Weighted Shortest Job First

Weighted Shortest Job First or ‘WSJF’ is a measurement to facilitate objective decision-making. It helps Product Owners, Product Managers and Portfolio Management to prioritize the work which delivers the highest value in the shortest amount of time. This method was first mentioned in Donald G. Reinertsen’s Principles of Product Development Flow book.

In agile way of working one of the most important principles is to “take an economic view”. This means that, in order for us to take decisions that will help to improve value and quality delivery in the shortest sustainable lead time, we need to have a better understanding of the economics supporting our system and that our choices are made from this economic context.

If we want to be able to take objective and fact-based decisions, we need to rely on quantitative data. In addition, we should not only look at the value expected but also at other components such as time criticality, risk reduction, opportunity enablement and the size of the job. Having a clearer understanding of the different elements involved, and reviewing these from an economic context, allows for more reliable and sustainable decision making. Having a shared framework for prioritization also allows for decentralized decision-making. Lengthy queues are the biggest cause for delays. Managing queues and optimizing the flow of work is crucial to reduce delays and increase value delivery and revenues. The key to manage those queues is to measure the value delivered, Cost of Delay, against the cost in terms of effort.

WSJF used correctly  will help to prioritize the most valuable work in the shortest sustainable lead time and thus to queue work in the most optimal way.

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User/Business value:

  • Relative value to customers or business
  • What is the added value to our (end-)users?
  • How does the solution impact user satisfaction?
  • What is the expected revenue?

Time criticality:

  • Relative urgency
  • Is there a fixed deadline?
  • How does value change over time?
  • Will our (end-) users wait for us or move to competition?

Risk reduction and Opportunity enablement:

  • Relative value to customers or business
  • What is the added value to our (end-)users?
  • How does the solution impact user satisfaction?
  • What is the expected revenue?

To determine the values of these elements we use the values of the modified Fibonacci scale: 1, 2, 3, 5, 8, 13, 20, 40, 100. The reason for using these values is that they allow relative estimation. Especially early on in the process we have little information on the work to be done to exactly determine the absolute values. Not to mention that this would require a lot of analysis and therefore time. What we do know early upfront is how we can compare different types of work to each other in terms of impact on User Value or Business Value. We don’t know the exact impact on user value, but comparing epic A with epic B, we can for example agree that epic B will impact user value by three times more than epic A.

References

  • Reinertsen, D. (2009). The principles of product development flow. Redondo Beach,Calif.: Celeritas Publishing.
  • Scaledagileframework.com. (2019). WSJF – Scaled Agile Framework. [online] Available at: https://www.scaledagileframework.com/wsjf/ [Accessed 10 Oct. 2018].