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T-Test Example

Blog posts and articles about testing hypotheses with the statistical method called the T-Test.

With more options, come more decisions. With equivalence testing added to Minitab 17, you now have more statistical tools to test a sample mean against target value or another sample mean. Equivalence testing is extensively used in the biomedical field. Pharmaceutical manufacturers often need to test whether the biological activity of a generic drug is equivalent to that of a brand name drug that... Continue Reading
Now that you’ve seen how to automatically import data and run analyses in my previous post, let’s create the Monthly Report! I will be using a Microsoft Word Document (Office 2010) and adding bookmarks to act as placeholders for the Graphs, statistics, and boilerplate conclusions. Let’s go through the steps to accomplish this: Open up an existing report that you have previously created in Microsoft... Continue Reading
As a member of Minitab’s Consulting and Custom Development Services team, I get to help companies across a variety of industries create many different types of reports for management. These reports often need to be generated weekly or monthly. I prefer to automate tasks like this whenever possible, so that new or updated reports can be created without much effort. A little investment up front can... Continue Reading
Back in November, I wrote about why running the football doesn’t cause you to win games in the NFL. I used binary logistic regression to look at the relationship between rush attempts (both by the lead rusher and by the team) and wins. The results showed that the model for rush attempts by the lead rusher and wins fit the data poorly. But the model for team rush attempts and wins did fit the data... Continue Reading
Transformations and non-normal distributions are typically the first approaches considered when the when the Normality test fails in a capability analysis. These approaches do not work when there are extreme outliers because they both assume the data come from a single common-cause variation distribution. But because extreme outliers typically represent special-cause variation, transformations... Continue Reading
We're frequently asked whether Minitab has been validated by the U.S. Food and Drug Administration (FDA) for use in the pharmaceutical and medical device industries. Minitab does extensive testing to validate our software internally, but Minitab’s statistical software is not—and cannot be—FDA-validated out-of-the-box. Nobody's can. It is a common misconception that software vendors can go through a... Continue Reading
Have you ever wished your control charts were better?  More effective and user-friendly?  Easier to understand and act on?  In this post, I'll share some simple ways to make SPC monitoring more effective in Minitab. Common Problems with SPC Control Charts I worked for several years in a large manufacturing plant in which control charts played a very important role. Virtually thousands of SPC... Continue Reading
Today our company is introducing Minitab 17 Statistical Software, the newest version of the leading software used for quality improvement and statistics education.   So, why should you care? Because important people in your life -- your co-workers, your students, your kids, your boss, maybe even you -- are afraid to analyze data.   There's no shame in that. In fact, there are pretty good reasons for... Continue Reading
Using data analysis and statistics to improve business quality has a long history. But it often seems like most of that history involves huge operations. After all, Six Sigma originated with Motorola, and became adopted by thousands of other businesses after it was adopted by a little-known outfit called General Electric. There are many case studies and examples of how big companies used Six Sigma... Continue Reading
Everyone loves Minitab’s Assistant. My favorite bit, as I’ve shown with the Gage R&R Study, is the way that the Assistant puts all the results you need into reports that are easy to understand and present. But it’s also pretty neat that before you ever choose what to do in Minitab, the Assistant is ready to help you. Let’s take a closer look at the Assistant's Graphical Analysis tools. Help Me... Continue Reading
If you regularly perform regression analysis, you know that R2 is a statistic used to evaluate the fit of your model. You may even know the standard definition of R2: the percentage of variation in the response that is explained by the model. Fair enough. With Minitab Statistical Software doing all the heavy lifting to calculate your R2 values, that may be all you ever need to know. But if you’re... Continue Reading
I’ve written a number of blog posts about regression analysis and I think it’s helpful to collect them in this post to create a regression tutorial. I’ll supplement my own posts with some from my colleagues. This tutorial covers many aspects of regression analysis including: choosing the type of regression analysis to use, specifying the model, interpreting the results, determining how well the... Continue Reading
by Arun Kumar, guest blogger One of the most commonly used statistical methods is ANOVA, short for “Analysis of Variance.” Whether you’re analysing data for Six-Sigma styled quality improvement projects, or perhaps just taking your first statistics course, a good understanding of how this technique works is important. A lot of concepts are involved in any analysis using ANOVA and its subsequent... Continue Reading
Applied regression analysis can be a great decision-making tool because you can predict the average outcome given input values. However, predictions are not as simple as plugging numbers into an equation. In my previous post I showed how a majority of experts vastly underestimated the variability around the predicted outcome in a manner that can lead to costly mistakes. We also saw how graphing the... Continue Reading
A colleague of mine at Minitab, Cheryl Pammer, was recently featured in "A Statistician's Journey," a monthly feature that appears in the print and online versions of the American Statistical Association's AMSTAT News magazine.   Each month, the magazine asks ASA members to talk about the paths they took to get to where they are today. Cheryl is a "user experience designer" at Minitab. In other... Continue Reading
What do you see when you look at the image at right? Do you see a bulging sphere that stretches the checkerboard pattern in the center, causing its lines to curve? Are you sure? Look again. This time, test any “curved” line by holding a straightedge next to it. The image is actually composed of small squares and straight lines. Yet, when perceived as a composite whole, it creates a completely... Continue Reading
When I first got interested in looking at baseball park factors, I only wanted to know which parks benefited hitters and which benefited pitchers. Once I got started, I got interested in the difference between ESPN's published formula and its results and whether there were obvious reasons for the variation in park factors from year-to-year. But today I’m returning to the original question: which... Continue Reading
Recently, a customer called our Technical Support team about a Design of Experiment he was performing in Minitab Statistical Software. After they helped to answer his question, the researcher pointed our team to an interesting DOE he and his colleagues conducted that involved using nasal casts to predict the drug delivery of nasal spray. The study has already been published, and you can read... Continue Reading
Ever start a fantasy football draft and realize that passing touchdowns are worth 6 points, not 4? Or how about realizing at the last minute that the commissioner of your league decided to have a point per reception (PPR) league. We know that this year running backs are going to be going early in the draft. But if your league is a PPR or gives 6 points for a passing touchdown, should you... Continue Reading
by Cory Heid, guest blogger A few months ago I posted a blog about Tootsie Pops and how many licks it takes to get to the Tootsie Roll center. If you haven’t read the post, here's a quick summary. Recap of Initial Study I broke down my experiment into four parts where I would test: the force of a lick temperature of a person's mouth pH level of a person's saliva the solubility of a person's saliva After... Continue Reading