5.2.6 Test Estimation Techniques

There are a number of estimation techniques used to determine the effort required for adequate testing. Two of the most commonly used techniques are:

• The metrics-based technique: estimating the test effort based on metrics of former similar projects, or based on typical values

• The expert-based technique: estimating the test effort based on the experience of the owners of the testing tasks or by experts

For example, in Agile development, burndown charts are examples of the metrics-based approach as effort remaining is being captured and reported, and is then used to feed into the team’s velocity to determine the amount of work the team can do in the next iteration; whereas planning poker is an example of the expert-based approach, as team members are estimating the effort to deliver a feature based on their experience (ISTQB-CTFL-AT).

Within sequential projects, defect removal models are examples of the metrics-based approach, where volumes of defects and time to remove them are captured and reported, which then provides a basis for estimating future projects of a similar nature; whereas the Wideband Delphi estimation technique is an example of the expert-based approach in which a group of experts provides estimates based on their experience (ISTQB-CTAL-TM).