Test-Case Defect Yield
This metric tracks the number of defects found as a result of the testing effort.
Main Description

Purpose

This metric helps determine the effectiveness of test cases in identifying defects. In addition to determining effectiveness, you can also use it to reduce testing costs by reducing the number of times that a test is run.

Definition

Count these instances:

  • Total number of defects found per test case
  • Number of times the test case has been run

Then calculate the average defect yield per test case run (total number of defects found by a test case / number of times that the test case has been run).

Analysis

If you run the test frequently, it is a candidate for automation. If you run it frequently, but it never detects any defects, it is a candidate for retirement. If it rarely results in defects, it is a candidate for refactoring into a different test case.

Note:
This requires traceability to be established between defects and test cases.

Frequency and reporting

Review Test Case Defect Yield at the end of each iteration during the team's iteration assessment.

Collection and reporting tools

Data for this metric can be collected with  IBM® Rational® Quality Manager®.