Blog posts and articles about statistical principles in quality improvement methods like Lean and Six Sigma.

People who are ill frequently need medication. But if they miss a dose, or receive the wrong medication—or even get the wrong dose of the right medication—the results can be disastrous.  So medical professionals have a lot at stake in making sure patients get the right medicine, in the right amount, at the right time. But hospitals and other medical facilities are complex systems, and mistakes do... Continue Reading
This week is National Healthcare Quality Week, started by the National Association for Healthcare Quality to increase awareness of healthcare quality programs and to highlight the work of healthcare quality professionals and their influence on improved patient care outcomes. In honor of the celebration, I wanted to point you to a few case studies featuring Minitab customers in the healthcare field... Continue Reading
Week 4 in the Big Ten featured a couple blowouts, an insane comeback, and the worst punt in the history of recorded time. But before we get to all that, here's my weekly blurb on what exactly the 4th down calculator is.  I've used Minitab Statistical Software to create a model to determine the correct 4th down decision. And for the rest of the college football season, I'll use that model to track... Continue Reading
Part of the fun of sports statistics is that many of the questions are unanswerable in an absolute sense. After a project to improve patient satisfaction scores at a hospital, you can and should measure patient satisfaction scores to determine that the increase met your goals. In sports, we don’t have exact comparisons from player to player, especially when their careers don’t even overlap. Thus,... Continue Reading
With Speaker John Boehner resigning, Kevin McCarthy quitting before the vote for him to be Speaker, and a possible government shutdown in the works, the Freedom Caucus has certainly been in the news frequently! Depending on your political bent, the Freedom Caucus has caused quite a disruption for either good or bad.  Who are these politicians? The Freedom Caucus is a group of approximately 40... Continue Reading
Every single Big Ten team played a conference game this week, giving us the most 4th downs to analyze yet. Last week, 4 of the 6 games were decided by one possession. This week only 2 of the 7 games were decided by one possession, so let's see if the losing teams missed opportunities to keep the game close! But first, a quick refresher on what this is.  I've used Minitab Statistical Software to... Continue Reading
Step 3 in our DOE problem solving methodology is to determine how many times to replicate the base experiment plan. The discussion in Part 3 ended with the conclusion that our 4 factors could best be studied using all 16 combinations of the high and low settings for each factor, a full factorial. Each golfer will perform half of the sixteen possible combinations and each golfer’s data could stand as... Continue Reading
You've collected a bunch of data. It wasn't easy, but you did it. Yep, there it is, right there...just look at all those numbers, right there in neat columns and rows. Congratulations. I hate to ask...but what are you going to do with your data? If you're not sure precisely what to do with the data you've got, graphing it is a great way to get some valuable insight and direction. And a good graph to... Continue Reading
While most of us work in Minitab Statistical Software using our preferred language, some need to share Minitab project files or present the results in a different language. Others among us just want to play around with the languages because playing around with Minitab is fun! Thankfully, Minitab offers our statistical softwarein eight languages, including English, French, German, Japanese, Korean,... Continue Reading
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 improvement. Recently I read a great blog post from Tony Taylor, an analytical chemist with a background in pharmaceuticals. In it, he discusses the implications of the FDA's updated guidance for industry analytical... Continue Reading
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 new to the Big Ten 4th Down Calculator, I've used Minitab Statistical Software to create a model to determine the correct 4th down decision. And for the rest of the college football season, I'll use... Continue Reading
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 bound per fitted line on the resulting graph? Shouldn’t there be two? You use a stability study to analyze the stability of a product over time and to determine the product's shelf life. In order to... Continue Reading
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 interpret P values correctly, and significant results must be replicated to be trustworthy. The study also supports my disagreement with the decision by the Journal of Basic and Applied Social Psychology to b... Continue Reading
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 there was a theme in play, one that was great news for major metropolitan areas. The Census Bureau even released a graph showing that the percentage of people within the 25 most populous metropolitan... Continue Reading
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 myself, this was an important step for me. This is not an uncommon situation. Experiment designers often find themselves working on processes that they have little or no experience with. For example, a... Continue Reading
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 type of response will dictate whether you 'll use: Attribute Sampling: Determine the sample size for a categorical response that classifies each unit as Good or Bad (or, perhaps, In-spec or... Continue Reading
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 is, the better. Many practitioners use a Cpk of 1.33 as the gold standard, so we’ll treat that as the gold standard here, too. Suppose we collect some data and run a capability analysis using Minitab St... Continue Reading
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 interconnected supercomputers that haven't even been built yet just to contain one one-billionth of it. That's the kind of big data everybody's so excited about.  Whatever. There's no denying that... Continue Reading
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 in regression—you should know that I have no teaching experience whatsoever, and I’m not much older than the students I addressed. I’m just 5 years removed from my undergraduate days at Virginia Tech,... Continue Reading
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 from applying your model. And for the Big Ten 4th down calculator, the time to apply the model is now! On Saturday night, Penn State and Rutgers officially kicked off conference play for the 2015 Big... Continue Reading