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Data Analysis

Blog posts and articles with tips for analyzing data for quality improvement methodologies, including Six Sigma and Lean.

I always knew I was different. Even as a kid. “Is that me? Way out there in left field?” I asked the doc. “Yes,” he nodded, as he looked at my chart. “I used brushing to identify you on the graph.” I wasn’t sure I liked getting brushed. It felt like my true identify was being detected and displayed in a window for all to see. The doctor must have sensed my discomfort. “It’s not uncommon—even for those... Continue Reading
What do significance levels and P values mean in hypothesis tests? What is statistical significance anyway? In this post, I’ll continue to focus on concepts and graphs to help you gain a more intuitive understanding of how hypothesis tests work in statistics. To bring it to life, I’ll add the significance level and P value to the graph in my previous post in order to perform a graphical version of... Continue Reading
Our vacation planning has begun. My daughter has requested a trip to Disney World as her high school graduation present. For most people, trip planning might mean a simple phone call to the local travel agent or an even simpler do-it-yourself online booking. Not for me. As a statistician, a request like this means I’ve got a lot of data analysis ahead. So many travel questions require (in my... Continue Reading
There are times when we are deep in a particular analysis and simply cannot seem to get past this dialog window, or that error message. Fortunately, the support team at Minitab is here to help. Here is a list of situations people have called us about when using Minitab, and how to solve them. If your situation isn't listed, please call Minitab Technical Support, and we will be happy to assist.... Continue Reading
Hypothesis testing is an essential procedure in statistics. A hypothesis test evaluates two mutually exclusive statements about a population to determine which statement is best supported by the sample data. When we say that a finding is statistically significant, it’s thanks to a hypothesis test. How do these tests really work and what does statistical significance actually mean? In this series of... Continue Reading
Many things have shocked me since having my first baby back in August. I didn’t think it was possible to be so tired that it actually hurt, and I also didn’t think that changing 10+ diapers a day would actually be the norm (or that needing to perform 10+ outfit changes was even possible, let alone necessary). I also didn’t think that we’d fall in love so hard with the little guy. What a wonderful,... Continue Reading
As I’m sure you’ve heard by now, Kentucky is really good at basketball. They're the only team in the country without a loss, and they have a realistic shot at becoming to first team to win the championship with an undefeated record since the 1976 Indiana Hoosiers. Under any ranking system you want to use, Kentucky is clearly the #1 team in college basketball. Well, almost any ranking system. All... Continue Reading
In my previous post, I showed you how to set up data collection for a gage R&R analysis using the Assistant in Minitab 17. In this case, the goal of the gage R&R study is to test whether a new tool provides an effective metric for assessing resident supervision in a medical facility.   As noted in that post, I'm drawing on one of my favorite bloggers about health care quality, David Kashmer of the... Continue Reading
I left off last with a post outlining how the Six Sigma students at Rose-Hulman were working on a project to reduce the amount of recycling thrown in the normal trash cans in all of the academic buildings at the institution. Using the DMAIC methodology for completing improvement projects, they had already defined the problem at hand: how could the amount of recycling that’s thrown in the normal trash... Continue Reading
The Minitab Fan section of the Minitab blog is your chance to share with our readers! We always love to hear how you are using Minitab products for quality improvement projects, Lean Six Sigma initiatives, research and data analysis, and more. If our software has helped you, please share your Minitab story, too! My LSS coach suggested that I regularly conduct data analysis to refresh my Minitab... Continue Reading
  In my experience, one of the hardest concepts for users to wrap their head around revolves around the Power and Sample Size menu in Minitab's statistical software, and more specifically, the field that asks for the "difference" or "difference to detect."  Let’s start with power. In statistics, the definition of power is the probability that you will correctly reject the null hypothesis when it is... Continue Reading
by Matthew Barsalou, guest blogger.  E. E. Doc Smith, one of the greatest authors ever, wrote many classic books such as The Skylark of Space and his Lensman series. Doc Smith’s imagination knew no limits; his Galactic Patrol had millions of combat fleets under its command and possessed planets turned into movable, armored weapons platforms. Some of the Galactic Patrol’s weapons may be well... Continue Reading
In my recent meetings with people from various companies in the service industries, I realized that one of the problems they face is that they were collecting large amounts of "qualitative" data: types of product, customer profiles, different subsidiaries, several customer requirements, etc. As I discussed in my previous post, one way to look at qualitative data is to use different types of... Continue Reading
In several previous blogs, I have discussed the use of statistics for quality improvement in the service sector. Understandably, services account for a very large part of the economy. Lately, when meeting with several people from financial companies, I realized that one of the problems they faced was that they were collecting large amounts of "qualitative" data: types of product, customer... Continue Reading
I really can’t make this stuff up. I wrote a post a couple of years ago entitled: “How to Talk to Your Kids about Six Sigma and Quality Improvement,” in which I lamented about “Community Hero” day in my daughter’s 1st grade class and the need to explain to her why I wasn’t at the "community-hero-level" of Maggie’s Mommy, the pediatrician. Well, now it's two years later and my son, Thomas, is in... Continue Reading
by Matthew Barsalou, guest blogger Recently Minitab’s Joel Smith posted a blog about an incident in which he was pooped on by a bird. Twice. I suspect many people would assume the odds of it happening twice are very low, so they would incorrectly assume they are safer after such a rare event happens. I don’t have data on how often birds poop on one person, and I assume Joel is unwilling to stand... Continue Reading
Minitab's capability analysis output gives you estimates of the capability indices Ppk and Cpk, and we receive many questions about the difference between them. Some of my colleagues have taken other approaches to explain the difference between Ppk and Cpk, so I wanted to show you how they differ by detailing precisely how each one is calculated.  When you're using statistical softwarelike Minitab,... Continue Reading
In technical support, we frequently receive calls from Minitab users who have questions about the differences between Cpk and Ppk.  Michelle Paret already wrote a great post about the differences between Cpk and Ppk, but it also helps to have a better understanding of the math behind these numbers. So in this post I will show you how to calculate Ppk using Minitab’s default settings when the... Continue Reading
Have you ever had a probability plot that looks like this? The probability plot above is based on patient weight (in pounds) after surgery minus patient weight (again, in pounds) before surgery. The red line appears to go through the data, indicating a good fit to the Normal, but there are clusters of plotting points at the same measured value. This occurs on a probability plot when there are many... Continue Reading
Greetings fair reader. In the past, I've written several posts with practical tips related to Minitab graphs, such as: How to discuss the sensitive issue of P charts and Laney P' charts with your doctor How to use a G chart to monitor parenting success How to use a scatterplot to start your own doomsday cult In this post, I thought I'd take a step back and explore the historical side of Minitab's... Continue Reading