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Using Probability Plots to Understand Laser Games Scores

There is more than just the p value in a probability plot—the overall graphical pattern also provides a great deal of useful information. Probability plots are a powerful tool to better understand your data.

In this post, I intend to present the main principles of probability plots and focus on their visual interpretation using some real data.

In probability plots, the data density distribution is transformed into a linear plot. To do this, the cumulative density function (the so-called CDF, cumulating all probabilities below a given threshold) is used (see the graph below). For a normal...

Common Statistical Mistakes You Should Avoid

It's all too easy to make mistakes involving statistics. Powerful statistical software can remove a lot of the difficulty surrounding statistical calculation, reducing the risk of mathematical errors—but  correctly interpreting the results of an analysis can be even more challenging. 

No one knows that better than Minitab's technical trainers. All of our trainers are seasoned statisticians with years of quality improvement experience. They spend most of the year traveling around the country (and around the world) to help people learn to make the best use of Minitab software for analyzing data...

More "Hidden Helpers" in Minitab Statistical Software

In an earlier post, I shared some great hidden helpers in Minitab Statistical Software that even many veteran users don't know about. Here are a few more!

Everything In Its Right Place

Minitab’s Project Manager allows you to navigate, view, and manipulate various parts of your project. Right-clicking either the folders or their contents lets you access a variety of menus that allow you to manage Session Window output, graphs, worksheets, command language, and related project areas. You can also copy any or all analyses and graphs to Minitab’s built-in ReportPad to create reports and share your...

I Think I Can, I Know I Can: A High-Level Overview of Process Capability Analysis

Remember "The Little Engine That Could," the children's story about self-confidence in the face of huge challenges? In it, a train engine keeps telling itself "I think I can" while carrying a very heavy load up a big mountain. Next thing you know, the little engine has done it...but until that moment, the outcome was uncertain.

It's a wonderful story for teaching kids about self-confidence. But from a quality and customer service viewpoint, it's a horror story: if your business depends on taking the load up the hill, you want to know you can do it.

That's where capability analysis comes in. 

When...

Creating a Custom Report using Minitab, part 2

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 Word.
  • Highlight a section of the document where you would like to place the created Minitab graph or statistic.
  • Go to the Insert tab, click the Bookmark link, and type in the name of what you will be...

Creating a Custom Report using Minitab, part 1

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 save a lot of time by eliminating the need to recreate the wheel every time management wants a current report. 

I’m going to tell you how to use Minitab Statistical Softwareto automatically generate a...

Using Statistics to Show Your Boss Process Improvements

Ughhh... your process is producing some parts that don't meet your customer's specifications! Fortunately, after a little hard work, you find a way to improve the process.

However, you want to perform the appropriate statistical analysis to back up your findings and make it easier to explain the process improvements to your boss. And it's important to remember that your boss is much like the boss in Eston's posts -- he's not too familiar with statistics, so you'll have to take it slow and show lots of "visual aids" in your explanation. How should you begin? 

Enter before-and-after process...

How to Handle Extreme Outliers in Capability Analysis

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 and non-normal distributions are not good approaches for data that contain extreme outliers.

As an example, the four graphs below show distribution fits for a dataset with 99 values simulated from a...

Is Your Statistical Software FDA Validated for Medical Devices or Pharmaceuticals?

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 certification process to achieve FDA software validation. It's simply not true.

Software vendors who claim their products are FDA-validated should be scrutinized. It is up to the software purchaser to...

Applying Six Sigma to a Small Operation, Part 2

In my previous post, I shared a case study of how a small bicycle-chain manufacturing company in India used the DMAIC approach to Six Sigma to reverse declining productivity.

After completing the Define, Measure, and Analysis phases, the team had identified the important factors in the bushing creation process. Armed with this knowledge, they were now ready to make some improvements.

The Improve Phase

In the Improve phase, the team applied a statistical method called Design of Experiments (DOE) to optimize the important factors they'd identified in the initial phases.

Most of us learn in school...

Applying Six Sigma to a Small Operation

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 methods to save millions of dollars, slash expenses, and improve quality...but when they read about the big dogs getting those kind of results, a lot of folks hear a little voice in their heads...

Process Capability Statistics: Cp and Cpk, Working Together

Capability statistics are wonderful things. These statistics tell you how well your process is meeting the specifications that you have. But there are so many capability statistics that it's worth taking some time to understand how they’re useful together.

Two capability statistics that are hard to keep straight are Cp and Cpk. Their names are different by only a single letter. A single letter that, by the way, doesn’t really explain anything about how these two statistics are different.

