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Regression with Meat Ants: Analyzing a Count Response (Part II)
My previous post showed an example of using ordinary linear regression to model a count response. For that particular count data, shown by the blue circles on the dot plot below, the model assumptions...
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Regression with Meat Ants: Analyzing a Count Response (Part III)
If you use ordinary linear regression with a response of count data, if may work out fine (Part 1), or you may run into some problems (Part 2).Given that a count response could be problematic, why not...
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College Football and the High-Variance Strategy
Variance is a measure of how much the data are scattered about their mean. Usually we want to minimize it as much as possible. A manufacturer of screws wants to minimize the variation in the length of...
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Reducing the Size of Your Response Surface Design
It sometimes may be prohibitively expensive or time-consuming to gather data for all runs for a designed experiment (DOE).For example, a 6 factor, 2-level factorial design can entail 64 experimental...
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Which Supplier Should You Choose? Check the Data.
Whatever industry you're in, you're going to need to buy supplies. If you're a printer, you'll need to purchase inks, various types of printing equipment, and paper. If you're in manufacturing, you'll...
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An Easy Data Set to Summarize with Minitab's Assistant
When I started out on the blog, I spent some time showing some data sets that would be easy to illustrate statistical concepts. It’s easier to show someone how something works with something familiar...
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Repeated Measures Designs: Benefits, Challenges, and an ANOVA Example
Repeated measures designs don’t fit our impression of a typical experiment in several key ways. When we think of an experiment, we often think of a design that has a clear distinction between the...
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Big Ten 4th Down Calculator: Week 1
This summer, I created a model to determine the correct 4th down decision. But whether it’s for business or some personal interest, creating a model is just the starting point. The real benefits come...
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The Longest Drive: Golf and Design of Experiments, Part 1
As we broke for lunch, two participants in the training class began to discuss, debate, and finally fight over a fundamental task in golf—how to drive the ball the farthest off the tee. Both were avid...
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Regression in the Real World
I recently guest lectured for an applied regression analysis course at Penn State. Now, before you begin making certain assumptions—because as any statistician will tell you, assumptions are important...
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Everyone's Talking "Big Data"...But Size Isn't What Matters
You know what the big thing is in the data analysis world—"Big Data." Big, big, big, very big data. Massive data. ENORMOUS data. Data that is just brain-bendingly big. Data so big that we need globally...
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How to Improve Cpk
You run a capability analysis and your Cpk is bad. Now what? First, let’s first start by defining what “bad” is. In simple terms, the smaller the Cpk, the more defects you have. So the larger your Cpk...
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How Many Samples Do You Need to Be Confident Your Product Is Good?
How many samples do you need to be “95% confident that at least 95%—or even 99%—of your product is good?The answer depends on the type of response variable you are using, categorical or continuous. The...
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The Longest Drive: Golf and Design of Experiments, Part 2
Step 1 in our DOE problem-solving methodology is to use process experts, literature, or past experiments to characterize the process and define the problem. Since I had little experience with golf...
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Make Similar Graphs to Unclutter Data from the American Consumer Survey
September 17 marked the release of new information from the American Community Survey (ACS) from the U.S. Census Bureau. Here’s a bar chart of what the press releases looked like for that day:Clearly...
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P Values and the Replication of Experiments
An exciting new study sheds light on the relationship between P values and the replication of experimental results. This study highlights issues that I've emphasized repeatedly—it is crucial to...
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Specification Limits and Stability Studies
I was recently asked a couple of questions about stability studies in Minitab.Question 1: If you enter in a lower and upper spec in the Stability Study dialog window, why do I see only one confidence...
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The Longest Drive: Golf and Design of Experiments, Part 3
Step 2 in our DOE problem-solving methodology is to design the data collection plan you will use to study the factors in your experiment. Of course, you will have to incorporate blocking and covariates...
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Big Ten 4th Down Calculator: Week 2
It was a wild weekend in the Big Ten. Four of the six conference games were decided by a touchdown or less, and all of those close games means we have plenty of 4th down decisions to analyze.If you're...
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Does Every Good Analytical Chemist Need to Be a Statistician?
I read trade publications that cover everything from banking to biotech, looking for interesting perspectives on data analysis and statistics, especially where it pertains to quality...
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