Tuesday, April 19, 2005

2. The Basis of Estimate

Learn to communicate about the basis of estimates. At the BEGINNING of Inception, if we were to give an estimate it would be based on some sketchy business case and risk list (if we are following RUP). What is the basis of estimate at this point? History. Gut. The SWAG (Scientific Wild A** Guess). Please don't get upset at the language, it is a shop term. Regardless the basis is not on anything specific to this project overall.

At the END of inception, we should now know the number of use cases, number of use case outline flows, number of use case outline steps, number of features, number of mechanisms, number of mechanism operations and more project specific measures. So now it is time to re-estimate, but notice we have a NEW BASIS OF ESTIMATE. Inception stuff. It is tough to argue with us at this point. The first estimate was a guess based on history. This one is a better guess based on tangible stuff. You can check our math if you like.

At the end of elaboration our basis of estimate changes AGAIN! Now it is based on ACTUAL PERFORMANC MEASURES. Since we have built a growing product during Elaboration (confused? Take the test on my blog!) we know the ACTUAL capability of THIS SPECIFIC TEAM on THIS SPECIFIC PROJECT. That is pretty hard to refute. Again we re-estimate and invite them to check our math. When the client sees the basis of estimate changing each time they will understand why we are doing this. And we do it every time, so they begin to get used to the rhythm of it. History, Inception Measures, Elaboration Actuals. Got it. Makes sense.

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