Tuesday, September 16, 2008

Tool for recording Planning Poker games

When we play Planning Poker I wanted a way of recording the results of each story in a simple way. I also wanted to be able to accept the fact that we won't always reach consensus. So if we have three people playing a 3, person playing a 2 and one person playing a 5, and all of them refuse to change their minds, what do you do? Do you count it as 3? Or 5? Or 2? After you've tried letting the extremes argue (defend) their choices and then had a couple of replays, it starts to feel silly. So being a fan of mathematics and formulas I wanted to be able to live with that difference in opinion and still have a clear way of counting the result. The obvious approach would be to count the average; (2+3+3+3+5)/5 = 3,2 (or rounded to nearest half; 3.0). It works. Do it if you want. I on the other hand wanted the formula to tilt towards "worst case" rather than letting the lower estimates affect it equally. So I used a formula I picked up in (I think) "Agile Estmiating and Planning" by Mike Cohn; Estimate = (1*Min + 2*Avg + 3*Max)/6. The result in the example above would be: (1*2+2*3.2+3*5)/6=3.9. Or rounded to nearest half (which we always do); 4.0.

So for every play we do we record the final estimates from each player. We enter them in the formula above and that is what we the put as the estimate or story point value.

I have a tool I made in Excel, which we now use. Feel free to download and use if you like: