Planning Poker is a fast, card based approach to team estimation. User stories are presented to the team and discussed as a group to round out understanding. In Scrum, this can be played in the Sprint Planning Meeting.
- In the planning session each participant (player) gets a set of cards with the values 0, 0.5, 1, 2, 3, 5, 8, 13, 20, 40, 100, infinity and ?.
- One story is estimated at a time.
- Each story is discussed briefly.
- At the end of the discussion each player selects a card but doesn’t reveal his choice yet.
- The cards are all revealed at the same time.
- People with high estimates and low estimates are given a soap box to offer their justification for their estimate and then discussion continues. Often it is these discussions that reveal more aspects to be considered.
- Repeat the estimation process until a consensus is reached.
- If the average is greater than 20 points then the story should be split up and its parts estimated.
All people who would work on delivery are involved in estimation.
The cards are numbered as they are to account for the fact that the longer an estimate is, the more uncertainty it contains. Thus, if a developer wants to play a 6 he is forced to reconsider and either work through that some of the perceived uncertainty does not exist and play a 5, or accept a conservative estimate accounting for the uncertainty and play an 8.
Avoid Anchoring where a stated opinion about the amount of time involved in a task can skew the rest of the team’s estimates.
It is important to remember the fidelity of most estimation input data is poor, i.e. we are usually dealing with approximations and best-guesses for work effort. Software development is difficult to predict and we get diminishing returns beyond a certain point of investing more effort in the estimation process.
There’s a good description of a Planning Poker session by Crisp.
There are free templates for the cards, for example, first page, second page.
The cards can be purchased from various sources but the cheapest are the originals from Mountain Goat Software, Mike Cohn’s company.
For distributed teams there’s a Planning Poker web-based application.