meaningful (e.g. better represent the factor) then use them. To keep the coding correct (-1 the lowest and +1 the highest), right click on the factor heading and enter the low (1.73) and high (3.11) values. This will change all the values in that factor column. Now type the actual factor level in for each run. Good luck with your DOE!"

This was one of the first FAQs after inaugurating the Alert at the beginning of this decade (and century and millennium!): See the April 2001 issue, FAQ #1, on "Botched runs in fractional two-level factorial designs - When to enter actual versus planned factor level" posted at
- Mark


3. FAQ: Time ran out before all the runs could be completed in one of my experimental blocks: Now what happens?

-----Original Message-----
From: Cleveland
"What are the implications in both the experimental file modification and analysis of the results when you intend to block an experiment in two blocks (i.e. two different days) and can not complete the block as required? In other words, not finishing all the lots in the block in the first day."

Answer (from Stat-Ease Consultant Shari Kraber):
"Due to the runs being randomized within blocks, it is not possible to know the real effect of not completing a block in advance - it will depend on the specific changes. When this happens, the runs should be reassigned to the correct blocks and then the new aliasing pattern should be checked. It will likely (although not always) become partially aliased. If the alias coefficients are quite small and/or are with high-order interactions, then even this shouldn't pose a real problem. With the new lack of orthogonality, all effects will no longer be estimated with the same precision, but generally they won't be that different. Whenever things like this go wrong, the analysis will no longer be perfect, but it will likely still be very
useful. The best that can be done is to complete the analysis, make sure the results make sense from a subject-matter standpoint, and confirm the results with confirmation runs."

(Learn more about blocking by attending the three-day computer-intensive workshop "Experiment Design Made Easy." See for a description of this class and then link from this page to the course outline and schedule. Then, if you like, enroll online.)


4. Book Alert: DOE Simplified, Second Edition, finds favor from Journal of Quality Technology reviewer

ASQ featured a review of DOE Simplified, 2nd Ed, in their January issue of Journal of Quality Technology (JQT). Here's the final words from the reviewer, Willis A. Jensen of W. L. Gore: "It is very challenging to come up with a short, readable book on DOE for the beginner that covers enough to be useful but not too much to be overwhelming and the authors do succeed in that regard. In spite of some minor shortcomings, this book would be most helpful to the self-guided beginner or to someone who wants a quick refresher of the basic concepts of DOE."

(For more details on DOE Simplified, including a sample chapter, see


5. Info Alert: Teaching DOE to engineering students

David R. Mills, Instructor & Manager of Process Engineering Laboratories for the Department of Chemical Engineering at Auburn University allowed us to share his presentation on "Combining Computer-Aided Statistical Design of Experiments with Traditional Design of Experiments to Meet EC2000 Criteria." See this at He said "I'd be honored to have the paper posted. As indicated in the paper, the software works very well for us and it is always a pleasure doing business with you nice folks." Thanks Dave! It would be great if more engineering schools taught the principles of statistical design and analysis of experiments, even though that would mean fewer technical professionals needing remedial short-courses (where Stat-Ease comes to the rescue).


6. Webinar alert: Learn how to accomplish multiple response optimization with Design-Expert

You are invited to attend a free web conference by Stat-Ease on "Multiple response optimization with Design-Expert" at 8 AM Central USA Time on Tuesday, April 1. It will be presented again at 12 PM (noon) on Wednesday, April 2. Here is the abstract from the talk's author, Consultant Shari Kraber:

"The optimization module in Design-Expert searches for combinations of factor levels that simultaneously satisfy the requirements placed on each of the responses and factors. Discover how to get the most out of the optimization module in order to find the "sweet spot" for your product or an operating window for your process. Learn how to fine-tune your search by adding weights and importance settings to your basic criteria. A case study will be used to illustrate all the features of Design-Expert's optimization module."

Attendance may be limited for one or both of these two one-hour webinar sessions. Contact our Communications Specialist, Karen Dulski, via to sign up. If you can be accommodated, she will send you the link for the WebConnect and dial-in for ConferenceNow voice via telephone. Toll-free access extends worldwide, but not to all countries. The Powerpoint slides from prior webinars are posted at Over 100 attendees enrolled for the most recent presentation on "10 Ways to Mess Up an Experiment & 8 Ways to Clean It Up." This basic-level presentation provided practical advice for actual experimenters. The prior presentations by Consultant Pat Whitcomb provided more advanced statistical details on sizing designs for process screening and mixture optimization. The upcoming webinar by Shari Kraber will be aimed at an intermediate level of expertise on DOE.


7. Events Alert: Lean Six Sigma Conference, Euro DOE Meeting

At the 2008 ASQ Lean Six Sigma Conference, held February 11-12 in Phoenix, Stat-Ease Consultant Pat Whitcomb will explain "How to Plan and Analyze a Verification DOE." This "extremely overwhelming" positively reviewed presentation is detailed at See for information on the conference and registration. Pat will be available for discussion at the Stat-Ease exhibit.

