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Vol: 14 | No: 2 | Mar/Apr '14
Stat-Ease
The DOE FAQ Alert
     
 

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 click here.

To open yet another avenue of communications with fellow DOE and Stat-Ease fans, sign up for The Stat-Ease Professional Network on Linked in. A recent thread features advice for a pharmaceutical scientist “Having problems with outlier detection.”

 
Stats Made Easy Blog

 

 

 

 

 

 

 

 

 

 

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

1:  Software alert: Version 9.0.2 of Design-Expert® software released (free update for licensed users of v9)
2:  FAQ: Are version 8 files compatible with v9 of Design-Expert?
3:  FAQ: How to interpret a quadratic term in a process model
4:  FAQ: What is the best experiment design for reformulating three additives?
5: Webinar alert: “Design-Expert Software: Why Version 9 is Mighty Fine!”
6: Events alert: 2nd Notice for 5th European DOE User Meeting
7: Workshop alert: DOE classes coming to New Jersey and others delivered via Live Web
 
 


PS. Quote for the month: An obvious statistic on birthdays (to go along with my StatsMadeEasy blog on this subject).


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1: Software alert: Version 9.02 of Design-Expert® software released!

Newly-released version 9.0.2 of Design-Expert software is posted at this download site for free trial evaluation.  To update older licensed versions of 9.0, simply download the update from within the program, or download the full installation and reinstall it. The release primarily provides maintenance of existing features.  View the Read Me file for details on this update, installation tips, known ‘bugs,’ change history, and FAQs.

PS. Reminder: If you want to receive notice when an update becomes available, go to Edit on the main menu of your program, select Preferences and, within the default General tab, turn on (if not already on by default) the “Check for updates on program start” option.


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2: FAQ: Are version 8 files compatible with v9 of Design-Expert?

Question from Current User of Design-Expert Software:
“Are files created with version 8 and version 9 compatible with each other?  Thanks."

Answer from the Stat-Ease Support:
“Version 9 can open and save as version 8 files.  In fact, it can save as a version 6 file, and open version 5.  So if you have a 15-year-old DOE file just waiting to be analyzed, you’re in luck!  Check out all the new features of v9 here.  Then put it to the test via a download of the free 45-day trial from this link or press ahead with purchasing the upgrade via this e-commerce site.”


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3: FAQ: How to interpret a quadratic term in a process model

Original question from a Pharmaceutical Scientist:
“My experiment produced the following regression equation for coded units:
Response = + 11.08 + 1.98* A + 4.52* C + 4.16* C2
As per my understanding, the significant factors influencing the response are factors A and C—without any interaction between them.  Then how shall we interpret C2?”

Response from Stat-Ease Consultant Shari Kraber:
“A significant quadratic term means that the response either decreases, as in your case with the positive coefficient on the squared term, or increases in the middle of the design space compared to the corners of the design space.*  As shown below, the 3D surface produced by your Design-Expert software will show a bow (valley or hill) in the surface.

Response surface graph of model with squared term but no interaction

Response surface graph of model with squared term but no interaction

Make use of the numerical optimization tool to find the lowest or highest set of conditions, depending on your goals.”

*P.S.  On the other hand, a model with no squared terms, but only the interaction, for example: Y=f(A,C, AC), produces only a twisted plane, with no bulge upwards or downwards at the center.  See the figure below and compare it to the one above.  The graphs tell the story! –Mark

Response surface graph of model with interaction but no squared term

Response surface graph of model with interaction but no squared term

(Learn more about modeling by attending the two-day computer-intensive workshop Response Surface Methods for Process Optimization.  Click on the title for a complete description.  Link from this page to the course outline and schedule.  Then, if you like, enroll online.)


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4: FAQ: What is the best experiment design for reformulating three additives?

Question from a Paint Chemist:
“It has been found that three additives, A, B, C can improve the impact resistance of polyurethane coating based on initial screening tests.  Now I want to address two questions:

  1. Which additive can give the most property enhancement—can you recommend a single DOE to compare the effects of A, B, C on the coating’s performance?
  2. Is there any synergy among the additives—what is the best approach for assessing non-linear blending effects?”

Answer by Consultant Wayne Adams:
“A mixture design can best provide the answers you seek on additives A, B, and C—the components of interest, any one of which presumably will be allowed to comprise from 0 to 100% of the package.  You can measure them by mass, volume, or moles—anything that makes sense and can be applied to all of the ingredients.  I recommend the simplex-lattice design, which you will find at the top of Design-Expert’s Mixture tab.  The default order of quadratic is a good choice for detecting two-component synergism or antagonism, but if you anticipate more complicated ‘chemistry’ and a few more blends will not break your experimental budget, push up to the special cubic.  Before you go any further, work through the mixture tutorials found here.”

