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Cody Steele

My love for statistics isn’t very common. Even in my own family, the idea of statistics brought frowns to people’s faces. But you don’t have to live in fear of statistics! Continue Reading »

Are you going to be a witch today? Batman? Jedi? You're not alone according to National Retail Federation statistics on top costumes and Halloween spending trends. Last-minute candy shopping? Check out kidzworld.com’s list of the top 10 candies for Halloween. And of course, you have to plan your daily candy consumption to match the limits on free sugar recommended by the World Health Organization... Continue Reading
Control charts are excellent tools for looking at data points that seem unusual and for deciding whether they're worthy of investigation. If you use control charts frequently, then you're used to the idea that if certain subgroups reflect temporary abnormalities, you can leave them out when you calculate your center line and control limits. If you include points that you already know are... Continue Reading
In this day and age, it’s not uncommon that data entry errors occur in data sets that are so large that looking for and correcting the errors by hand is impractical. Fortunately, Minitab includes tools that make it easy to get your data into shape, so that you can proceed to getting the answers you need. Let’s say, for example, that you were going to look at the Global Wood Density Database. It’s... Continue Reading
On the Minitab Blog, we’ve often discussed getting data into Minitab from Excel. Here's a small sampling, in case you currently have data in Excel: Minitab and Excel: Making the (Data) Connection Linking Minitab to Excel to Get Answers Fast 3 Tips for Importing Excel Data into Minitab But if your data is not in Excel to begin with, taking it into Excel to prepare it for entry into Minitab isn’t... Continue Reading
Face it, you love regression analysis as much as I do. Regression is one of the most satisfying analyses in Minitab: get some predictors that should have a relationship to a response, go through a model selection process, interpret fit statistics like adjusted R2 and predicted R2, and make predictions. Yes, regression really is quite wonderful. Except when it’s not. Dark, seedy corners of the data... Continue Reading
The Centers for Medicare and Medicaid Services (CMS) updated their star ratings on July 27. Turns out, the list of hospitals provide a great way to look at how easy it is to get random samples from data within Minitab. Say for example, that you wanted to look at the association between the government’s new star ratings and the safety rating scores provided by hospitalsafetyscore.org. The CMS score... Continue Reading
If you've used our software, you’re probably used to many of the things you can do in Minitab once you’ve fit a model. For example, after you fit a response to a given model for some predictors with Stat > DOE > Response Surface > Analyze Response Surface Design, you can do the following: Predict the mean value of the response variable for new combinations of settings of the predictors. Draw... Continue Reading
It’s not easy to get data ready for analysis. Sometimes, data that include all the details we want aren’t clean enough for analysis. Even stranger, sometimes the exact opposite can be true: Data that are convenient to collect often don’t include the details that we want when we analyze them. Let’s say that you’re looking at the documentation for the National Health and Nutrition Examination Survey... Continue Reading
For one reason or another, the response variable in a regression analysis might not satisfy one or more of the assumptions of ordinary least squares regression. The residuals might follow a skewed distribution or the residuals might curve as the predictions increase. A common solution when problems arise with the assumptions of ordinary least squares regression is to transform the response... Continue Reading
Did you know about the Minitab Network group on LinkedIn? It’s the one managed by Eston Martz, who also edits the Minitab blog. I like to see what the members are talking about, which recently got me into some discussions about Raman spectroscopy data. Not having much experience with Raman spectroscopy data, I thought I’d learn more about it and found the RRUFFTM Project. The idea is that if you... Continue Reading
If you watched television between 1989 and 1993, then you might have had the chance to see original episodes of the television series Quantum Leap. The premise was that a scientist involved in a time-travel experiment gets sent into the bodies of people from the past and has the opportunity to improve the future with his actions. Most of us might not ever get to do something as dramatic as steal a... Continue Reading
The easiest way to determine the probability of being born on a certain day is to assume that every day of the year has an equal probability of being a birthday. But academic scholarship tends to point to seasonal variation in births. If you average statistics from the United Nations, the seasonality in the United States of America from 1969 to 2013, excluding 1976 and 1977, looks like this: Seeing... Continue Reading
If you follow the news in the United States then you’ve heard that there’s a water crisis in Flint, Michigan. Although there’s going to continue to be debate about how much ethics played a role in the data collection practices, it’s worthwhile to at least be ready to perform the correct analysis on the data when you have it. Here’s how you can use Minitab to be like a citizen data scientist... Continue Reading
At the start of a new year, I like to look for data that’s labeled 2016. While it’s not necessarily new for 2016, one of the first data sets I found was healthcare.gov’s data about qualified health and stand-alone dental plans offered through their site. Now, there’s lots of fun stuff to poke around in a data set this size—there are over 90,000 records on more than 140 variables. But to start out I... Continue Reading
Last time, we used factor analysis to come up with factors we could use to describe the performances of Super Bowl-winning quarterbacks. Now, we’ll try to use those factors to compare the performance of our candidate quarterbacks who won at least 3 Super Bowls. Recall that one purpose of factor analysis is to identify underlying factors that you can't measure directly. For example, the members of... Continue Reading
Last time I touched on the subject of the greatest Super Bowl quarterback, I promised a multivariate analysis considering several different statistics. Let’s get right to a factor analysis. Getting Ready for Factor Analysis One purpose of factor analysis is to identify underlying factors that you can’t measure directly. These factors explain the variation of many different variables in fewer... Continue Reading
I generally consider myself old-fashioned. I’m not particularly different on Halloween, where I dress up, pass out candy, sit down in front of the television to watch "It’s the Great Pumpkin, Charlie Brown" on ABC, and read Minitab blog posts from Halloweens past. But some younger folks have told me that I’m missing out, so I’m trying to broaden my horizons to include YouTube. I want to use data... Continue Reading
Part of the fun of sports statistics is that many of the questions are unanswerable in an absolute sense. After a project to improve patient satisfaction scores at a hospital, you can and should measure patient satisfaction scores to determine that the increase met your goals. In sports, we don’t have exact comparisons from player to player, especially when their careers don’t even overlap. Thus,... Continue Reading
September 17 marked the release of new information from the American Community Survey (ACS) from the U.S. Census Bureau. Here’s a bar chart of what the press releases looked like for that day: Clearly there was a theme in play, one that was great news for major metropolitan areas. The Census Bureau even released a graph showing that the percentage of people within the 25 most populous metropolitan... Continue Reading
When I started out on the blog, I spent some time showing some data sets that would be easy to illustrate statistical concepts. It’s easier to show someone how something works with something familiar than with something they’ve never thought about before. Need a quick illustration to share with someone about how to summarize a variable in Minitab? See if they have a magazine on their desk, and... Continue Reading