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Case Studies/Articles

by Philip Mayfield


Were the Colts' footballs below the required 12.5 psi?

The Patriots were recently fined $1 million, lost two draft picks, and lost Tom Brady for four games. The NFL's motivation was that the Patriots' footballs were deflated to a pressure outside the acceptable range of 12.5 to 13.5 psi. Given the data that was recorded at halftime, a very good argument can be made that the Colts' footballs were also outside of the acceptable range. Thus, if the NFL is ready to penalize the Patriots, what about the Colts?



Can the NFL Measure the Pressure of Footballs Precisely?

Deflategate has been in the news extensively in the past few months. The Ted Wells report includes 139 pages of text messages, rules, and data which delves into the hypothesis that the Patriots were responsible for deflating the footballs. Attached to the report is a 68 page Lab analysis which is used to support the hypothesis.  


According to the Wells report, "Rule 2 of the Official Playing Rules of the NFL requires footballs used during NFL games must be inflated to between 12.5 and 13.5 psi." Does the NFL's measurement system have the precision required to measure footballs in this range?



Quantum XL 2013 New Features

With the addition of Design of Experiments (DOE) functionality to the 2013 release, Quantum XL obtains an unprecedented state in the market. In one application, you can find statistical analysis, DOE, Monte Carlo Simulation, and companion tools (QFD, FMEA, Pugh).


Design of Experiments (DOE) Tutorial with Quantum XL

In this tutorial we will lead you through the process of setting up a DOE, analyzing it with regression/ graphical tools, and optimizing the output.


Categorical Predictor Variables in Design of Experiments (DOE)

Most regression text and classes are taught with the inputs (Xs) all being quantitative. However, in the real world, sometimes inputs are categorical. Most regression software, such as Quantum XL, handles categorical inputs with predictor or dummy variables.


Mixed Response Modeling with Quantum XL 2013

With Quantum XL we've simplified the modeling of categorical inputs, different types of outputs, and multiple responses.


Logistic Regression Case Study

Did Performance-Enhancing Drugs Favor Batters or Pitchers?


FlexWedge for Automated Data Entry to Excel

If you're tired of typing data into Excel, then I have a potential solution. MidWestFlex has created a small device called "FlexWedge" which captures data from gauges and enters it into Excel automatically.


Moving beyond the t/F test

If you are new to hypothesis testing, check this article on how to select the correct hypothesis test.


Quantum XL's Auto-Hypothesis Test

With the release of Quantum XL 2012, we introduced a Hypothesis AutoTest capability. This feature analyzes various statistics of your dataset and endeavors to perform the appropriate hypothesis test for Mean/Median and Variation. 


How Hertz is Running with Scissors

The elusive Voice of the Customer (VOC), read how Hertz found it and then summarily destroyed it with a branch of their flowchart.

Lettuce Head

Using the Paired t-Test to  compare Wegmans and Publix Supermarkets

The Paired t-Test is a hypothesis test that can be used when certain conditions are satisfied. In this article, I  compare prices of two different supermarkets to determine if a difference in price exists. In the article, I explain the requisite conditions to use the Paired t-Test and contrast it with the unpaired (or normal) t-Test.


Using Kano’s Model to Understand and Set Customer Expectations

Kano’s model is a tool commonly used to understand different types of quality and customer expectations. This article serves as an introduction using the cruise industry as an example.

latitude plot

Latitude Plots

Quantum XL's Latitude Plots are a visual depiction of the relationship between the expected variation and the latitude window.


Optimization using Quantum XL

Quantum XL's optimizer provides the unique ability to minimize the defects per million (dpm) across multiple outputs in a model. The optimization is a true stochastic optimization, which means that the inputs are all modeled with probability distributions.


Using Quantum XL to Define Multiple Inputs Simultaneously

In 1927, Babe Ruth hit 60 home runs, setting the single season record that would stand for more than three decades. Thirty four years later, in 1961, Roger Maris surpassed Babe Ruth with 61 home runs.


Simple Monte Carlo

Quantum XL has been enhanced to support a number of new features. The most significant new feature is the ability for any cell to be an input and any cell to be an output.

Flower lessons

Design for Lean Six Sigma Deployment Book

Thinking about rolling out a Design for Lean Six Sigma program to your product development organization? Not sure where to start or how to help ensure a successful deployment? A recently published book may give you insight into a successful DFSS deployment.


Quantum XL 2009 New Features

DFSS XL 2008 has been renamed Quantum XL 2009. It is in final beta and should launch in the Q1 2009. The new version includes numerous new features including more flexible model building, latitude plots, percent contribution plots, support for 13 distributions, and much more.


Scatter Plots and Simple Linear Regression

A scatter diagram is an extremely simple statistical tool used to show a relationship between two variables. It is often combined with a simple linear regression line used to fit a model between the two variables. To illustrate this, I collected some data on a recent trip to the La Brea Tar Pits.


Understanding Binomial Confidence Intervals

The Binomial Distribution is commonly used in statistics in a variety of applications. There are several ways to estimate the Binomial Confidence Interval (CI); in this article we will focus on the Normal Approximation Method and the Clopper-Pearson Method.


Introduction to FMEA on a Ski-Resort Gondola Lift

I was suspended approximately 200 feet above a ravine when the thought occurred to me. Had the engineer(s) of the Gondola Lift that my family and I were currently occupying used Failure Mode and Effects Analysis (FMEA) when designing the lift?


Roger Clemens, Barry Bonds, Performance-Enhancing Drugs, and a Hypothesis Test

Athletes and their purported use of performance-enhancing drugs have dominated the sporting news in the last few months. The controversy seems to be particularly heated in the sport of baseball, with the Mitchell Report naming many famous players. Of particular interest is the accusation by Brian McNamee that Roger Clemens used performance-enhancing drugs to increase his performance.


Calculating Type I Probability - Article covering the math details behind the article Roger Clemens and a Hypothesis Test.


Potato Cannons and the Taguchi L12

In the week between Christmas and New Year's Eve 2007, I found myself with a nearly empty golf course, beautiful central Florida weather, ample free time with my children, and a potato cannon.


Tennis Ball Cannon Velocity and a Full Factorial

Abraham Lincoln's son Tad had a toy cannon which, according to folklore, he fired on the Cabinet after receiving a pretend military commission. Tad's cannon is currently ...


Family Vacations and QFD

Many people who have heard of QFD (Quality Function Deployment) would like to understand more about this powerful tool. This article serves as an introduction to the basics to get you started.