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P.S. Quote for the month: Nate Silver on being happy with what our data tells us. (Page down to the end of this e-zine to enjoy the actual quote.) 1: Stat-Ease Academy e-Learning Alert: New web-based class now available for “Easier Experimenting with Factorial Split Plots”
We are pleased to announce the release of a new Stat-Ease Academy class on Easier Experimenting with Factorial Split Plots. This interactive web-based course introduces experimenters to split-plot design and analysis tools that handle hard-to-change (HTC) factors. Learn how you can work around the difficulties of randomizing temperatures and the like that can be varied far more easily by grouping their settings, e.g., low versus high. Naturally taking short cuts like this come at a cost. Do not play with fire—for a modest investment of time (a few hours) and money (follow link above for details) in “Easier Experimenting with Factorial Split Plots” get a handle on these hot tools provided by highly-capable Design-Expert® DOE software. 2: FAQ: How do I set the signal and noise ratio for a given set of data? Original question from a Pharmaceutical Formulation Scientist (R&D):“We are now using and practicing the new Design-Expert software that we purchased. I am facing some difficulty in setting the signal and noise ratio for a given set of data. Please share with me any guidance to set these parameters. Thank you for your support in advance.” Answer from Stat-Ease Consultant Brooks Henderson:“First of all, as you probably know, the signal-to-noise ratio must be set for each of your responses as shown in the screen shot below. Entering signal (difference to detect—delta) and noise (estimated standard deviation—sigma)
In the case illustrated, the response for friability had the lowest signal-to-noise ratio and therefore the least power. Fortunately it just exceeded the recommended minimum of 80%. Therefore this experiment, a minimum-run characterization (resolution V) design, is good to go. If the power had come in lower, then it would have been back to the drawing board for a bigger design or other alternatives that cannot be gone into detail here. (Learn more about signal-to-noise ratio and its effect on power by working through the free “4 Easy Steps to Effective Factorial Design” web-based class listed at the Stat-Ease Academy. Then, to further your education on this topic and much, much, more attend the two-day computer-intensive workshop Experiment Design Made Easy. Click on the title for a description of this class and link from this page to the course outline and schedule. Then, if you like, enroll online.)
Answer from Stat-Ease Consultant Wayne Adams:“We define “verification” as runs done during the experiment, i.e., embedded; whereas “confirmation” comes only after the analysis is complete. Verification runs, a relatively new feature in Design-Expert, are set by you, the user. They are conducted (and recorded) during the experiment, but the data are not used to fit the model. However, their results do show up on diagnostics and the model graphs. If they don’t seem amiss, then you can surmise that your model predicts them reasonably well.
(Learn more about confirmation and verification 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 or contact the Client Specialist at [email protected].)
Original question from a Statistician: The simplex screening designs originally developed by Snee & Marquardt in 1976 lay out 3q+n points, where n is the number of centroids. They are over built for their purpose of fitting a linear model. That’s why we make the axial check blends, constraint plane centroids and overall centroids optional. Going with none of these optional points leaves the q vertices, i.e., 12 points for your case. The optimal design also establishes q points at a minimum (equaling the number of linear coefficients in Scheffè polynomial) with optional additional model points (default zero) lack-of-fit (5) replicate (5) and additional center points—aka centroids (default zero). So in your case Design-Expert recommends 22 runs (=12+5+5). If runs are dear (costly, time-consuming or limited by the supply of materials), I recommend as a compromise going with simplex screening (being built to a template not so mysterious as optimal and thus less daunting to chemists) with the q constraint plane centroids (a bit over the top for those who are geometry-challenged) turned off. In your case of 12 components that would lead to a 29-component design. P.S. FYI see Wayne’s elaboration below. Design-Expert will suggest up to 2q vertices if this many are available from the geometry based on inputted constraints. So for 12 components it defaults to 29 points, including 5 additional centroid reps. Wayne says: (Learn more about screening designs for mixtures by attending the new computer-intensive three-day workshop Mixture and Combined Designs 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.) 5: Info alert: See ASQ TV interview to find out why there’s no need to randomize all your runs Find out why you need not randomize all runs by viewing this interview of me by ASQ TV. (Last notice.) Register now for the 2nd Asian DOE User Meeting in Udaipur, India March 3-5. Udaipur has a romantic and historic past and is known for its culture, palaces and scenic areas. It is often called the “Venice of East” and was voted the best city in the world in 2009 by the Travel + Leisure magazine. Don't miss this opportunity to meet with other Design-Expert users and increase your DOE skills in this popular tourist destination. For all the details, click here. 7: Workshop alert: From New Jersey to Norway You can do no better for quickly advancing your DOE skills than attending a Stat-Ease workshop. In these intensive classes, our expert instructors provide you with a lively and extremely informative series of lectures interspersed by valuable hands-on exercises with one-on-one coaching. Enroll at least 6 weeks prior to the date so your place can be assured—plus get a 10% “early-bird” discount. Also, take advantage of a $400 discount when you take two complementary workshops that are offered on consecutive days.
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 contact the Client Specialist at [email protected] or 612-746-2030. 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.**
Mark J. Anderson, PE, CQE P.S. Quote for the month—Nate Silver on being happy with what our data tells us:
Trademarks: Stat-Ease, Design-Ease, Design-Expert and Statistics Made Easy are registered trademarks of Stat-Ease, Inc. Acknowledgements to contributors: For breaking news from Stat-Ease go to our Twitter feed. DOE FAQ Alert ©2016 Stat-Ease, Inc. |
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