Planning Poker References
Planning poker works because it lets the people who are actually going to be completing the work do the estimating.
After reviewing the literature on estimating, Magne Jørgensen concluded that “the people most competent in solving the task should estimate it.” They have the expertise and hands-on experience to draw from to help them make a more accurate estimate. Planning poker allows all individuals from a cross-functional team to give estimates independent of each other, drawing on their own areas of expertise, thereby increasing the estimate's accuracy.
Estimates derived from planning poker are more accurate because estimators are called upon by their peers to justify their estimates.
After the initial estimates have been entered, participants in planning poker have the opportunity to discuss how they arrived at their estimate. Knowing one has to justify an estimate has been shown to result in a more accurate estimate. For more information, see Hagafors and Bremmer, “Does Having to Justify One's Decisions Change the Nature of the Decision Process?”
The lively group discussion common in planning poker also helps lead to better estimates.
In another study Jørgensen and Moløkken found that lively discussions, which are typical of a planning poker session, result in more accurate estimates, partly because they uncover missing information. This works especially well with planning poker because the sometimes vague language of a user story can be interpreted in many ways.
Planning poker provides a true average of individual estimates, which has been shown to yield better results.
Studies by Hoest and Wohlin show that averaging individual estimates leads to better results. In planning poker, estimates are truly individual, both because each person chooses an estimate from a finite group of numbers and because each person does this with no input or help from others involved in the process. Because all estimates are revealed at the same time, no one is subconsciously influenced by another's estimate. Each round of poker brings these individual numbers closer together until consensus is reached and an average of the estimates is calculated.
Planning poker works because it's fun.
stimating is not usually something most developers enjoy. However, Planning Poker™ adds an element of fun that is missing from other estimating approaches. This helps keep estimators engaged and willing to participate. But, don't just trust us—give it a try.