Pareto, Scatter and Cause-Effect Diagrams

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Question of the month: What is the difference between common cause and assignable cause?

Email articles in September discussed applying statistical process control (SPC) methods to business processes. Today many organizations have implemented a rigorous application of statistical methods called Six Sigma. However, Six Sigma is not for everyone because it requires extensive, specialized training in statistical methodology, and a thorough understanding of the processes involved. Still, much of the value of Six Sigma can be achieved with a few simple statistical tools.

We also launched the Spanish Language Employee Handbook in September.

Road to Six Sigma: Pareto Diagrams

The Pareto Diagram is based on the empirical observation that a large majority of the results of a system are attributable to a few actors within the system. Often called the 80-20 rule, the Pareto’s Principle is a way of separating the “vital few from the trivial many”.

Read more about SPC and pareto diagrams;

Road to Six Sigma: Cause-Effect and Scatter Diagrams

Often referred to as fishbone diagrams, cause-effect diagrams were invented in Japan in 1943 by Kaoru Ishikawa as an aid to explaining how various factors in a complex process can be sorted out and related. Scatter diagrams are a special type of cause-effect diagram developed from historical or experimental data and reveal the relationship, if any, between variations in one variable and variations in another.

Read more about cause-effect and scatter diagrams;

Employee Handbook in Spanish

In response to a growing demand, for an employee handbook in Spanish, we launched the Spanish language version of the popular Bizmanualz Employee Handbook in September. This professional translation is meant to be used by Spanish-speaking employees in offices of any size. It contains over 100 pages of policies, tips and information easily editable in MS Word.

Read more about the Employee Handbook in Spanish;

Statistical Process Control (SPC) has been used in the manufacturing world for decades. In the 1920’s Walter A. Shewhart of Western Electric introduced the concepts of Assignable Cause and Chance Cause affecting the variability of a process or its output. Shewhart went on to introduce the control chart and his methodologies were later adopted by W. Edwards Deming.

We will continue this series on SPC in October.

On That Note

Answer to this month’s question:

Common cause is associated with the “natural” variation of the system and is present in all systems and processes. It is possible to reduce, but not eliminate, common cause by redesigning the system. On the other hand, it is possible to find and eliminate assignable cause variability from the system. Presence of assignable cause in the system makes the output unstable and unpredictable. Presence of common cause only, however, will still enable the system to produce stable and predictable output.

Please feel free to contact us with any questions or comments that you may have about our products, services or articles. Also, please let us know if you’d like any specific topic addressed in our future articles.

Regards,
Chris
Bizmanualz, Inc.