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Design of Experiments

How to apply the statistical method called Design of Experiments (DOE) for quality improvement and research.

NOTE: This story will reveal how easy it can be to optimize settings using the statistical method called Design of Experiments, but it won't provide easy answers for making your own office coffee any better. After her team’s ultimatum about the wretched office coffee, Jill used the design-of-experiments (DOE) tool in Minitab 17’s Assistant to design and analyze a screening study. Jill now knew... Continue Reading
Everyone loves a Pareto chart. That is, everyone who knows that Pareto charts are a type of bar chart ordered by bar size to help you to determine which bars comprise the vital few that you care about and which are the trivial many that you don't care about. Pareto charts are a great tool for communicating where the largest gains can be made as you focus your improvement efforts. Since I love... Continue Reading

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In Blind Wine Part I, we introduced our experimental setup, which included some survey questions asked ahead of time of each participant. The four questions asked were: On a scale of 1 to 10, how would you rate your knowledge of wine? How much would you typically spend on a bottle of wine in a store? How many different types of wine (merlot, riesling, cabernet, etc.) would you buy regularly (not as... Continue Reading
Already relaxed on his first day in Napa, Brutus and his wife Suzy decide to visit their favorite winery just before lunch to taste their new Cabernet Sauvignon. The owner recognizes them as they walk in the door and immediately seats them on the patio overlooking the vineyard. Two glasses appear, and as the owner tells them about the new Cabernet, Brutus prepares for an onslaught of blackberry... Continue Reading
It’s common to think that process improvement initiatives are meant to cater only to manufacturing processes, simply because manufacturing is where Lean and Six Sigma began. However, many other industries, in particular financial services and banking, also rely on data analysis and Lean Six Sigma tools to improve processes. Rod Toro is a business process improvement manager at Edward Jones, and I... Continue Reading
The 2014 ASQ World Conference on Quality and Improvement is coming up in early May in Dallas, and this year’s International Team Excellence Award Process (ITEA) will also come to a close at the conference, as winners from the finalist teams will be chosen for ASQ gold, silver, or bronze-level statuses. What’s ITEA? The annual ASQ ITEA process celebrates the accomplishments of quality improvement... Continue Reading
By now, you probably know that Minitab 17 includes Design of Experiments (DOE) in the Assistant. We already spent some time looking at 5 highlights when you create a screening experiment with the Assistant in Minitab 17. But the Assistant can also help you make sense of the data you collect for your experiment. After you create a design with the Assistant, choose Assistant > DOE > Analyze... Continue Reading
If you’ve been looking at Minitab 17, you’ve noticed a lot of new enhancements. For me, the biggest of these is the addition of Design of Experiments (DOE) to the Assistant. DOE in the Assistant has so many exciting aspects it’s hard to take it all in at once, but here are 5 highlights for when you plan and create a screening experiment: 1. Just-in-time guidance If you’re lucky, you’ve had the... Continue Reading
What factors significantly affect how quickly my couch-potato pooch obeys the “Lay Down” command? The cushiness of the floor surface? The tone of voice used? The type of reward she gets? How hungry she is? I created a 1/8 fraction Resolution IV design for 7 factors and collected response data for 16 runs. Now it’s time to analyze the data in Minitab, using  Stat > DOE > Factorial > Analyze Factorial... Continue Reading
Nala, our 6-year-old golden retriever, loves her dogma. That's her sitting in front of church on Sunday morning. But she's not crazy about her catechism. For example, she doesn't always dutifully follow the "Lay Down" commandment.   What factors may be influencing her response? We're performing a DOE screening experiment to find out. In this post, we'll use Minitab Statistical Software to Create the... Continue Reading
Design of experiments (DOE) is an extremely practical and cost-effective way to study the effects of different factors and their interactions on a response. But finding your way through DOE-land can be daunting when you're just getting started. So I've enlisted the support of a friendly golden retriever as a guide dog to walk us through a simple DOE screening experiment. Nala, the golden retriever,... Continue Reading
Recently, a customer called our Technical Support team about a Design of Experiment he was performing in Minitab Statistical Software. After they helped to answer his question, the researcher pointed our team to an interesting DOE he and his colleagues conducted that involved using nasal casts to predict the drug delivery of nasal spray. The study has already been published, and you can read... Continue Reading
All processes are affected by various sources of variations over time. Products which are designed based on optimal settings, will, in reality, tend to drift away from their ideal settings during the manufacturing process. Environmental fluctuations and process variability often cause major quality problems. Focusing only on costs and performances is not enough. Sensitivity to deterioration and... Continue Reading
The 2013 ASQ World Conference is taking place this week in Indianapolis, Indiana, and it's been a treat to see how our software was used in the projects highlighted in many of the presentations. As a supporter of the conference, a key event for quality practitioners around the world, Minitab was proud to sponsor one of the presentations that seemed to get a lot of attendees talking. Scott... Continue Reading
You know the drill…you’re in Six Sigma training and you’re learning how to conduct a design of experiment (DOE). Everything is making sense, and you’ve started thinking about how you’ll apply what you are learning to find the optimal settings of a machine on the factory floor. You’ve even got the DOE setup chosen and you know the factors you want to test … Then … BAM! … You’re on your own and you... Continue Reading
When I talk to quality professionals about how they use statistics, one tool they mention again and again is design of experiments, or DOE. I'd never even heard the term before I started getting involved in quality improvement efforts, but now that I've learned how it works, I wonder why I didn't learn about it sooner. If you need to find out how several factors are affecting a process outcome,... Continue Reading
Lean Six Sigma and process excellence leaders are often asked to “remove defects” from products and processes. This can be quite a challenge! Lou Johnson, senior Minitab technical trainer and mentor, has some tips that might help if you’re faced with this situation. I had the chance to talk with Lou, and here’s what he shared with me about how to first approach a DOE. How to Approach a DOE Before... Continue Reading
It’s the most wonderful time of the year – the time for holiday bakers and cookie monsters to unite! So what’s a quality improvement professional to do when his favorite sugar cookie recipe produced cookies that failed to hold their festive holiday shapes after being baked? Run a Design of Experiment (DOE), of course! A Fractional Factorial Experiment Bill Howell, an avid baker and... Continue Reading
Design of experiments, experimental design, or just "gathering some data." Whatever you want to call it, your approach to doing it will affect the results you get. Have you ever wondered about all those contradictory studies in the news, especially regarding what's good and bad for you? Coffee is good for you, one headline says. It's bad for you, says the next. And if you read beyond the headlines,... Continue Reading
We’ve used design of experiments to look at the data. We’ve seen that the center points are statistically insignificant. We’ve seen that blocks help account for the unstable conditions during the collection of the data. Now for the exciting part: let’s choose a model to use to predict where the gummi bears will land when we launch them. Various criteria exist for how to choose a model, so we’re... Continue Reading