Defect Removal Efficiency

What is this formula?

Defect Removal Efficiency measures the proportion of total known defects that were detected and removed before software release.

It is a key software quality metric because it evaluates how effective testing, inspections, code reviews, and quality assurance activities were before the product reached users.

A higher DRE indicates that fewer defects escaped into production.

When to use it

Use this formula when:

- evaluating software testing effectiveness,

- measuring quality assurance performance,

- comparing releases,

- analyzing defect escape trends,

- improving software development processes.

Example

A software team removes:

Dr = 180 defects before release

After release, users report:

Dp = 20 defects

Formula:

DRE = Dr / (Dr + Dp)

Substitution:

DRE = 180 / (180 + 20)

DRE = 180 / 200

DRE = 0.90

Result:

Defect Removal Efficiency = 0.90 or 90%

Applications

- Software quality assurance

- Testing process evaluation

- Release readiness analysis

- Defect prevention programs

- Continuous improvement

- Software reliability engineering

Note

Defect Removal Efficiency is an empirical quality metric. It depends on how defects are classified, when they are counted, and how completely post-release defects are reported. It does not measure defect severity directly, so two projects with the same DRE may still have different business or safety impacts.