Software Metrics

Software Metrics

Here are few software metrics which could be useful to you.

We can classify them into

a) Process metrics

Metrics pertaining to the process quality. It includes

  • defect distribution
  • testing effort distribution
  • testing and review efficiency
  • test planning

b) Product metrics

Metrics pertaining to the product quality. It  includes

  • Defect Density
  • Testability (robustness of the product)
  • Residual defect density

I have tried to illustrate a few of them.

1.    Schedule Variance   : Any difference between the scheduled completion of an activity and the actual completion is known as Schedule Variance.

Schedule variance = ((Actual calendar days – Planned calendar days) + Start variance)/ Planned calendar days x 100

2.    Effort Variance : Difference between the planned outlined effort and the effort required to actually undertake the task is called Effort variance.

Effort variance = (Actual Effort – Planned Effort)/ Planned Effort x 100

3.    Size variance : Difference between the estimated size of the project and the actual size of the project (normally in KLOC or FP)

Size variance = (Actual size – Estimated size)/ Estimated size x 100

4.    Requirement Stability Index : Provides visibility and understanding into the magnitude and impact of requirements changes.

RSI = 1- ((No of changed + No of deleted + No of added) / Total no of Initial requirements) x100

5.    Productivity (Project) : It is a measure of output from a related process for an unit of input.

Project Productivity = Actual Project Size / Actual Effort spent for the project

6.    Productivity ( for test case preparation)

Productivity in test case preparation = Actual no of test cases/ Actual effort spend on test case preparation

7.    Productivity (for test case execution)

Productivity in test case execution = actual no of test cases / actual effort spend on testing

8.    Productivity (defect detection)

Productivity in defect detection = Actual no of defects (review + testing) / actual effort spend on (review + testing)

9.    Productivity (defect fixation)

Productivity in defect fixation = actual no of defects fixed/ actual effort spend on defect fixation

10.    Schedule variance for a phase   : The deviation between planned and Actual schedule for the phases within a project.

Schedule variance for a phase = (Actual Calendar days for a phase – Planned calendar days for a phase + Start variance for a phase)/ (Planned calendar days for a phase) x 100

11.    Effort variance for a phase   : The deviation between planned and actual effort for various phases within the project.

Effort variance for a phase = (Actual effort for a phase – planned effort for a phase)/ (planned effort for a phase) x 100

12.    Cost of Quality   : It is a measure in terms of money for the quality performance within an organization

Cost of quality = (review + testing + verification review + verification testing + QA + Configuration management + measurement + training + rework review + rework testing)/ total effort x 100

13.    Cost of poor quality : It is given as the cost of implementing imperfect processes and products.

Cost of poor quality = rework effort/ total effort x 100

14.    Defect density   : It is given as the number of defects detected in the software during the development divided by the size of the software (typically in KLOC or FP)

Defect density for a project = Total number of defects/ project size in KLOC or FP

15.    Review Efficiency   : defined as the efficiency in harnessing/ detecting review defects in the verification stage.

Review efficiency = (number of defects caught in review)/ total number of defects caught) x 100

16.    Testing Efficiency

Testing efficiency = 1 – ((defects found in acceptance)/ total no of testing defects) x 100

17.    Defect removal efficiency   : Gives the efficiency with which defects were detected and minimum defects were filtered down to the customer.

Defect removal efficiency = (1 – (total defects caught by customer/ total no of defects)) x 100

18.  Residual Defect Density

Residual Defect Density = (total number of defects found by customer)/(Total number of defects including customer found defects) x 100


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