Root cause

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A root cause is a cause that is at a root of an effect. An effect can have more than one root. Thus a given effect can have, and usually does have, more than one root cause.

In continuous process improvement (CPI), a root cause is the most basic reason for a defect or problem in a product or process. Elimination of the root cause leads to the elimination of the defect or problem.

Another definition for "root cause" that was created by Mark Paradies and David Bush starting in 1985 is:

ROOT CAUSE - The most BASIC cause (or causes) that can REASONABLY be identified that management has control to FIX and, when fixed, will prevent (or significantly reduce the likelihood of) the problem's recurrence.

In the definition above, "management's control to fix" does not include managements' willingness to fix the root cause or budget constraints. This term simply eliminates natural laws (like gravity as the "root cause" of a fall) from being used as root causes. It also means that some problems (like a drunk driver crossing the center line and striking a company car) may be beyond managements' control to fix (no root cause within management's grasp).

Other ideas ...

In order to be a root cause an item needs only two attributes: 1) it is a cause 2) it is at a root. Root causes do not have to be correctable. They do not have to be under any one's control. They happen to have the attribute that if they are favorably modified the effect will also be favorably modified.

Tools such as the 5 Whys or the Fishbone or Ishikawa diagram are used to identify the root cause of a problem or defect as part of a CPI project aimed at improving product or process quality.

In using the Five Whys, the analyst should bear in mind that understanding the causation of an effect involves understanding the necessary and sufficient influences that resulted in the nature and magnitude of the effect.

In using the Ishikawa Fishbone Diagram the analyst should bear in mind that there are many versions of the Fishbone Diagram and that most are more properly classified as brainstorming tools, rather than root cause analysis tools.

Other more advanced root cause analysis tools have been created since the development of fishbone diagrams and 5-Whys.

External links

What is Root Cause Analysis?
Meaning of Root Cause, Part I
Meaning of Root Cause, Part II
Root Cause at Six Sigma
Apollo Methodology Root Casue Analysis
RealityCharting™ Root Cause Analysis - Apollo's Root Cause Analysis Software
Root Cause Interactive Online Tutorial & Training
Implement A Cost Effective Root Cause Analysis Process in your Plant