Issue: Volume 9, Number 4
Date: April 2009
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, see below.

==> Tip: Get immediate answers to questions about DOE via the Search feature on the main menu of the Stat-Ease® web site. This not only pores over previous alerts, but also the wealth of technical publications posted throughout the 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 one):

—Phenology — the study of the timing of natural events
—Nearly 90% of cardiologist-approved heart therapies are not supported by high-quality scientific testing
—Basketball players fail to cash in on free throws
—Detecting outliers graphically**

**(Features an amusing cartoon)

* Need a feed from StatsMadeEasy to Microsoft's Outlook? See
** (See the comment to this blog and follow its link to an amazing collection of stats and graphs on record temps across the USA)

Also, Stat-Ease offers an interactive web site — its Support Forum for Experiment Design at Whereas this monthly e-zine shares one-on-one communications with Stat-Ease StatHelp, anyone can post questions and answers to the Forum, which is open for everyone to see (with moderation). Check it out and weigh in!

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

1. Newsletter Alert: March issue of the Stat-Teaser features science fair project that provides enlightenment on outliers
2. Educational Alert: Free primer on mixture design posted
3. FAQ:What if I put all the low levels of a factor in one block and all the high levels in the other block?
4. Webinar Alert (2nd): "DOE — What's In It for Me" — an executive summary on the power of matrix-based multifactor testing
5. Events Alert: Best Practices to Plan/Analyze a Verification DOE (2nd Notice)
6. Workshop Alert: See when and where to learn about DOE

P.S. Quote for the month:Deming's skepticism about how things change over time, thus unraveling those without profound knowledge of their process.


1. Newsletter Alert: March issue of the Stat-Teaser features science fair project that provides enlightenment on outliers and also a free "Primer on Mixture Design for Optimal Formulation"

Many of you 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 only view of the March issue at It features an article by me on how a "Science Fair Project Provides Education on Detecting Outliers." If you're up for a challenge, do not turn the first page until you either try finding the outlier yourself, or at least make an educated guess by looking at the factor levels on each run.

Thank you for reading our Stat-Teaser newsletter. If you do get the hard copy, but find it just as convenient to read what we post to the Internet, consider contacting us to be taken off our mailing list, thus conserving resources. However, we do appreciate you passing around hard copies of the Stat-Teaser, so do not feel obliged to forego this.


2. Educational Alert: Free primer on mixture design posted

See the latest Stat-Teaser (link above) for what inspired me to offer up a free "Primer on Mixture Design for Optimal Formulation" co-authored by me and Pat Whitcomb. Here is the direct link: Feel free to download it for your education on this powerful tool in the DOE kit. All I ask is that if you like what you see and become convinced that this primer will be valuable for your colleagues, please send them the link.


3. FAQ: What if I put all the low levels of a factor in one block and all the high levels in the other block?

-----Original Question-----
From: Nutritional scientist
"I've attached a screening DOE where I have two blocks of runs done on two separate days. To reduce set-up time somewhat, I'm considering the idea of putting all the low levels for my most problematic factor, H, in block 1 and the high levels in block 2. Will this DOE capture any significant effect for factor H, or will H's potential effect be blocked out? If this causes a problem, I will just have to put in longer hours each of the two days."

That is not a good idea! The H effect will be lost (completely confounded) to the block estimate. Since you do not rule out investing a few more hours in this experiment, I urge you to run factor H at randomized levels within each block as specified by your DOE program (Design-Expert(R) software). Consider this to be an investment that will surely pay dividends in providing an effective screening on factor H.

PS. For a nicely-illustrated primer on blocking, see this write-up in the NIST/SEMATECH e-Handbook of Statistical Methods:

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


4. Webinar alert (2nd): "DOE — What's In It for Me" — an executive summary on the power of matrix-based multifactor testing

You are invited to attend a free web conference by Stat-Ease Consultant Wayne Adams on "DOE — What's In It for Me." This free conference, which Wayne will keep at a managerial level statistically, will be broadcast on Wednesday, May 27 at 2 PM USA Central Time* (CT). He will repeat his webinar on Thursday, May 28 at 8 AM. It is aimed at those who need convincing on how design of experiments harnesses the power of matrix-based multifactor testing. Ideally, after seeing what DOE can do, it will be favored over the old-fashioned one-factor-at-a-time (OFAT) method.

