Scrum poker, also known as Agile or "planning poker" is a gamified way of estimating effort, be it for software development or any other Agile project.
When planning a sprint, accurate estimates tend to be rather important for on-time delivery. It normally takes several sprint iterations to get it right, especially for new teams.
Once a feature has been discussed by the team, each team member writes down a number in terms of effort. Fibonacci numbers are a great way to do this, as each number highlights the difference in effort. Normally there isn't much difference between a level 7 or 8 effort, or even a level 6 and 8 effort, however, with Fibonacci Numbers, the gaps tend to display small, medium, high and very high levels of effort.
Fibonacci number designated levels of effort: 3, 5, 8, 13, 21, 34, 55 etc.
Once everyone has written down their numbers, it is time to reveal them. Those with the highest and lowest number need to explain their reasoning. Oftentimes someone may know a shortcut (reason for the low estimate) or has thought of extra complications (reason for the high estimate).
Note that this only works for teams where democratic decision making is the norm and the management or ownership offers a safe space to speak up. This will not work with autocratic teams, where the manager or business owner does routinely overrides the team's intelligence or even humiliates those who speak up.
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