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Andy Cheshire

Andy Chesire wrote for the Minitab Blog from 2011-2015.

Don't be a grumpy cat when something on your capability report doesn't smell right. After pressing that OK button to run your analysis, allow your inner cat to understand how and why certain statistics are being used. To help you along, here are some capability issues that customers have brought up recently. Cp is missing You’ve generated a capability analysis report with the Johnson transformation... Continue Reading
It sometimes may be prohibitively expensive or time-consuming to gather data for all runs for a designed experiment (DOE). For example, a 6 factor, 2-level factorial design can entail 64 experimental runs, which may be too high a number for your particular situation. We have seen how to handle these some of these situations in previous posts, such as  Design of Experiments: "Fractionating" and... Continue Reading

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Every now and then I’ll test my Internet speed at home using such sites as http://speedtest.comcast.net.  My need to perform these tests could stem from the cool-looking interfaces they employ on their site, as they display the results using analog speedometers and RPM meters. They could also stem from the validation that I need in "getting what I am paying for," although I realize that there are... Continue Reading
I recently fielded an interesting question about the probability and survival plots in Minitab Statistical Software's Reliability/Survival menus: Is there a one-to-one match between the confidence interval points on a probability plot and the confidence interval points on survival plot at a specific percentile? Now, this may seem like an easy question, given that the probabilities on a survival plot... 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 1898, Russian economist Ladislaus Bortkiewicz published his first statistics book entitled Das Gesetz der keinem Zahlen, in which he included an example that eventually became famous for illustrating the Poisson distribution. Bortkiewicz researched the annual deaths by horse kicks in the Prussian Army from 1875-1984. Data was recorded from 14 different army corps, with one being the Guard... 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
Recently, Minitab’s Joel Smith posted about his vacation and being pooped on twice by birds. Then guest blogger Matthew Barsalou wrote a wonderful follow-up on the chances of Joel being pooped on a third time. While I cannot comment on how Joel has handled this situation psychologically so far, I can say that if I had been pooped on twice in a short amount of time, I would be wary of our... Continue Reading
You may have been in a situation where you had created a general full factorial design and noticed that your design’s run size was higher than you imagined. (Quick refresher: a general full factorial design is an experimental design where any factor can have more than 2 levels). Determined to minimize the monstrous size of your worksheet, you go back to Stat > DOE > Factorial > Create Factorial... Continue Reading
Hi everyone! Over the past month, I fielded some interesting customer calls regarding control chart creation and editing. I wanted to share these potential scenarios with you in hopes that you will find them informative and useful. For these scenarios, I used the XBar-R chart as my template, but you could easily apply them to many of the other control charts in Minitab.  Scenario 1: Create a... Continue Reading
Many statistical analyses require an assumption of normality. In cases when your data are not normal, sometimes you can apply a function to make your data approximately normal so that you can complete your analysis. If you've seen any of the Transformers movies, you know that these extraordinary robots can, with some Hollywood magic, turn themselves into apparently normal items like cars... Continue Reading
Last time, I shared some useful tools for handling date and time data. But Minitab has many other useful tools for manipulating date/time data that you might not be aware of. Let’s take a look at a few more helpful tips and tricks. Extracting Information from a Date/Time Column If you look under the Data menu, you’ll notice Extract from Date/Time > To Numeric or To Text. This function allows you to... Continue Reading
Whether you're a Lean Six Sigma black belt, a researcher, or a statistics student, at some point you will need to work with data that involve either dates, times, or both. Do you know where all of your date/time tools are? Let’s take a quick trip through Minitab Statistical Software and see what it has to offer for date/time data: Column Indicators of Date and Time Data You will know when Minitab... Continue Reading
Coming off an epic season finale of AMC’s The Walking Dead, I thought that zombies might be able to lend a hand in explaining the 2-Sample Poisson Rate test. What Do Zombies Have to Do with the 2-Sample Poisson Rate Test? Let’s say that you and a group of refugees are facing the zombie menace, and an area in which you are camping is soon to be overrun by the undead. In order to know which county to... Continue Reading
Last week, a customer called with an issue related to running a Gage R&R nested design in Minitab Statistical Software.  Everything initially looked okay, as he had the three columns necessary to perform a successful study: one for parts, one for operators, and another for the measurements.  However, when he tried to analyze his data using Stat > Quality Tools > Gage Study > Gage R&R (Nested), he... Continue Reading
Groundhog Day is apparently a pretty big deal in Punxsutawney, Pennsylvania. According to one CBS article, organizers expected over 15,000 people to see the United States’ most popular groundhog last week.For those unfamiliar with the legend, here's the idea: If Punxsutawney Phil sees his shadow after coming out of his hole, he will retreat and we will be forced to endure six more weeks of winter.... Continue Reading
I recently received questions about creating bar charts within Minitab and thought I'd share some information about this common task on the blog. When creating a bar chart in Minitab, you begin by going to Graph > Bar Chart. This brings up a dialog box:    The next step can prove quite vexing. In the dialog box, it can be tempting to quickly select the picture that best represents what you want... Continue Reading
I want to offer some clarification on my earlier blog about Cluster Analysis. There may have been some confusion as to what the four dendrograms were trying to display in my prior post. The first dendrogram in the four-graph layoutrepresented the final partition if the user chose only one cluster. If the user chose the final partition to be four clusters, the end result would be the last graph in... Continue Reading
Cluster Analysis aims to establish a set of clusters such that cases within a cluster are more similar to each other than are cases in other clusters. In other words, we're using data to arrange objects into groups. Arranging objects into groups is a natural skill we all use and share.In life, we use an item’s characteristics or traits to determine what group to throw them in.  In Cluster... Continue Reading
It looks like I may have gotten my wish: NBA games should start Christmas day, which will be a huge present to a lot of fans. So while I ponder whether to proceed with a second post about statistics related to the lockout, let's shed some light on a different subject. From time to time, Minitab users will call in needing assistance with control charts.  One common problem people encounter... Continue Reading