Planning Poker

Overview

Planning Poker is an estimating technique used by many agile software development teams.

Start with a set of planning poker cards.  Each card has one of the numbers in your chosen range of story points (0, 1, 2, 3, 5, 8, 13, 20, 40, and 100).  Every participant is dealt a "hand" that contains the full range of available story points.

After the cards are distributed, the game begins.

1. The Scrum Master presents the top item in the product backlog to the team.
2. The team discusses what the story is.
3. The product owner clarifies questions, assumptions, and unknowns – as well as acceptance criteria.
4. Each team member privately decides how big this story is relative to a reference story, a series of reference stories, or all of the stories on the product backlog.
5. At the count of three, everyone shows his chosen card simultaneously.

If everyone played the same card, the team can log the estimate and move on to the next story.

If there is a wide variance, then the team spends time discussing the story.  To focus the discussion, have the low bidder and the high bidder both explain their reasoning for their estimates.  The conversation is valuable here, not the number, because that's where the learning occurs and any assumptions are uncovered.  After a brief 30-second to one-minute discussion, the team repeats steps 4 and 5.  This continues until the team agrees on an estimate for the story.

Further Information

Source: http://msdn.microsoft.com/en-us/library/hh765979.aspx