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Data Analysis Software

Blog posts and articles with tips for using statistical software to analyze data for quality improvement.

In my previous post, I showed you that the coefficients are different when choosing (-1,0,1) vs (1,0) coding schemes for General Linear Model (or Regression).  We used the two different equations to calculate the same fitted values. Here I will focus on showing what the different coefficients represent.  Let's use the data and models from the last blog post: We can display the means for each level... Continue Reading
Since Minitab 17 Statistical Software launched in February 2014, we've gotten great feedback from many people have been using the General Linear Model and Regression tools. But in speaking with people as part of Minitab's Technical Support team, I've found many are noticing that there are two coding schemes available with each. We frequently get calls from people asking how the coding scheme you... Continue Reading
Earlier, I wrote about the different types of data statisticians typically encounter. In this post, we're going to look at why, when given a choice in the matter, we prefer to analyze continuous data rather than categorical/attribute or discrete data.  As a reminder, when we assign something to a group or give it a name, we have created attribute or categorical data.  If we count something, like... Continue Reading
The first summer blockbuster of 2015 was released two weeks ago—The Avengers: Age of Ultron. The first Avengers film featured a pretty well known cast of superheroes (if, of course, you’re a superhero fan). However, in the 40-year run of the Avengers comic book, that team has evolved to keep the material fresh and to allow some characters to go their solo ways. I want to use Minitab's statistical... Continue Reading
In previous posts, I discussed the results of a recycling project done by Six Sigma students at Rose-Hulman Institute of Technology last spring. (If you’re playing catch up, you can read Part I and Part II.) The students did an awesome job reducing the amount of recycling that was thrown into the normal trash cans across all of the institution’s academic buildings. At the end of the spring... Continue Reading
by Matthew Barsalou, guest blogger.  The old saying “if it walks like a duck, quacks like a duck and looks like a duck, then it must be a duck” may be appropriate in bird watching; however, the same idea can’t be applied when observing a statistical distribution. The dedicated ornithologist is often armed with binoculars and a field guide to the local birds and this should be sufficient. A... Continue Reading
This week I'm at the American Society for Quality's World Conference on Quality and Improvement in Nashville, TN. The ASQ conference is a great opportunity to see how quality professionals are tackling problems in every industry, from beverage distribution to banking services.  Given my statistical bent, I like to see how companies apply tools like ANOVA, regression, and especially... Continue Reading
It’s usually not a good idea to rely solely on a single statistic to draw conclusions about your process. Do that, and you could fall into the clutches of the “duck-rabbit” illusion shown here: If you fix your eyes solely on the duck, you’ll miss the rabbit—and vice-versa. If you're using Minitab Statistical Software for capability analysis, the capability indices Cp and Cpk are good examples of... Continue Reading
Many of the things you need to monitor can be measured in a concrete, objective way, such as an item's weight or length. But, many important characteristics are more subjective, such as the collaborative culture of the workplace, or an individual's political outlook. A survey is an excellent way to measure these kinds of characteristics. To better understand a characteristic, a researcher asks... Continue Reading
A while back, I offered an overview of process capability analysis that emphasized the importance of matching your analysis to the distribution of your data. If you're already familiar with different types of distributions, Minitab makes it easy to identify what type of data you're working with, or to transform your data to approximate the normal distribution. But what if you're not so great with... Continue Reading
A few times a year, the Bureau of Labor Statistics (BLS) publishes a Spotlight on Statistics Article. The first such article of 2015 recently arrived, providing analysis of trends in long-term unemployment.  Certainly an interesting read on its own, but some of the included data gives us a good opportunity to look at how thought can improve your regression analysis. Fortunately, Minitab Statistical... 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
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
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
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
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
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
by Lion "Ari" Ondiappan Arivazhagan, guest blogger.  An alarming number of borewell accidents, especially involving little children, have occurred across India in the recent past. This is the second of a series of articles on Borewell accidents in India. In the first installment of the series, I used the G-chart in Minitab Statistical Software to predict the probabilities of innocent children... 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
One of my favorite bloggers about the application of statistics in health care is David Kashmer, an MD and MBA who runs and writes for the Business Model Innovation in Surgery blog. If you have an interest in how quality improvement methods like Lean and Six Sigma can be applied to healthcare, check it out.  A while back, Dr. Kashmer penned a column called "How to Measure a Process When There's... Continue Reading