|
|
 |
Use Standard Deviation to Understand your Process Variation
|
|
|
|
|
|
One of the most important measures of variation is the standard deviation. The standard deviation (s) of a set of sample scores is a measure of variation of scores about the mean, and is defined by the following formula:  Using this formula we can now compare the variation of the two pizza companies and note that the standard deviation for ABC Pizza (0.48 minutes) is much lower than the standard deviation for XYZ Pizza (1.82 minutes). This supports our original observation of the data and our results of the range as a quantification of the variation.
In our definition of standard deviation, we referred to the standard deviation of sample data as s. If we want to calculate the standard deviation ( ) of a population, we would divide by the population size N, instead of n-1. The range may be misleading in this case because it only uses the maximum and minimum data set values. Standard deviation would be a better tools for variation in this case. You can see from these results that the two pizza parlors have the same measures of central tendency, so, on average, customers wait the same amount of time for pizzas at the two restaurants. Based on these measurements alone, we cannot see any distinguishable difference between the two processes. Page 1 > Variation: The Root Of All Process Evil
Page 2 > Range: The Easiest Measure of Variation
Copyright © 2000-2008 iSixSigma – All Rights Reserved
Reproduction Without Permission Is Strictly Prohibited – Copyright Requests
Publish an Article: Do you have a Six Sigma tip, learning or case study?
Share it with the largest community of Six Sigma professionals, and be recognized by your peers.
It's a great way to promote your expertise and/or build your resume. Read more about submitting an article.
"The Bottom Line" Links
|
| |
|
|
BMG
Upgrade Your Skills
|
Master Black Belt Certification
Get the industry's most Flexible, Robust Program for Professionals
>> Find out more
|
|
![]() |
|
|
![]() |
|
SIGMAPRO |
MBB, Lean Sigma, & DFSS
when
experience
matters
most...
|
|
![]() |
M O T O R O L A
U N I V E R S I T Y |
Learn from the most experienced
practitioners of Six Sigma in the world
Public Training & Certification
Click here to take a free Six Sigma Lesson
|
|
![]() |
|
J |
URΛN
| |
Lean Six Sigma Public Workshops
Atlanta, GA - Sept 2008
Become one of your organization's 'vital few'. Get Juran Certified. |
|
|
![]() |
|
LSI
Knowledge & Experience
|
Get Your Lean Black Belt Certification - in Denver
Register Now - Starts August 11!
>>Learn about LodeStar Institute specials..
|
|
![]() |
|
HOWARD UNIVERSITY
Now offering Process Simulation !
4 weeks + 1 cost saving project + 1 mentor + 1 caring instructor = 1 Marketable Certified Lean Six Sigma Black Belt
|
|
![]() |
|
WINSTON SALEM STATE UNIVERSITY
Now offering Process Simulation !
4 weeks + 1 cost saving project + 1 mentor + 1 caring instructor = 1 Marketable Certified Lean Six Sigma Black Belt
|
|
![]() |
THE UNIVERSITY OF
TEXAS
AT AUSTIN |
|
2 weeks + 1 project = Black Belt Certification
|
|
|
![]() |
| . |
Find us on LinkedIn |
Join the iSixSigma Network
and Connect with Other Six Sigma Pros |
|
| . |
|
![]() |
| . |
iSixSigma Live! Summit & Awards
Jan 13-16, 2009 • Miami, FL |
Save up to $700 • Click Here!
Register by August 14 |
|
| . |
|
Download the iSixSigma Toolbar for 1-Click access. Search Your Way. Everyday. Without Delay.
|
|
|
