Wednesday, 18 March 2015

Guiding your estimates in the right direction

Problem: Estimating effort for (test-)activities is inaccurate

Estimation, or educated guessing is the foundation for many an activity related to management of a project. Given that estimation is not an exact science there will be inaccuracy in the numbers used for planning and resource allocation.

Solution: Apply general estimation rules and use a technique to guide your estimates.

In order to improve accuracy in your estimation you can rely on some general estimation rules and use a technique to guide your estimation.

General estimation rules:

·         A full-time resource will only be productive around 80% of the time.

·         Shared resources, working on multiple projects will have a lower productivity given that they will have to spend time when they do context switching.

·         There is a high degree of optimism in estimates, as most people have tendency of underestimating complexity and time consumption.

·         Base you estimates on multiple sources – Don’t just use own experience, pursue experience of others if possible.

·         Estimation of a task should be done by the person/team responsibility for doing the task.

·         Remember to include issue management, meetings and other supportive activities in the estimate.

·         Break estimates down if possible.

·         Make sure that assumptions, exceptions and limitations are clearly documented as part of the estimate

Techniques for estimating

·         Top-down estimation

·         Bottom-up estimation

·         Combined top-down & Bottom-up estimation

·         Comparative estimation

·         Parameter estimation

·         One-point estimation

·         3-point estimation


The point is that there are numerous techniques that allow you to do more or less scientific estimation – You need to choose the one that fits the purpose and tolerance of your project.

Happy testing!



  1. Informative!! Also agree to the point that there may be different other methods which can be effectively used for the project test estimation techniques. There can’t be a fast rule for estimating the testing effort for a project. It is always recommended to add on to the possible knowledge base of test estimation methods and estimation templates constantly revised based upon new findings.

  2. Test Estimation is to avoid the exceeding timescales and overshooting budgets for testing activities. Based on the project, appropriate test estimation method should be selected and estimates should be calculated.