Tuesday 31 May 2011

Story points = time - but time is relative

I'm reading the book Agile Estimating and Planning by Mike Cohn. I "disagreed" with some things he wrote in the book so I wrote him a mail asking him mainly about the story points. My opinion was that you should never compare story points with work-load. He gave me a good answer and also a link to his blog (I'm not going into details of the answer) http://blog.mountaingoatsoftware.com/its-effort-not-complexity.

Now I understand I had got it all wrong. It's absolutely valid to compare it with work load. It's just that my time is different than your time. That's why you shouldn't use time when e.g. playing planning poker - because five points for me may be ten hours of work, but for someone else it's five hours or maybe twenty. But you should never tell the others what a "five" is for you. Just agree on that ten points are twice as much work and two points are half (not quite). Thus it's a good method to try to find a basic story that everyone can agree on is in the middle range and then compare all other stories to that one.

Then - if the team is pretty much the same and the project is similar - you could actually say that 100 story points = 400 hours of work (or something like that).

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