Definition of Cp

The equation for Cp is often written ET / NT. ET stands for Engineering Tolerance, which is...

Using Minitab Statistical Software to Analyze the Woeful Bengals

by Jeff Parks, guest blogger

Being a Cincinnati Bengals fan is tough. It's true that Bengals fans don't have it as bad as, say, long-suffering Chicago Cubs fans...nevertheless, the Bengals haven’t won a playoff game since January 1991. That's currently the longest streak in the NFL. In the 1990s they were voted the worst sports franchise by ESPN. Not the worst football team, mind you, but the worst franchise in all of sports.

Not the L.A. Clippers. Not the Cleveland Browns. Not the Pittsburgh Pirates.

The Cincinnati Bengals.

Why? Why must it be so? What separates the Bengals from the good teams in...

How Lean Six Sigma Students at Rose-Hulman Reduced Food Waste

To promote ethical and moral responsibility in shaping its graduates, Rose-Hulman Institute of Technology created a sustainability initiative to reduce its own environmental footprint.

As part of that team's efforts, Six Sigma students at Rose-Hulman conducted a project to reduce food waste at the campus dining center. We got the opportunity to learn more about the project by talking with Dr. Diane Evans, a Six Sigma black belt and associate professor of mathematics at Rose-Hulman who led the students’ efforts, and Neel Iyer, a mechanical engineering student who was also on the project team.

Calc...

Quality Improvement in Healthcare: Completing Projects with DMAIC

The DMAIC methodology for completing quality improvement projects divides project work into five phases: define, measure, analyze, improve, and control. It’s also probably the most well-known and most used project methodology for projects that focus on improving an existing process. (Many other methodologies exist, such as DMADV, which focuses on using quality improvement techniques to create a new product of process design.)

Franciscan Hospital for Children, a hospital in Brighton, Mass., that specializes in the care of children with special health care needs, recently completed a project...

Studying Old Dogs with New Statistical Tricks: Bone-Cracking Hypercarnivores and 3D Surface Plots

A while back my colleague Jim Frost wrote about applying statistics to decisions typically left to expert judgment; I was reminded of his post this week when I came across a new research study that takes a statistical technique commonly used in one discipline, and applies it in a new way. 

The study, by paleontologist Zhijie Jack Tseng, looked at how the skulls of bone-cracking carnivores--modern-day hyenas--evolved. They may look like dogs, but hyenas in fact are more closely related to cats. However, some extinct dog species had skulls much like a hyena's. 

Tseng analyzed data from 3D...

Normal: The Kevin Bacon of Distributions

When you learned statistics, most of what you learned was centered around the Normal distribution.  Maybe you became close friends and you later found out his birth name was Gaussian, but either way you probably just call him Normal.

You might know Normal’s a pretty popular guy with plenty of relationships with other distributions.  There are some obvious connections, like how eNormal is Lognormal, but I thought I’d share some less obvious ones. 

You probably already know that by subtracting his mean and dividing by his standard deviation you get Standard Normal.

What if you squared Standard...

Get Your Way, Every Time: 7 Default Settings in Minitab You Didn’t Know You Could Change

Unless you’re 3 years old, you probably can’t have things just the way you want them all the time.  

You can’t always have peanut butter and ranch dressing on your toast. Or ketchup on your pineapple. Or sugar sprinkles on your peas.

But there is one small arena in life over which you can still exert your control. 

Tools > Options in Minitab's statistical software allows you to change selected default settings in the software, without having to throw a temper tantrum first.

This powerful, underutilized feature in Minitab may save you from the inconvenience of having to change a default setting...

Lightsaber Capability Analysis: The Results

Here at the lightsaber factory, we've completed several steps in doing a capability analysis:

We’re getting close to our deadline, and it’s finally time to carry out our Capability Analysis and see if we are manufacturing our lightsabers to the correct specifications as set forth by the Jedi Temple.

First, let’s go to Stat > Quality Tools > Capability Analysis > Normal.  (If you want to play along and you don't already have it, get the...

Streamlining Surveillance Processes with Lean Six Sigma

I had the privilege of talking with Sue Schlegel, Lean Six Sigma black belt and quality improvement mentor at White Sands Missile Range, which is located just outside of Las Cruces, New Mexico. Schlegel and an improvement team at White Sands recently conducted a Lean Six Sigma project to streamline surveillance processes and they used Minitab to analyze the data. We found Sue’s story an interesting case study for a LSS project, so I thought I would share it with you here on the blog, too.

Reducing Work Hours

When clients request classified video surveillance missions, the White Sands Missile...