Monday, September 28, 2009

Introduction to Planning Poker

Many of the techniques of Agile development combine together to provide more than the sum of their parts. One technique that definitely fits this description is the Planning Poker method for doing estimation. In part 1 of this post, I will quickly describe the mechanics of Planning Poker. I will then go on to describe how user stories, whole teams, story point estimation, and velocity all work to multiply the value of Planning Poker and how Planning Poker also reinforces the use of and value of the other practices. If you are already familiar with Planning Poker, you may want to skip ahead to "The Five Essential Ingredients of Great Agile Estimation".

Planning Poker is an estimation technique first described by James Grenning in 2002 in a paper by the same name [pdf]. When I first heard about Planning Poker, I couldn’t help but chuckle. It seemed a bit silly to mix software development and poker. After reading Mike Cohn’s excellent book “Agile Estimating and Planning” I had a good grasp of the mechanics of Planning Poker, but it felt like just a variant of the Delphi method and thus nothing new.

About a year ago we had Kenny Rubin come in to do some Scrum training for us. That was just the shot in the arm that we needed to supercharge Agile adoption at AccuRev. If you are looking for an Agile trainer, I highly recommend Kenny Rubin. It was based on Kenny’s explanation and recommendation that we decided to try Planning Poker on a real project. The results were terrific and after a single session we were hooked. Planning Poker is now a standard part of our Agile process.

The Basics
In order to play Planning Poker, each participant will need a deck of Planning Poker cards. These are easy to obtain, just Google for “Planning Poker cards” or make your own. You will need the following cards: ½, 1, 2, 3, 5, 8, 13, 20 and a card that indicates “I’ve had enough.” The numbers on the cards represent estimates. You can use story points, ideal days, or some other measure, but in this point I am assuming (and advocating) story points. Typical decks contain cards for much larger numbers than 20, but I think you’ll find that 20 and higher are rarely used once you’ve been using Planning Poker for a year or two.

The whole team gets together for a set amount of time to do story estimation. An hour is usually a good amount of time, but this is completely up to you. When I say “the whole team” I am assuming that you are using small cross-functional teams of 5-9 people (see later parts that discuss the use of whole teams).

Estimation is done on a story-by-story basis in the same order as the backlog, starting with the first story that needs estimating. Somebody reads and describes the story. This is often the product owner, but could be anybody. Some teams do story point estimation without the product owner and just skip stories which they are unable to do without the product owner’s involvement. After the story has been read, participants discuss the story for a bit and then decide on an estimate by picking one of their cards and laying it face down in front of themselves. Once everybody is ready, all of the estimates are shown. If the estimates are all the same, you are done.

Usually, some of the estimates are particularly low or particularly high. A low estimate can indicate that the estimator left something out, or possibly that they know a way to reuse existing work or have some other good information that other folks weren’t aware of. A high estimate may indicate many things, but most commonly it means that the estimator is thinking of something that other folks may not be aware of. For instance, somebody may point out that there is no test framework or tooling for a particular technology and that to adequately test the story the team will need to do a lot of setup work.

In any case, after a round of discussion, everybody chooses a new estimate. This is repeated until the team comes to consensus on the estimate. The estimate is given to the story and then you move on to the next story. You end when you hit the end of the meeting time, you run out of stories to estimate, or somebody plays the “I’ve had enough” card.

The Benefits
One of the biggest benefits of Planning Poker is the sense of team that it creates. The whole team is participating in the estimation. This creates a greater sense of team ownership and team responsibility for each story. Another major benefit of Planning Poker is that you leverage the collective wisdom of the whole team. However, this really only works well when you are using whole teams in the Agile sense of the term.



Next: The Five Essential Ingredients of Great Agile Estimation

6 comments:

James Grenning said...

Hi Damon

I'm glad you're playing planning poker. You might be interested in the Planning Poker Party a technique for estimating a large batch of stories. Also here's my $0.02 on story points vs. ideal days.

Damon Poole said...

James,

Whoa! I feel like I just fell down the rabbit hole. I had no idea there was so much material on Planning Poker and variants. Once I've recovered my wits I will venture in a bit more slowly to learn more!

High-Low Story Showdown? Whoda thunk?!

Cheers,

Damon

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