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Use a Line Plot to Show a Summary Statistic Over Time

If you’re already a strong user of Minitab Statistical Software, then you’re probably familiar with how to use bar charts to show means, medians, sums, and other statistics. Bar charts are excellent tools, but traditionally used when you want all of your categorical variables to have different sections on the chart. When you want to plot statistics with groups that flow directly from one category to the next, look no further than Minitab’s line plots. I particularly like line plots when I want to use time as a category, because I prefer the connect line display to separated bars.

I like to...

Enhancing Weekly Productivity with Staged Control Charts

by The Discrete Sharer, guest blogger

As Minitab users, many of us have found staged control charts to be an effective tool to quantify and demonstrate the “before and after” state of our process improvement activities.

However, have you ever considered using them to demonstrate the effects of changes to compensation/incentive plans for your employees? 

Here's an example of how a mid-sized commercial bank used Minitab’s staged control charts to better inform senior leaders about the benefits of an pilot incentive plan program, in the hopes of having it implemented nationwide.

Background

Because...

How Could You Benefit from Plackett & Burman Experimental Designs ?

Screening experimental designs allow you to study a very large number of factors in a very limited number of runs. The objective is to focus on the few factors that have a real effect and eliminate the effects that are not significant. This is often the initial typical objective of any experimenter when a DOE (design of experiments) is performed.

Table of Factorial Designs

Consider the table below. In Minitab, you can quickly access this table of factorial designs by selecting Stat > DOE > Factorial > Create Factorial Design... and clicking "Display Available Designs." The table tells us the...

3 Things Baseball Can Teach Us About Control Charts

Control charts are some of the most useful tools in statistical science. They track process statistics over time and detect when the mean or standard deviation change from what they have been. The signals that control charts send about special causes can help you zero in on the fastest ways to improve any process, whether you’re making tires, turbines, or trying to improve patient care.

I’ve mentioned before that I’m a baseball fan. For the past several years, I’ve been noticing articles about the Year of the Pitcher in Major League Baseball (2010, 2011, 2012, 2013, 2014). That repetition...

Quality Improvement in Healthcare: Showing if process changes actually improve the patient experience

Via Christi Health, the largest provider of healthcare in Kansas, operates a Center for Clinical Excellence that's made up of a team of quality practitioners, all who have Lean and Six Sigma training. I recently had the opportunity to talk with the team about the types of projects they're working on.

I learned not only about the areas of patient care where they are targeting improvements, but about one particular project the team completed to determine if process changes put into place in the hospital's emergency department actually improved the patient experience.

I thought it was an...

The Five Coolest Things You Can Do When You Right-click a Graph in Minitab Statistical Software

Minitab graphs are powerful tools for investigating your process further and removing any doubt about the steps you should take to improve it. With that in mind, you’ll want to know every feature about Minitab graphs that can help you share and communicate your results effectively. While many ways to modify your graph are on the Editor menu, some of the best features become available when you right-click your graph.

Here are the five coolest things you can do when you right-click a graph in Minitab Statistical Software.

Send graph to...

Once your graph is ready for your report or presentation,...

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...

A Little Trash Talk: Improving Recycling Processes at Rose-Hulman

The Six Sigma students at Rose-Hulman Institute of Technology are at it again! A few months back, we blogged about the Six Sigma project they did to reduce food waste at the on-campus dining center.

This time, the students—lead by Dr. Diane Evans, Six Sigma black belt and associate professor of mathematics at Rose-Hulman—are performing a Lean Six Sigma project to reduce the amount of recycling thrown in the normal trash cans in all of the institution's academic buildings, including the library. Unfortunately, the recycling bins Rose-Hulman has placed all over its campus are underused, and it’s...

“Hello, How Can I Help You?”- A Look at Quality Improvement in Financial Services

It’s common to think that process improvement initiatives are meant to cater only to manufacturing processes, simply because manufacturing is where Lean and Six Sigma began. However, many other industries, in particular financial services and banking, also rely on data analysis and Lean Six Sigma tools to improve processes.

Rod Toro is a business process improvement manager at Edward Jones, and I recently got the chance to talk with him about a Lean Six Sigma project the service division at his company completed to improve customer satisfaction.

