Online Statistics Textbooks (@)
1.5 Sigma Process Shift Explanation
Why is 6 sigma 3.4 ppm, not 2 ppb? The calculation of process sigma after a process improvement project should be reported as short-term sigma. This article explains why and how to perform the calculation. From iSixSigma.
50% Sampling Savings With Sequential Test Method
Using Wald's Sequential Test Method for process capability decisions can result in 50% sampling savings. Sequential Testing can also be automated, enhanced and extended to the Binomial, Poisson and Reliability Test areas. From John J. Hickey.
Best Capability Index
Is Cpk the best capability index? From PQ Systems.
Calculating Process Efficiency in Transactional Projects
Principals of Lean Manufacturing are applicable to any business process. This article reviews some of the common problems seen in transactional projects and outlines an example where simple graphical methods are used to interpret cycle time data. From Dr. Alastair Muir and iSixSigma.
Capability Analysis
Great tutorial on capability analysis. What is it, what does it look like, when is it used, how is it made and getting the most from it. From PQ Systems.
Capability And Performance
A great deal of people confused about the important process measure indices of Capability and Performance. Here is an explanation from a Process Development Engineer. From Yuriy Sokolov.
Cpk or Ppk
Confusion over calculating Cpk by two different methods is one reason that a new index, Ppk, was developed. Which should you use? From PQ Systems.
Data Out of Specification and Cpk
How can Cpk be good with data outside the specification? Here is an example where Cpk is good, yet the process is not centered and data is outside of at least one of the specifications. From PQ Systems.
Human Process Capability - Defects and Errors
Can the capability of a human process ever approach Six Sigma, or is the entitlement of human processes much below what your customers will expect? Find out how many defects and errors you can expect from your human processes. From Zack Swinney and iSixSigma.
One Specification Capability Index
How to calculate capability indices with one specification. From PQ Systems.
Process Capability
Capability versus batch performance, assumptions and an overview of the various indices used. From Skymark.
Process Capability (Cp, Cpk) and Process Performance (Pp, Ppk) - What is the Difference?
Six Sigma process performance is reported in terms of Sigma. But the statistical measurements of Cp, Cpk, Pp, and Ppk may provide more insight into the process. Learn the definitions, interpretations and calculations for Cp, Cpk, Pp and Ppk. From iSixSigma.
Process Capability-in English
Process capability is a tough concept to understand, so here it is in real world terms. From Quality Digest, written by Thomas Pyzdek.
Process Control and Cpk
Should you calculate Cpk when your process is not in control? From PQ Systems.
Sigma To Cpk Conversion Table
A simple table that allows the user to compare Cpk values to process sigma values. From iSixSigma.
Six Sigma Quality Versus Six Sigma Capability
An interesting article on the difference between "six sigma quality" and "six sigma capability." The two phrases are not the same...read why. From PQ Systems.
SPC vs. Knowledge
Ignorance may lead us to a greater understanding of a physical process, but only when it is economical for us to do so. From Quality Digest, written by Thomas Pyzdek.
Statistical Six Sigma Definition
The Six Sigma methodology is well rooted in statistics and statistical mathematics. Learn why six standard deviations is worthwhile for your organization to measure. From iSixSigma.
The Capability Index Dilemma
Should you use Cpk, Ppk, or Cpm? Here's your answer. From PQ Systems.
What Is Cpk?
Actually, where does the "k" come from? The "k" in Cpk is not for Victor Kane, although it would be a fitting tribute to his work in this field. The origins of k actually go back to the 1970s in Japan. The Japanese are credited with developing the the Cp, Cpl, Cpu, Cpk, and k indexes of process capability. From iSixSigma.
Yield The Right Way
Unit yields are typically misunderstood, until now. Here's the full scoop and definitions. From Quality Digest, written by Thomas Pyzdek.
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