Task planning and estimation is vital to develop products iteratively in accordance with the requirements specified in the Prioritized Product Backlog. The Scrum Team, in Task Estimation Meetings, estimates the effort required to accomplish each task in the Task List. The result of this process is an Effort Estimated Task List. The Scrum Team uses the Task list, a comprehensive list containing all the tasks to which the team has committed for the current Sprint, to develop an Effort Estimated Task List. The Task List must include any testing and integration efforts so the product increment from the Sprint can be successfully integrated into the deliverables from previous Sprints. Even though tasks are often activity based, the level of granularity to which the tasks are decomposed is decided by the Scrum Team.
During Task Estimation Meetings, the Scrum Team uses the Task List to estimate the effort required to complete a task or set of tasks and to estimate the people effort and other resources required to carry out the tasks within a given Sprint. One of the key benefits of this technique is that it enables the team to have a shared perspective of the User Stories and requirements so that they can reliably estimate the effort required. The information developed in the Task Estimation Meetings is included in the Effort Estimated Task List, and it is used to determine the velocity for the Sprint. In this workshop, the Scrum Team may use various techniques such as decomposition, expert judgment, analogous estimation, and parametric estimation. Task Estimation Meetings may also be combined with Task Planning Meetings.
To maintain relative estimation sizes and minimize the need for re-estimation the team uses estimation criteria. Estimation criteria can be expressed in numerous ways, with two common examples being story points and ideal time. For example, an ideal time normally describes the number of hours a Scrum Team member works exclusively on developing the project’s deliverables, without including any time spent on other activities or work that is outside the project. Estimation criteria make it easier for the Scrum Team to estimate effort and enable them to evaluate and address inefficiencies when necessary.
The output of task estimation is the Effort Estimated Task List. It is a list of tasks associated with the User Stories committed to in a Sprint. Typically, the accuracy of estimates varies with team skills. Estimated effort is expressed in terms of the estimation criteria agreed on by the team. This Effort Estimated Task List is used by the Scrum Team during Sprint Planning Meetings to create the Sprint Backlog and Sprint Burndown Chart.
