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Eston Martz

I’m not a “math” person, but I've overcome fear of statistics and acquired a real passion for it. And if I can learn to understand and apply statistics, so can you. Continue Reading »

A reader asked a great question in response to a post I wrote about Pareto charts. Our readers typically do ask great questions, but this one turned out to be more difficult to answer than it first seemed. My correspondent wrote:  My understanding is that when you have count data, a bar chart is the way to go. The gaps between the bars emphasize that the data are not measured on a continuous scale.... Continue Reading
We hosted our first-ever Minitab Insights conference in September, and if you were among the attendees, you already know the caliber of the speakers and the value of the information they shared. Experts from a wide range of industries offered a lot of great lessons about how they use data analysis to improve business practices and solve a variety of problems. I blogged earlier about five key... Continue Reading
I watched an old motorcycle flick from the 1960s the other night, and I was struck by the bikers' slang. They had a language all their own. Just like statisticians, whose manner of speaking often confounds those who aren't hep to the lingo of data analysis. It got me thinking...what if there were an all-statistician biker gang? Call them the Nulls Angels. Imagine them in their colors, tearing... Continue Reading
If you were among the 300 people who attended the first-ever Minitab Insights conference in September, you already know how powerful it was. Attendees learned how practitioners from a wide range of industries use data analysis to address a variety of problems, find solutions, and improve business practices. In the coming weeks and months, we will share more of the great insights and guidance shared... Continue Reading
I confess: I'm not a natural-born decision-maker. Some people—my wife, for example—can assess even very complex situations, consider the options, and confidently choose a way forward. Me? I get anxious about deciding what to eat for lunch. So you can imagine what it used to be like when I needed to confront a really big decision or problem. My approach, to paraphrase the Byrds, was "Re:... Continue Reading
The other day I was talking with a friend about control charts, and I wanted to share an example one of my colleagues wrote on the Minitab Blog.  Looking back through the index for "control charts" reminded me just how much material we've published on this topic. Whether you're just getting started with control charts, or you're an old hand at statistical process control, you'll find some valuable... Continue Reading
So the data you nurtured, that you worked so hard to format and make useful, failed the normality test. Time to face the truth: despite your best efforts, that data set is never going to measure up to the assumption you may have been trained to fervently look for. Your data's lack of normality seems to make it poorly suited for analysis. Now what? Take it easy. Don't get uptight. Just let your data... Continue Reading
Figures lie, so they say, and liars figure. A recent post at Ben Orlin's always-amusing mathwithbaddrawings.com blog nicely encapsulates why so many people feel wary about anything related to statistics and data analysis. Do take a moment to check it out, it's a fast read. In all of the scenarios Orlin offers in his post, the statistical statements are completely accurate, but the person offering... Continue Reading
You need to consider many factors when you’re buying a used car. Once you narrow your choice down to a particular car model, you can get a wealth of information about individual cars on the market through the Internet. How do you navigate through it all to find the best deal?  By analyzing the data you have available.   Let's look at how this works using the Assistant in Minitab Statistical... Continue Reading
Design of Experiments is an extremely powerful statistical method, and we added a DOE tool to the Assistant in Minitab to make it more accessible to more people. Since it's summer grilling season, I'm applying the Assistant's DOE tool to outdoor cooking. Earlier, I showed you how to set up a designed experiment that will let you optimize how you grill steaks.  If you're not already using it and you... Continue Reading
Design of Experiments (DOE) has a reputation for difficulty, and to an extent, this statistical method deserves that reputation. While it's easy to grasp the basic idea—acquire the maximum amount of information from the fewest number of experimental runs—practical application of this tool can quickly become very confusing.  Even if you're a long-time user of designed experiments, it's still easy to... Continue Reading
Earlier this month, PLOS.org published an article titled "Ten Simple Rules for Effective Statistical Practice." The 10 rules are good reading for anyone who draws conclusions and makes decisions based on data, whether you're trying to extend the boundaries of scientific knowledge or make good decisions for your business.  Carnegie Mellon University's Robert E. Kass and several co-authors devised... Continue Reading
By looking at the data we have about 500 cardiac patients, we've learned that easy access to the hospital and good transportation are key factors influencing participation in a rehabilitation program. Past data shows that each month, about 15 of the patients discharged after cardiac surgery do not have a car. Providing transportation to the hospital might make these patients more likely to join... Continue Reading
In part 2 of this series, we used graphs and tables to see how individual factors affected rates of patient participation in a cardiac rehabilitation program. This initial look at the data indicated that ease of access to the hospital was a very important contributor to patient participation. Given this revelation, a bus or shuttle service for people who do not have cars might be a good way to... Continue Reading
My previous post covered the initial phases of a project to attract and retain more patients in a cardiac rehabilitation program, as described in a 2011 Quality Engineering article. A Pareto chart of the reasons enrolled patients left the program indicated that the hospital could do little to encourage participants to attend a greater number of sessions, so the team focused on increasing initial... Continue Reading
Over the past year I've been able to work with and learn from practitioners and experts who are using data analysis and Six Sigma to improve the quality of healthcare, both in terms of operational efficiency and better patient outcomes. I've been struck by how frequently a very basic analysis can lead to remarkable improvements, but some insights cannot be attained without conducting more... Continue Reading
There has been plenty of noisy disagreement about the state of health care in the past several years, but when you get beyond the controversies surrounding various programs and changes, a great deal of common ground exists. Everyone agrees that there's a lot of waste and inefficiency in the way we've been doing things, and that health care should be delivered as efficiently and effectively as... Continue Reading
If you want to convince someone that at least a basic understanding of statistics is an essential life skill, bring up the case of Lucia de Berk. Hers is a story that's too awful to be true—except that it is completely true. A flawed analysis irrevocably altered de Berk's life and kept her behind bars for five years, and the fact that this analysis targeted and harmed just one person makes it more... Continue Reading
In an earlier post, I shared an overview of acceptance sampling, a method that lets you evaluate a sample of items from a larger batch of products (for instance, electronics components you've sourced from a new supplier) and use that sample to decide whether or not you should accept or reject the entire shipment.  There are two approaches to acceptance sampling. If you do it by attributes, you... Continue Reading
Now that we've seen how easy it is to create plans for acceptance sampling by variables, and to compare different sampling plans, it's time to see how to actually analyze the data you collect when you follow the sampling plan.  If you'd like to follow along and you're not already using Minitab, please download the free 30-day trial.  Collecting the Data for Acceptance Sampling by Variable If you'll... Continue Reading