A service level expectation (SLE) forecasts how long it should take a given item to flow from start to finish within the Scrum Team’s Workflow. The Scrum Team uses its SLE to find active flow issues and to inspect and adapt in cases of falling below those expectations.
The SLE itself has two parts: a range of elapsed days and a probability associated with that period (e.g., 85% of work items should be finished in eight days or less). The SLE should be based on the Scrum Team’s historical Cycle Time, and once calculated, the Scrum Team should make it transparent. If no historical Cycle Time data exists, the Scrum Team should make its best guess and then inspect and adapt once there is enough historical data to do a proper SLE calculation.
A reasonable SLE should be less than your Sprint length and shorter improves predictability.
