Testing Tips _Day 3

Methods for Test Estimation

1. Best Guess: This technique is purely guesswork and based on the some sort of experience. The method is very common, but since it is based on your gut feeling, its uncertainty contingency is probably around 200% or even higher.

2. Ad-hoc Method: The test efforts are based on tentative timeframe. The timeline set by managerial or marketing personnel or by client without any guess/experience. Alternatively, it is done until the budgeted finances run out.
This is very common practice in extremely immature organizations and has error margins of over 100% at times.

3. Experience Based: Analogies and experts:

• Metrics collected from previous tests.
• You already tested similar application in previous project.
• Inputs are taken from Subject Matter experts who know the application (as well as testing) very well.

4. Work Breakdown Structure: It is created by breaking down the test project into small pieces. Modules are divided into sub-modules. Sub modules are further divided into functionalities and functionalities are divided in sub-functionalities.
Review all the requirements from Requirement Document to make sure they are added in WBS. Now you figure out the number of tasks your team needs to complete. Estimate the duration of each task.

5. Delphi Technique – Same as above WBS. Here functionalities and each task are allocated to each team member. Then team member gives estimate that they will take this many hours to complete the task.

Averagely, this technique gives good confidence in the estimation. This technique can be combined with other techniques.

6. Three-point Estimation – This technique is based on statistical methods In this technique, task is broken down into subtasks (similar to WBS) and then three types on estimation are done on each chunk –

• Optimistic Estimate (Best case scenario in which nothing goes wrong and all conditions are optimal.) = a
• Most Likely Estimate (most likely duration and there may be some problem but most of the things will go right.) = m
• Pessimistic Estimate (worst case scenario which everything goes wrong.) = b
 

Formula to find Value for Estimate (E) = a + (4*m) + b / 6

Standard Deviation (SD) = = (b - a)/6