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Planning poker, also called Scrum poker, is a consensus-based, gamified technique for estimating, mostly used to estimate effort or relative size of development goals in software development. In planning poker, members of the group make estimates by playing numbered cards face-down to the table, instead of speaking them aloud. The cards are revealed, and the estimates are then discussed. By hiding the figures in this way, the group can avoid the cognitive bias of anchoring, where the first number spoken aloud sets a precedent for subsequent estimates.
Contents
Planning poker is a variation of the Wideband Delphi method. It is most commonly used in agile software development, in particular in Scrum and Extreme Programming.
The method was first defined and named by James Grenning in 2002 and later popularized by Mike Cohn in the book Agile Estimating and Planning, whose company trade marked the term and a digital online tool.
The reason
The reason to use planning poker is to avoid the influence of the other participants. If a number is spoken, it can sound like a suggestion and influence the other participants' sizing. Planning poker should force people to think independently and propose their numbers simultaneously. This is accomplished by requiring that all participants show their card at the same time.
Equipment
Planning poker is based on a list of features to be delivered, several copies of a deck of cards and optionally, an egg timer that can be used to limit time spent in discussion of each item.
The feature list, often a list of user stories, describes some software that needs to be developed.
The cards in the deck have numbers on them. A typical deck has cards showing the Fibonacci sequence including a zero: 0, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89; other decks use similar progressions.
The reason for using the Fibonacci sequence is to reflect the inherent uncertainty in estimating larger items.
Several commercially available decks use the sequence: 0, ½, 1, 2, 3, 5, 8, 13, 20, 40, 100, and optionally a ? (unsure), an infinity symbol (this task cannot be completed) and a coffee cup (I need a break). Some organizations use standard playing cards of Ace, 2, 3, 5, 8 and king. Where king means: "this item is too big or too complicated to estimate". "Throwing a king" ends discussion of the item for the current sprint.
Smartphones allow developers to use mobile apps instead of physical card decks. When teams are not in the same geographical locations, collaborative software can be used as replacement for physical cards.
Procedure
At the estimation meeting, each estimator is given one deck of the cards. All decks have identical sets of cards in them.
The meeting proceeds as follows:
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.
Benefits
A study by Moløkken-Østvold and Haugen found that [the] set of control tasks in the same project, estimated by individual experts, achieved similar estimation accuracy as the planning poker tasks. However, for both planning poker and the control group, measures of the median estimation bias indicated that both groups had unbiased estimates, as the typical estimated task was perfectly on target.
In other words, planning poker can be as good as expert estimation - thereby avoiding the Dunning-Kruger effect.
Popularisation
The method was first defined and named by James Grenning in 2002 and later popularized by Mike Cohn in the book Agile Estimating and Planning,
In 2014, Cohn helped create a digital tool for teams to use during estimation meetings and enable geographically dispersed teams to use the planning technique. Features include the ability for teams to play on mobile or desktop devices and use multiple pointing scales, including Fibonacci, modified Fibonacci, and T-shirt sizes.