What is Defect Density?

DEFINITION
Defect Density is the number of confirmed defects detected in software/component during a defined period of development/operation divided by the size of the software/component.

ELABORATION
The ‘defects’ are:

• confirmed and agreed upon (not just reported).
• Dropped defects are not counted.

The period might be for one of the following:

• for a duration (say, the first month, the quarter, or the year).
• for each phase of the software life cycle.
• for the whole of the software life cycle.

The size is measured in one of the following:

• Function Points (FP)
• Source Lines of Code

DEFECT DENSITY FORMULA

USES

• For comparing the relative number of defects in various software components so that high-risk components can be identified and resources focused towards them.
• For comparing software/products so that quality of each software/product can be quantified and resources focused towards those with low quality.