Tips and Techniques for Statistics and Quality Improvement

Blog posts and articles about using Minitab software in quality improvement projects, research, and more.

Minitab 17.2 is available. You can check out all of the new stuff on the What’s New Page, but I would say that a little demonstration is in order. Here are some new shortcuts that make arranging your data easier in Minitab 17.2. Sorting Let’s suppose that you had copied some Human Development Index data into Minitab and wanted to sort countries in the order of their rank. In the past, you would have... Continue Reading
To choose the right statistical analysis, you need to know the distribution of your data. Suppose you want to assess the capability of your process. If you conduct an analysis that assumes the data follow a normal distribution when, in fact, the data are nonnormal, your results will be inaccurate. To avoid this costly error, you must determine the distribution of your data. So, how do you determine... Continue Reading
Imagine that you are watching a race and that you are located close to the finish line. When the first and fastest runners complete the race, the differences in times between them will probably be quite small. Now wait until the last runners arrive and consider their finishing times. For these slowest runners, the differences in completion times will be extremely large. This is due to the fact that... Continue Reading
by Lion "Ari" Ondiappan Arivazhagan, guest blogger.   Predicting project completion times is one of the major challenges project managers face. Project schedule overruns are quite common due to the high uncertainty in estimating the amount of time activities require, a lack of historical data about project completion, organizational culture, inadequate skills, the complex and elaborative nature of... Continue Reading
This is a companion post for a series of blog posts about understanding hypothesis tests. In this series, I create a graphical equivalent to a 1-sample t-test and confidence interval to help you understand how it works more intuitively. This post focuses entirely on the steps required to create the graphs. It’s a fairly technical and task-oriented post designed for those who need to create the... Continue Reading
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
Monte Carlo simulation has all kinds of useful manufacturing applications. And - in celebration of Pi Day - I thought it would be apropos to show how you can even use Monte Carlo simulation to estimate pi, which of course is the mathematical constant that represents the ratio of a circle’s circumference to its diameter. For our example, let’s start with a circle of radius 1 inscribed within a... 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
We’ve been pretty excited about March Madness here at Minitab. Kevin Rudy’s been busy creating his regression model and predicting the winners for the 2015 NCAA Men’s Basketball Tournament. But we’re not the only ones. Lots of folks are doing their best analysis to help you plan out your bracket now that the tip-offs for the round of 64 are just a day away. As you ponder your last-minute changes,... 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
Are you ready for some madness? Me too! So let’s break down the brackets. I’ll be using the Sagarin Predictor ratings to determine the probability each team has of advancing using a binary logistic model created with Minitab Statistical Software. You can find the details of how the probabilities are being calculated here. Before we start, I’d also like to mention one other set of basketball... Continue Reading
The NCAA Tournament is right around the corner, and you know what that means: It’s time to start thinking about how you’re going to fill out your bracket! For the last two years I’ve used the Sagarin Predictor Ratings to predict the tournament. However, there is a problem with that strategy this year. The old method uses a regression model that calculates the probability one team has of beating... Continue Reading
Welcome to the Hypothesis Test Casino! The featured game of the house is roulette. But this is no ordinary game of roulette. This is p-value roulette! Here’s how it works: We have two roulette wheels, the Null wheel and the Alternative wheel. Each wheel has 20 slots (instead of the usual 37 or 38). You get to bet on one slot. What happens if the ball lands in the slot you bet on? Well, that depends... Continue Reading
Suppose that you have designed a brand new product with many improved features that well help create a much better customer experience. Now you must ensure that it is manufactured according to the best quality and reliability standards, so that it gets the excellent long-term reputation it deserves from potential customers. You need to move quickly and seamlessly from Research and Development into... Continue Reading
In England, with only a few months left, the Barclay’s Premier League is about to enter the final run in to finish up the season. While the top two spots seem pretty locked up with Chelsea and Manchester City showing their class, the fight for the other two spots in the coveted top 4 promises to entertain to the very last weekend. This is key, because only the top 4 finishers qualify for next... 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
I am M. G - L - M. That G - L - M! That G - L - M! I do not like That G - L - M. Do you like Means and histograms? I do not like them, G - L - M. I do not like Means and histograms. Would you like them Halved or squared? Would you like them As a pair? I would not like them Halved or squared. I would not like them As a pair. I do not like Means and histograms. I do not like them, G - L - M. Would you like... 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
Forbes ranked the world’s billionaires for 2015 this week, which gives us a good opportunity to have fun with some data. After all, when you’re talking about billions, the most fun you can have is to see how big the number can get. If you copy and paste Forbes’ data directly, you’ll find it a bit messy for analysis. For example, the sources of wealth for the billionaires include Telcom, Telecom,... 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