Archive for February 17, 2010

Ever committed to an estimate?

I’ll try a real short blog post today. In his book ‘Agile Estimating and Planning’, Mike Cohn has a short but powerful paragraph called ‘Estimates Become Commitments’. He sees this as one of the major issues with traditional planning.

There is a clear difference: An estimate has a PROBABILITY (usually less than 100%).  In order to be able to commit, further analysis such as looking at uncertainties (risks), other environmental and business factors needs to be undertaken. A commitment is then made to an exact date / value, based on a level of confidence deemed sufficient in that case.

This is an issue that exists in ‘traditional’ project environments, but will probably also be found in more agile organizations (careful with the ‘projected’ lines in the sprint burndown charts!). Obviously, organizational culture is a major influence here.

There are a few simple things you can do to clearly distinguish estimates (significantly less than 100% probability) from commitments:

Use ranges: Rather than giving a fixed date (‘We’ll release June 10th’), provide a range (‘The release will be ready between beginning of June and mid of July’). You could also attach levels of probability to the range you give, plus a ‘most likely’ value somewhere in the middle.

Remember your math lessons at school: Level of precision of your numbers indicates a certain level of confidence! If you say ‘365 days’ you imply a higher level of confidence than if you say ‘1 year’. If someone tells me a task will take 3.25 hours, I certainly take this for granted.

So be careful with how you word your plans / predictions, and if you’re at the receiving end, rather check back ‘Is this your commitment or an estimate?’.

February 17, 2010 at 20:16 Leave a comment


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