E6S-047 Variations - Part 1

Intro:  Welcome to the E6S-Methods podcast with Jacob and Aaron, your source for expert advice on Lean, Six Sigma, and performance improvement methods. In this episode number 47, “Variations” Part 1, we introduce the critical concept of variation and the normal distribution.  Here we go.

Objection 1:  These are simple terms. Everyone knows this stuff.                                                                         

Counter: Perhaps. But it requires covering just to get everyone on the same page.                                                                                                                                                                                                        

I            Where are we going with this?

a.       In order to understand Measurement System Variation, you first need an appreciation for normal variation and different types of distributions that exist

b.      All sample (from process or population) variation is a combination of the tendencies of the population as well as variation tendencies of the measurement system.  Measurement system variation is an artifact imposed on the sample, and thus the population as a result of trying to measure it.            

II         Describing a Distribution

a.       Location: Central Tendency  

i.      Main Measures

1.      Mean – Arithmetical “average” – (sum of values)/(count of values)

2.      Median – The midpoint, when data is arranged in numerical order

3.      Mode – most frequently occurring value (highly dependent on precision of the value)

ii.      Dangers - (only tells a small part of the story)

1.      Too many businesses focus on the mean of business metrics, and ignore the variation, and get a false sense of success.  The customer feels the variation.

a.       Two Statisticians go hunting.  To better their chances, they shoot at the same time.  One misses 10 feet to the left, the other misses 10 feet to the right.  They stand and high-five each-other, knowing “on average” they made the kill.

b.      Put your head in and oven, and your feet in a freezer.  On average your temperature is normal 

b.      Spread

i.      Main Measures

1.      Standard Deviation – The “average” distance each point is from the mean (geometrical average)

2.      Variance – Square of Standard Deviation

3.      Range – Difference between the maximum value and the minimum value  

ii.      Dangers – Most meaningful when combined with  a location measurement (i.e. mean)           

Outro: Thanks for listening to episode 47 of the E6S-Methods Podcast.  Stay tuned for episode number 48 where we finish of the theme of variations and distribution. Subscribe to past and future episodes on iTunes or stream us live on-demand with Stitcher Radio. Have an idea for an episode? Contact us!  Follow us on twitter @e6sindustries. Join a discussion on LinkedIn. Find outlines and graphics for all shows and more at www.E6S-Methods.com. “Journey Through Success”