According to the SAFe Agile Product Management APM (6.0) documents and learning resources, Weighted Shortest Job First (WSJF) is a prioritization model used to sequence work for maximum economic benefit. It is calculated by dividing the cost of delay by the job duration or size. To estimate the cost of delay, three factors are considered: user and business value, time criticality, and risk reduction or opportunity enablement. To estimate the job duration or size, a relative scale such as Fibonacci is used. The highest value in the Fibonacci scale is set as the "ceiling" and the lowest value is set as the "floor". The items are then scored by comparing them to the ceiling and the floor, and assigning them the closest Fibonacci number. The WSJF score is then obtained by dividing the cost of delay score by the job duration or size score. The items with the highest WSJF score are prioritized first.
References:
* WSJF - Scaled Agile Framework
* Weighted Shortest Job First (WSJF) | Definition and Overview - ProductPlan
* Weighted Shortest Job First - Open Practice Library