Issue: Volume 6, Number 3
Date: March 2006
From: Mark J. Anderson, Stat-Ease, Inc. (http://www.statease.com)

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 http://www.statease.com/doealertreg.html. If this newsletter prompts you to ask your own questions about DOE, please address them via mail to:[email protected].

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Here's an appetizer to get this Alert off to a good start: See our new blog http://statsmadeeasy.net for lots of fun chat with a statistical/scientific/engineering bent. My profession of chemical engineers often refer to ourselves as 'comical en-grin-eers,' so be forewarned that the submissions to Stats Made Easy blog from me may be somewhat frivolous. Contributions from other statisticians at Stat-Ease, while less frequent, will likely be far more weighty. Feel free to comment on Stats Made Easy blogs. You may do this without entering your e-mail address. However, all entries are subject to my moderation of content considered abusive, illegal, defamatory, libelous, indecent, obscene, offensive, or threatening in any way. Many of you may make use of RSS (Really Simple Syndication) readers, which track and aggregate updates from your favorite web sites. As a user of Microsoft Outlook, I recommend RSS Popper freeware, which loads up quickly, is very intuitive to use and not too intrusive. You can download it from http://rsspopper.net/2004/10/home.html. Then right-click on Stats Made Easy link to "Site Feed" and choose "Subscribe in RSS Popper" to be notified of new blogs from me or our statistical consultants at Stat-Ease. FYI, here are the select few blogs that divert my attention:
—Politically Incorrect Statistics
http://www.picstat.blogspot.com//
—Curious Cat Science and Engineering
http://engineering.curiouscatblog.net/.

Here's what I cover in the body text of this DOE FAQ Alert (topics that delve into statistical detail are designated "Expert"):

1. FAQ: Why a p-value is not provided for variance from blocks
2. Info Alert: Review of DOE software favors Design-Expert®
3. Reader response: Getting the edge on Occam's Razor
4. Events alert: First European DOE User Meeting
5. Workshop alert: Crash Course on DOE for Sales & Marketing

PS. Quote for the month: Hunting for effects of practical importance that are statistically significant.

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1. FAQ: Why a p-value is not provided for variance from blocks

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PLEASE DO NOT SEND ME REQUESTS TO SUBSCRIBE OR UNSUBSCRIBE—FOLLOW THE INSTRUCTIONS AT THE END OF THIS MESSAGE.

Sincerely,

Mark

Mark J. Anderson, PE, CQE
Principal, Stat-Ease, Inc. (http://www.statease.com)
2021 East Hennepin Avenue, Suite 480
Minneapolis, Minnesota 55413 USA

PS. Quote for the month—Hunting for effects of practical importance that are statistically significant:

"The effects plot flushes the birds and the stats shoot them down."

—Peter Fortini, Principal Statistician, Wyeth Biopharma, Andover, Maryland

This is a work in progress that came up as an ad lib during a teleconference on analysis of two-level factorials for ruggedness testing*—in particular the value of producing a half-normal plot of effects. Here's a thread of conversation I had with Peter afterwards. I said,"Peter, so far as I am concerned, you scored a direct hit by saying this. Is this something you made up on the spot, or did you hear it from someone else?" He said, "Actually, I just made it up on the spot—the recent story about our vice president crossed my mind at the moment. I think what I said or meant to say is 'the effects plot flushes the birds and the statistical test shoots at them.' The alternative wording is suggested because "shoot them down" has the implication that you succeed. A detail that is key to me is that when you shoot, it's a matter of chance whether you get a hit or miss (or bag your hunting companion! Now that you point it out, it really is a pretty good metaphor. If you hadn't captured it, I'd have forgotten, so this is more yours than mine." Do you readers have any suggestions for refining Peter's hunting metaphor?
—Mark

PS. Wayne Adams adds this comment: "The half-normal plot always makes sure the birds flush out front, so you are less likely to pick-off the wrong target!"

*(See December Stat-Teaser cover-page article "Struggle for Power vs. Resolution vs. Simplicity in an ASTM Standard" at http://www.statease.com/news/news0512.pdf.)

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
—Fellow Stat-Ease consultants Pat Whitcomb, Shari Kraber and Wayne Adams (see http://www.statease.com/consult.html for resumes)
—Statistical advisor to Stat-Ease: Dr. Gary Oehlert (http://www.statease.com/garyoehl.html)
—Stat-Ease programmers, especially Tryg Helseth and Neal Vaughn (http://www.statease.com/pgmstaff.html)
—Heidi Hansel, Stat-Ease marketing director, and all the remaining staff

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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 (see above)

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