Stat-Ease webinars vary somewhat in length depending on the presenter and the particular session — mainly due to breaks for questions: Plan for 45 minutes to 1.5 hours, with 1 hour being the target median. When developing these one-hour educational sessions, our presenters often draw valuable material from Stat-Ease DOE workshops. Attendance may be limited, so sign up soon by contacting our Communications Specialist, Karen, via 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).

*(To determine the time in your zone of the world, try using this link: Note that we are based in Minneapolis, which appears on the city list that you must manipulate to calculate the time correctly. It seems that figuring out the clock on international communications is even more complicated than statistics! Good luck!)


5. Events Alert: Best Practices to Plan/Analyze a Verification DOE (2nd Notice)

Stat-Ease Consultant Shari Kraber will present "Best Practices to Plan/Analyze a Verification DOE" on Tuesday, May 19 in a session sponsored by the Statistics Division of the American Society of Quality (ASQ) for the World Conference on Quality Improvement (WCQI) in Minneapolis. For details on WCQI, see

As an added bonus for those of you who attend WCQI, Stat-Ease Consultant Pat Whitcomb will speak at an Open Council Meeting of ASQ's Chemical & Process Industries Division (CPID) on "Sizing Mixture Designs" at 5 PM on Monday, May 18.

At the 2009 Quality & Productivity Research Conference (QPRC) in Yorktown, NY on June 3-5, I will present "Dual Response Surface Methods (RSM) to Make Processes More Robust." This is one of three talks in the "New developments in Design of Experiments" invited session organized by Douglas C. Montgomery of Arizona State University. For all the details on QPRC, see

Click for a list of upcoming 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

Seats are filling fast for the following DOE classes. If possible, enroll at least 4 weeks prior to the date so your place can be assured. However, do not hesitate to ask whether seats remain on classes that are fast approaching!

—> Experiment Design Made Easy (EDME)
(Detailed at
> April 28-30 (Minneapolis, MN)
> June 9-11 (Minneapolis)

—> Mixture Design for Optimal Formulations (MIX)
> April April 21-23 (Minneapolis)
> June 23-25 (Edison, NJ)

—> Response Surface Methods for Process Optimization (RSM)
> July 7-9 (Minneapolis)

—> DOE for DFSS: Variation by Design (DDFSS)
> May 5-6 (Minneapolis)

—> Designed Experiments for Life Sciences (DELS)
> June 8-9* (Cambridge, MA) *Tentative
> July 28-29 (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. Quote for the month —Deming's skepticism about how things change over time, thus unraveling those without profound knowledge of their process:

"Unfortunately, future experiments (future trials, tomorrow’s production) will be affected by environmental conditions different from those that affect this experiment. It is only by knowledge of the subject matter, possibly aided by further experiments, to cover a wider range of conditions, that one may decide, with a risk of being wrong, whether the environmental conditions of the future will be near enough the same as those of today to permit the use of results in hand."

—Dr. W Edwards Deming

Trademarks: Stat-Ease, Design-Ease, Design-Expert and Statistics Made Easy 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, led by Neal Vaughn and Tryg Helseth (
—Heidi Hansel Wolfe, Stat-Ease sales and marketing director, and all the remaining staff that provide such supreme support!


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#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, #8-3 Mar 08, #8-4 Apr 08, #8-5 May 08, #8-6 June 08, #8-7 July 08, #8-8 Aug 08, #8-9 Sep 08, #8-10 Oct 08, #8-11 Nov 08, #8-12 Dec 08, #9-01 Jan 09, #9-02 Feb 09, #9-03 Mar 09, #9-04 Apr 09 (see above)

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