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

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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!

/Nicolai

2 comments:

  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.

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  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.

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