Total 19 Posts

# Taguchi Loss Function

Saying the words “Genichi Taguchi” to a hard core “western statistician” may get you some dirty looks. Actually, some of these crazy statisticians may want to strike you for saying this person’s name. Why the hate you may ask?  Good question. Let me give you my take on it. Genichi

# Span – GE’s Variation Weapon

GE is arguably one of the best examples of Six Sigma excellence today. An often heard phrase is, “Motorola invented Six Sigma and GE perfected it.”A slick “variation weapon” GE has developed is called Span. I have never worked for GE but have worked with many former GE employees who

# Explaining Cp and Cpk

When we speak about the capability of processes we often refer to a couple indices called Cp and Cpk. These two indices, used together, can tell us how capable our process is and whether or not we have a centering issue.  For the math geeks out there here are the

# Demystifying Design of Experiments

I love Design of Experiments (DOE). Over the years I have done my fair share of them – everything from simple 2^2 full factorial designs to your more complicated Response Surface Methodology designs. Tonight I want to start by explaining what DOE’s are and what they are not. I will

# Regression – Part 3

This evening we will wrap up our discussion of regression. So far we have discussed what regression is and a few ways to determine whether our model is significant. Next up I want to discuss something called the least squares method and residuals. I will wrap it all up with

# Hypothesis Testing

One of my favorite statistical tools is hypothesis testing. We can use hypothesis testing for many purposes. For example, we would use the popular 2-sample t-test when we have two samples of variable data and want to understand if they represent different populations, statistically speaking of course. State the Null

# Control Charts – Part 3

Hello friends! This is the 3rd and final installment of all you wanted to know about control charts but were afraid to ask. In part 1 of the series we talked about the history and purpose of control charts. In part 2 we discussed three different control charts that are

# The Heated Law of Dispersion

One debate that often arises amongst my Six Sigma cohorts is when to use the standard deviation of a dataset and when we should use another measure of dispersion, namely the range. Descriptive Statistics Overview Let’s take a quick review from our descriptive statistics class. When we are looking at

# Process Mapping – Lean or Six Sigma Tool?

If someone walked up to your this morning at the coffee machine and asked you, “is process mapping a Lean or Six Sigma tool?” what would you say? This may seem like a trivial question but I dare say it is not. Poka-Yoke is a Six Sigma Tool? I remember reading