What is Weighted Shortest Job First?

Weighted Shortest Job First, abbreviated as WSJF, is an ostensibly easy Scaled Agile Framework (SAFe) technique for prioritizing items on a backlog. It seeks to identify the most economically rewarding initiatives that can be completed in the shortest time. It is a scoring approach that involves assigning scores to initiatives and then giving priority to those with the highest readings.

The model focuses on job sequencing as the best means of achieving maximum economic outcomes. It requires continuous updating of priorities in a flow-based system. You update your priorities based on certain factors, including time and relative value.

WSJF isn’t only useful to product teams for prioritizing items on the product backlogs. It can also be used by marketing teams to identify the campaigns that give the best return on investment.

Cost of Delay and Job Duration

Two terms that you’ll often come across when people discuss WSJF are Cost of Delay (CoD) and Job Duration, or Size. These are what drive the overall score that each initiative gets and their order of priority.

Cost of Delay

CoD is what you’d lose (in monetary terms) when you delay a job or fail to complete it within a set period. Take note that “jobs” in SAFe refer to features, capabilities, and epics.

Let’s illustrate a bit with a feature. Assume that its expected value is $200,000 a month. If you were to delay by two months, your CoD would be $400,000. Think of this as ‘opportunity cost’ in economic terms.

However, it may be argued that this cost is theoretical. How do you determine it when you haven’t actually done these jobs before?

Therefore, Scaled Agile recommends the following components for arriving at the CoD:

• User-business value – Do users consider this job valuable? What positive impact does it have on your business?

• Time criticality – Is there a deadline and how is the value above hurt when such isn’t met?

• Risk reduction/opportunity enablement value – Does this reduce delivery risk or will it open doors to new opportunities?

You assess initiatives against each component, assigning to them scores on a scale, say, of 1-10. When you have ratings for all three components, add them up to get the CoD for each job.

Job Duration

This is how long it will take you to complete a job. It can be somewhat hard to establish job duration, particularly in the early stages when it’s hard to tell how everything would go. Job size is, therefore, commonly used as a proxy.

Using the size approach, you can assign numbers to initiatives according to an already decided method. Items with lower numbers usually have higher priorities.

Prioritizing with WSJF

After estimating CoD and job duration, things are pretty straightforward from then on. You can now proceed to decide the overall WSJF scores for your initiatives. For each initiative, divide the Cost of Delay by the job duration (or size). Jobs with higher CoD or lower duration scores, relative to others, tend to have higher priorities. You can arrange the jobs in a table along with their WSJF scores for easy comparison after your calculations. Those with the highest ratings will top the list of your initiatives.

This technique makes it more inspiring to get seemingly complex jobs done. It lets you split such into smaller parts to contest with other smaller jobs.