The Second European DOE User Meeting will be held March 10-12 in Berlin, Germany. Come to increase your understanding of design of experiments (DOE) techniques, learn of successful real-life applications of DOE, and also attend presentations specific to Stat-Ease software and its features. For more information, see

Click for a list of upcoming appearances by Stat-Ease professionals. We hope to see you sometime in the near future!


8. Workshop Alert: Experiment Design Made Easy in Philadelphia

Seats are filling fast for the following DOE classes:

—> Experiment Design Made Easy (EDME)
(Detailed at
> March 4-6 (Philadelphia, PA)

—> Mixture Design for Optimal Formulations (MIX)
> April 8-10 (Minneapolis, Minnesota)

—> Response Surface Methods for Process Optimization (RSM)
> February 26-28 (Minneapolis)

—> DOE for DFSS: Variation by Design (DDFSS)
> March 11-12 (Minneapolis)

See for complete 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 Elicia at 612.746.2038. 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.*

*Once you achieve a critical mass of about 6 students, it becomes very economical to sponsor a private workshop, which is most convenient and effective for your staff. For a quote, e-mail


I hope you learned something from this issue. Address your general questions and comments to me at:



Mark J. Anderson, PE, CQE
Principal, Stat-Ease, Inc. (
2021 East Hennepin Avenue, Suite 480
Minneapolis, Minnesota 55413 USA

PS. Quotes for the month—Cynical view of statistical analysis—warning, this is really wicked!:

"Statistical Analysis: Mysterious, sometimes bizarre,
manipulations performed upon the collected data of an experiment
in order to obscure the fact that the results have no
generalizable meaning for humanity. Commonly, computers are used,
lending an additional aura of unreality to the proceedings.

Trademarks: Design-Ease, Design-Expert and Stat-Ease are registered trademarks of Stat-Ease, Inc.

Acknowledgements to contributors:
—Students of Stat-Ease training and users of Stat-Ease software
—Stat-Ease consultants Pat Whitcomb, Shari Kraber and Wayne Adams (see for resumes)
—Statistical advisor to Stat-Ease: Dr. Gary Oehlert (
—Stat-Ease programmers, especially Tryg Helseth and Neal Vaughn (
—Heidi Hansel, Stat-Ease marketing director, and all the remaining staff


Interested in previous FAQ DOE Alert e-mail newsletters?
To view a past issue, choose it below.

#1 Mar 01, #2 Apr 01, #3 May 01, #4 Jun 01, #5 Jul 01 , #6 Aug 01, #7 Sep 01, #8 Oct 01, #9 Nov 01, #10 Dec 01, #2-1 Jan 02, #2-2 Feb 02, #2-3 Mar 02, #2-4 Apr 02, #2-5 May 02, #2-6 Jun 02, #2-7 Jul 02, #2-8 Aug 02, #2-9 Sep 02, #2-10 Oct 02, #2-11 Nov 02, #2-12 Dec 02, #3-1 Jan 03, #3-2 Feb 03, #3-3 Mar 03, #3-4 Apr 03, #3-5 May 03, #3-6 Jun 03, #3-7 Jul 03, #3-8 Aug 03, #3-9 Sep 03 #3-10 Oct 03, #3-11 Nov 03, #3-12 Dec 03, #4-1 Jan 04, #4-2 Feb 04, #4-3 Mar 04, #4-4 Apr 04, #4-5 May 04, #4-6 Jun 04, #4-7 Jul 04, #4-8 Aug 04, #4-9 Sep 04, #4-10 Oct 04, #4-11 Nov 04, #4-12 Dec 04, #5-1 Jan 05, #5-2 Feb 05, #5-3 Mar 05, #5-4 Apr 05, #5-5 May 05, #5-6 Jun 05, #5-7 Jul 05, #5-8 Aug 05, #5-9 Sep 05, #5-10 Oct 05, #5-11 Nov 05, #5-12 Dec 05, #6-01 Jan 06, #6-02 Feb 06, #6-03 Mar 06, #6-4 Apr 06, #6-5 May 06, #6-6 Jun 06, #6-7 Jul 06, #6-8 Aug 06, #6-9 Sep 06, #6-10 Oct 06, #6-11 Nov 06, #6-12 Dec 06, #7-1 Jan 07, #7-2 Feb 07, #7-3 Mar 07, #7-4 Apr 07, #7-5 May 07, #7-6 Jun 07, #7-7 Jul 07, #7-8 Aug 07, #7-9 Sep 07, #7-10 Oct 07, #7-11 Nov 07, #7-12 Dec 07, #8-1 Jan 08, #8-2 Feb 08 (see above)

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