Edward Jones has been increasing the number of...

ITEA Sneak-Peek: The Great Escape from Foam Defects

The 2014 ASQ World Conference on Quality and Improvement is coming up in early May in Dallas, and this year’s International Team Excellence Award Process (ITEA) will also come to a close at the conference, as winners from the finalist teams will be chosen for ASQ gold, silver, or bronze-level statuses.

What’s ITEA?

The annual ASQ ITEA process celebrates the accomplishments of quality improvement teams from a broad spectrum of industries from around the world. The ITEA is the only international team recognition process of its kind in the United States, and since 1985, more than 1,000 teams from...

Equivalence Testing for Quality Analysis (Part I): What are You Trying to Prove?

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 has already been through the regulatory approval process.

But in the field of quality improvement, why might you want to use an equivalence test instead of a standard t-test?

Interpreting Hypothesis...

The Best European Football League: What the CTQ’s and Minitab Can Tell Us

by Laerte de Araujo Lima, guest blogger

In a previous post (How Data Analysis Can Help Us Predict This Year's Champions League), I shared how I used Minitab Statistical Software to predict the 2013-2014 season of the UEFA Champions league. This involved the regression analysis of main critical-to-quality (CTQ) factors, which I identified using the “voice of the customer” suggestions of some friends.

Since that post was published, my friends have stopped discussing the UEFA Champions league—they were convinced by the results I shared.

But now they’ve challenged me to use Six Sigma tools to...

Control Chart Tutorials and Examples

The other day I was talking with a friend about control charts, and I wanted to share an example one of my colleagues wrote on the Minitab Blog.  Looking back through the index for "control charts" reminded me just how much material we've published on this topic.

Whether you're just getting started with control charts, or you're an old hand at statistical process control, you'll find some valuable information and food for thought in our control-chart related posts. 

Different Types of Control Charts

One of the first things you learn in statistics is that when it comes to data, there's no...

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...

Got Good Judgment? Prove It with Attribute Agreement Analysis

Many Six Sigma and quality improvement tools could be applied in other areas. For example, I wonder whether my son's teachers could benefit from a little attribute agreement analysis. 

He seemed frustrated the other day when I picked him up at school. He'd been working on a presentation that needed to be approved by his teachers. (My son attends a charter school, and each class is taught by a two-person teaching team.)

"What's wrong?" I asked when he clambered into the car with a big sigh.

My son explained that he'd given the presentation to teacher Jennifer that morning. A few minor suggestions...

Re-analyzing Wine Tastes with Minitab 17

In April 2012, I wrote a short paper on binary logistic regression to analyze wine tasting data. At that time, François Hollande was about to get elected as French president and in the U.S., Mitt Romney was winning the Republican primaries. That seems like a long time ago…

Now, in 2014, Minitab 17 Statistical Software has just been released. Had Minitab 17, been available in 2012, would have I conducted my analysis in a different way?  Would the results still look similar?  I decided to re-analyze my April 2012 data with Minitab 17 and assess the differences, if there are any.

There were no...

The Stability Report for Control Charts in Minitab 17 includes Example Patterns

Minitab’s Assistant got a lot of splashy upgrades for Minitab 17. The addition of DOE and multiple regression to the Assistant are large feature improvements with obvious advantages. But there are many subtler, but still fantastic additions that shouldn't be overlooked.

One of those additions is the example patterns added to the Stability Report for control charts.
 
The Stability Report was excellent in Minitab 16, clearly showing you the out-of-control points in the process:

But the truth is that it’s sometimes hard to move from detecting the out-of-control points to an understanding of what’s...

Say "I Love You" with Data on Valentine's Day

When we think about jobs with a romantic edge to them, most of us probably think of professions that involve action or danger.  Spies, soldiers, cops, criminals -- these are types of professions romantic leads have. Along with your occasional musician, reporter, or artist, who don't have the action but at least bring drama.

But you know who never shows up as a romantic lead?  Quality improvement professionals, that's who.  Can you name just one movie that features a dedicated data analyst or quality practitioner as the love interest...just one?  No, you can't.  Doesn't exist.

Love of Quality:...