(Learn more about modeling non-linear blending by attending the computer-intensive two-day workshop Mixture Design for Optimal Formulations.  Click on the title for a complete description of this class.  Link from this page to the course outline and schedule.  Then, if you like, enroll online.)


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5: Webinar alert: “Design-Expert Software: Why Version 9 is Mighty Fine!”

In this webinar, repeated three times for your scheduling convenience, I will explain why, from my perspective as an engineer and an ‘experimentalist’, version 9 of Design-Expert (DX9) is mighty fine.  Reserve your Webinar seat now at by clicking one of the links below:

  1. Tuesday, March 4th , 2014 at 5:30 am USA-CT* for Europe, Africa, Middle East and western Asia (others welcome!),
  2. Wednesday, March 5th at 8 pm USA-CT* for eastern Asia and Oceania (others welcome!),
  3. Thursday, March 6th at 11 am USA-CT* for the Americas and Caribbean (others welcome!) .

If this is your first Stat-Ease webinar, please review these suggestions on how to be prepared.  If questions remain, direct them to our Communications Specialist, Karen Dulski, via karen@statease.com.

This one hour presentation will hit on the highlights of what’s new in DX9 and what’s in it for you. For a preview of what’s in store, look here.  I am most enthusiastic about the new release accommodating hard-to-change factors via split-plot design and analysis for factorials—two-level, multilevel categoric (general) and optimal.  I hope you can see me demonstrate this and many other cool new features in this major new release of Design-Expert.  However, if you cannot schedule any of these webinars, take advantage of the recording to be posted after the series of live events.

*(To determine the time in your zone of the world, try using this link.  We are based in Minneapolis, MN, which appears on the city list that you must manipulate to calculate the time correctly.)


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6: Events alert: 2nd Notice for 5th European DOE User Meeting

[2nd Notice] We are pleased to announce the 5th European DOE User Meeting July 10-11 in Cambridge, UK, co-sponsored by PRISMTC.  See further details on the event at their conference site here, including a call for speakers and information about pre-meeting DOE workshops.  The meeting itself and local lodging in particular must be booked early, so you are advised to make your plans as soon as possible.

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

PS.  Do you need a speaker on DOE for a learning session within your company or technical society at regional, national, or even international levels?  If so, contact me.  It may not cost you anything if Stat-Ease has a consultant close by, or if a web conference will be suitable.  However, for presentations involving travel, we appreciate reimbursement for travel expenses.  In any case, it never hurts to ask Stat-Ease for a speaker on this topic.


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7: Workshop alert: DOE classes coming to New Jersey and others delivered via Live Web

All classes listed below will be held at the Stat-Ease training center in Minneapolis, or broadcast from there via “Live Web,”+ unless otherwise noted.  If possible, enroll at least 4 weeks prior to the date so your place can be assured.  Also, take advantage of a $400 discount when you take two complementary workshops that are offered on consecutive days.

+(For those who cannot or prefer not to travel, we deliver select workshops online via GotoWebinar.  If you sign up for one, be prepared for something much more participative than our webinars—these Live Web presentations are workshops so you will be asked to complete a number of case studies using Design-Expert software during class.)

*Take both EDME and RSM in the same week to earn $400 off the combined tuition!

** Take both MIX and MIX2 to earn $400 off the combined tuition!

See this web page for complete schedule and site information on all Stat-Ease workshops open to the public.  To enroll, scroll down to the workshop of your choice and click on it, or call Rachel 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 workshops@statease.com.


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

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.
2021 East Hennepin Avenue, Suite 480
Minneapolis, Minnesota 55413 USA

PS. Quote for the month—An obvious statistic on birthdays (to go along with my StatsMadeEasy blog on this subject):

 
"It is proven that the celebration of birthdays is healthy. Statistics show that those people who celebrate the most birthdays become the oldest.”

—S. den Hartog, Ph D. Thesis University of Groningen.

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, Wayne Adams and Brooks Henderson
—Statistical advisor to Stat-Ease: Dr. Gary Oehlert
Stat-Ease programmers led by Neal Vaughn
—Heidi Hansel Wolfe, Stat-Ease sales and marketing director, Karen Dulski, and all the remaining staff that provide such supreme support!

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DOE FAQ Alert ©2014 Stat-Ease, Inc.
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