Patrick Runkel

Communicating statistical concepts quickly and clearly is just as critical as being able to calculate them, so I focus on quick, practical insights about statistics to help you make data-driven decisions. Continue Reading »

If you regularly perform regression analysis, you know that R2 is a statistic used to evaluate the fit of your model. You may even know the standard definition of R2: the percentage of variation in the response that is explained by the model. Fair enough. With Minitab Statistical Software doing all the heavy lifting to calculate your R2 values, that may be all you ever need to know. But if you’re... Continue Reading
This close to the holidays, it’s hard to stay focused on work. I should be writing a post about useful estimation tools for quality statistics. But all those yuletide carols about hosts of angels singing from on high have distracted me. Alas, I’ve fallen into the clutches of one of the world’s oldest estimation problems, posed centuries ago by medieval scholars: Just how many heavenly angels can... 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
What do you see when you look at the image at right? Do you see a bulging sphere that stretches the checkerboard pattern in the center, causing its lines to curve? Are you sure? Look again. This time, test any “curved” line by holding a straightedge next to it. The image is actually composed of small squares and straight lines. Yet, when perceived as a composite whole, it creates a completely... Continue Reading
Does the prospect of a looming U.S. government shutdown depress you? Are you tired of the ongoing game of Chicken played over our federal budget? The dissonant hysterics of deficit drama queens? The glib arrogance of deficit deniers? Then it might be a good time to take a break and focus on something more pleasant. Something you can control. Something you can improve and make more beautiful. Like... Continue Reading
Defects can cause a lot of pain to your customer. They can also cause a lot of pain inside your body. The picture at right shows my broken right clavicle. Ouch! You might think of it as the defective output from my bicycling process, which needs improvement. Sitting around all summer cinched up in a foam orthopedic brace hasn’t exactly been wild and wacky 50s-style fun at the beach. But the injury has... Continue Reading
It’s wildfire season out West. Time to be in awe of the destructive power of Nature. According to active fire maps by the USDA Forest Service, over 300 fires are now burning across a total of 1.5 million acres—including 35 large, uncontained blazes. Shifting winds, humidity, and terrain can quickly alter a fire's intensity. In extreme conditions, flames can reach over 150 feet, with temperatures... Continue Reading
True confession: Nothing fires quickly from the top of my head. At least nothing very lucid or useful. To come up with a good idea, I have to dredge thoughts slowly from the thick sludge and sediment in my brain.  It's not always easy—there are deeply encrusted layers in my cerebral cortex that go all the way back to the Paleozoic era. So coming up with a useful data display—one that uncovers hidden... Continue Reading
My Uncle Joe is always fantasizing about ways to outsmart Father Time. “Suppose you could reverse your aging process at some fixed point in your life,” he says to me, a crazed gleam in his eye. “So you could pick any age to turn the clock backwards and start aging in reverse. What age would you pick to try to maximize your life span?”   In other words, suppose you pick age 75. That means you’d... Continue Reading
Boxers or briefs. Republican or Democrat. Yin or yang. Why is it that life often seems to boil down to two choices? Heck, it even happens when you open the Basic Stats menu in Minitab. You’ll see a choice between a 2-sample t-test and a paired t-test: Which test should you choose? And what’s at stake? Ask a statistician, and you might get this response: "Elementary, my dear Watson. Choose the 2-sample... Continue Reading
A t-test is one of the most frequently used procedures in statistics. But even people who frequently use t-tests often don’t know exactly what happens when their data are wheeled away and operated upon behind the curtain using statistical software like Minitab. It’s worth taking a quick peek behind that curtain. Because if you know how a t-test works, you can understand what your results really mean.... Continue Reading
Unless you’re 3 years old, you probably can’t have things just the way you want them all the time.   You can’t always have peanut butter and ranch dressing on your toast. Or ketchup on your pineapple. Or sugar sprinkles on your peas. But there is one small arena in life over which you can still exert your control.  Tools > Options in Minitab's statistical softwareallows you to change selected default... Continue Reading
  “Shall I compare thee to a standard normal distribution?   Thou art more symmetric and more bell-shaped…”  — Melvin Shakespeare (William’s lesser-known statistician brother) The Greek philosopher Aristotle believed that symmetry was one of the primary elements of the universal ideal of beauty. Over 2000 years later, emerging research seems to bear him out.  Studies suggest we tend to be more... Continue Reading
Using a Survey of Aquatic Bugs to Estimate Stream Quality As we click, flip, and scroll through hundreds of sites and channels, cruising for our daily dose of e-thrills, it’s easy to forget there’s a beautiful, wild, creative universe right in our backyards. I had the chance to experience a tiny part of that universe on a recent Saturday afternoon, when a couple of friends, Yolanda and Monika, asked... Continue Reading
by Patrique Roonquel, guest blogger Institut Sacre Bleu I enjoy using Minitab Statistical Software to uncover the vast causal relationships unfolding in the universe all around me.  What kind of novel things have I proven with Minitab? Almost anything you can imagine, mon petite shoe. For example, the fitted line plot below clearly shows one thing:  it’s time for our political parties to stop all the... Continue Reading
Has it happened to you?   You organize a brainstorming session to begin analyzing your process. At the kick-off meeting, several people sit with arms crossed, lips pursed, eyes cast downward. Frequently, they’re the ones who’ve worked at the process for most of their professional lives. “Here we go again. Wasting time to prove the obvious,” their faces say. “I’ve done my job for years. You’re not... Continue Reading
If the title of this post made you think you’d be reading about Abraham Lincoln and Tyra Banks, you’re only half right.  A few weeks ago, statistician and journalist Nate Silver published an interesting post  on how U.S. presidents are ranked by historians. Silver showed that the percentage of electoral votes that a U.S. president receives in his 2nd term election serves as a rough predictor of... Continue Reading
  Lionel Loosefit has been hauled to court for violating the assumptions of regression analysis. On the last day of the trial, the prosecution and defense present their closing arguments. And the fate of Mr. Loosefit is decided by judge and jury... The Prosecution's Summary Prosecutor: Ladies and gentlemen, we’ve presented a slew of evidence in this trial. You’ve seen, with your own eyes, every... Continue Reading