Remove Defects in Production

How many times it is costlier to remove defects in production than removing them before coding?
a) 10 times
b) 50 times
c) 100 times
d) 200 times

Questions by mathan_vel   answers by mathan_vel

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The answer is c) 100.

This reflects what is called the 1-10-100 Rule based on a study commissioned by AT&T in the 1970s.  It explains how a failure to prevent a defect at its source escalates the cost in terms of real dollars. There are many costs once a defect is released to the public: 1) customer disatisfaction and corresponding negative word of mouth, 2) loss of customer loyalty, and 3) the cost to correct the defect in the field.  The principle is not unlike the traditional medical axiom: “An ounce of prevention is worth a pound of cure.”

Again, in terms of a software development cycle, the relationship between these costs is reflected in the 1-10-100 Rule.  If a defect is corrected during development, the cost is a factor of 1 ( X * 1, whatever X may be ).  If the defect is discovered and corrected through QA and/or Testing, then the cost becomes a factor of 10 ( X * 10 ).  However, if the defect slips by QA and is released to production, then the costs becomes much greater, a factor of 100 ( X * 100).


  • Nov 30th, 2009

It depends on the bug type.
Like Sev1 means most of the business is loss because of this bug.
Fixing time may be less but damage is huge. So we cannot estimate the cost per bug in Production. It depends on time to time.

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