Software Quality Metrics

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Metrics /Measure


The degree to which the software performs the required functions accurately

Defects / KLOC or
Defects / Function points


Maintainability is the ease with which a program can be correct if an error occurs.

MTTC (Mean time to change) -- Once error is found, how much time it takes to fix it in production.


This measure the system’s ability to with stand attacks to its security

Integrity = Summation [(1 - threat) X (1 - security)]


How usable is your Software program

   * -Skill required to learn the system
    * -Time required to be productive on new system
    * -Net increase in productivity by use of the new system.
    * User questionnaire survey results

Defect Removal Efficiency

Defect Removal Efficiency (DRE) is a measure of the efficacy of your SQA activities..Ideal value of DRE should be 1 which means no defects found.

DRE = E / ( E + D )

Where E = No. of Errors found before delivery of the software and D = No. of Errors found after delivery of the software.

Test Coverage


Number of units (KLOC/FP) tested / total size of the system

Quality of Testing =

No. of defects found during Testing/(No. of defects found during testing + No of acceptance defects found after delivery) *100

Customer satisfaction index

Number of system enhancement/Maintainence requests per year
Call volume to customer service hotline



Availability (percentage of time a system is available, versus the time the system is needed to be available)
- Mean time between failure (MTBF)
- Mean time to repair (MTTR)
- Reliability ratio (MTBF / MTTR)
- Number of product recalls or fix releases
- Number of production re-runs as a ratio of production runs