The numbers used to vote when planning are 0, 0.5, 1, 2, 3, 5, 8, 13, 20, 40, 100. Is there a meaning when those numbers are chosen? Why don't we just choose 1,2,3,4.. for the sake of simpliness?
+10
A:
The point is that as the estimates get bigger, they become less likely to be accurate anyway. There's no point in debating the merits of 34 vs 35 - at that point you're likely to be miles out anyway. This way just makes it easier: does this feel more like a 20-point task or a 40-point task? Not having the numbers between 21 and 39 forces you to make look at it in this "bigger" way. It should also be a hint that you should break the task down further before you come close to doing it.
Jon Skeet
2010-07-11 07:24:38
@Downvoter: Care to comment?
Jon Skeet
2010-07-16 19:46:36
Good summary. I'll also say that you may find you want to limit the upper end of the scale. Some teams will do something like: 1, 2, 3, 5, 8, 13, + -- Where "+" means "too big". That's an indication the story should be split into smaller bits, which usually reduces risk.
James Cooper
2010-07-20 20:25:49
@James Cooper: Even better is to do something like 1, 2, 3, + -- where "+" means "too big". And then you don't have to worry about Fibonacci. ;-)
Don Roby
2010-08-20 01:13:55
+3
A:
I've never seen that sequence used, the Fibonacci series (1 2 3 5 8 13 21 34) is more common. The idea is to avoid tricking yourself into thinking there is precision when there isn't.
David Dorward
2010-07-11 07:25:06
Will Vousden
2010-07-11 07:40:53
It's fibonacci to a point, with some roudning at higher numbers. I've seen it on a few sets of printed scrum cards before. Having a zero is useful, but 0.5 seems daft to me.
Dan Puzey
2010-07-11 07:54:38
@Dan No, it isn't. With time, you might find a smaller story than the smallest stories of the first sprints. This is where 0.5 comes in.
Pascal Thivent
2010-07-11 23:19:26
+3
A:
All the details are explained here: http://en.wikipedia.org/wiki/Planning_poker
The sequence you give has been introduced by Mike Cohn in his book "Agile Estimating & Planning" (therefore the sequence is copyrighted, you need to obtain the permission to use it or you can also buy decks from his online shop).
The original planning poker sequence is a bit different and described he by his original inventor (James Grenning) : http://renaissancesoftware.net/papers/14-papers/44-planing-poker.html
Pierre 303
2010-07-11 09:44:02