Weighted Shortest Job First framework

We're building a comprehensive knowledge library about product development as part of our mission. The library is for anyone looking to make better decisions — primarily decisions about how to further develop a product. Whether you're an inventor, a product manager, or a Chief Product Officer, using a structured decision-making method increases your chances of building the right things for the right audience (build the right thing for the right audience). Today we'll introduce the Weighted Shortest Job First (WSJF) framework.

Basic Information

Framework name: Weighted Shortest Job First (WSJF).

Inventor: Don Reinertsen.

Year of first use: 2009.

Link to the author's original research:

1. The book The Principles of Product Development Flow: Second Generation Lean Product Development (2009).

Key figures in the framework's development:

1. Dean Leffingwell.

Key milestones in the framework's development:

1. The book The Principles of Product Development Flow: Second Generation Lean Product Development (2009).

2. Added to SAFe in 2012 and adopted across larger organizations.

History of First Use

WSJF is a framework for maximizing Return on Investment (ROI) in product management. It mainly helps decide "in what order to develop particular features so that they have the maximum impact on the economic return of development." The method is based on the Shortest Job First principle, developed back in the 1970s. The framework is also often called Cost of Delay Divided by Duration.

Basic Prioritization Principles

The goal of WSJF is to prioritize further development based on two parameters:

• Feature weight = the weight of a feature, calculated from Cost of Delay, which in product development is computed in two ways:

  • The first way is to use the Cost of Delay framework.

  • The second way is a calculation based on other parameters (always the sum of all values), collectively also called Cost of Delay:

    • Economic value = business value, i.e. an estimate of the "economic value of a feature" expressed financially.

    • Time value = Time value, i.e. an estimate of the "time value of a feature — how much its value declines over time" expressed financially.

    • Risk/Opportunity = Risk reduction/opportunity, i.e. an estimate of "how a feature eliminates risk and opens up new possibilities" expressed financially.

• Feature duration = feature duration can be calculated in two ways:

  • Prioritization of already started features and products = duration here means the shortest time needed to finish the features development. What matters is how long developing a partially completed feature will tie up our resources, because that is exactly when Cost of Delay accrues.

  • Prioritization of new features and products = duration here means which piece of functionality has the greatest economic return.

  • In both cases the value can be expressed in Story Points, in units of time, or relatively (small / medium / large).

We score each potential new feature or product against the feature weight and feature duration parameters. We then plug the resulting values into the formula below.

The highest values represent the greatest benefit for further development (more precisely, the features with the highest values should be built first). These ideas therefore become the winners.

Prioritization Example

It's important to add that the definitions of the values must be the same across all evaluated features and products, otherwise the comparison won't make sense. The values must also always be current.

WSJF directly gives us the order in which we should develop features or new products. The resulting order often does not reflect how long a customer has been waiting for a given feature, because the ranking is determined by the feature's economic return.

Another important factor in the final development decision is feature duration.

• If we applied prioritization to features already in development, we're answering the question: "Isn't there a better order for the features I'm already developing, given their economic return? Should I, for example, work on finishing feature B instead of feature A?"

• If we used duration for new features, we're answering the question: "Which features have the greatest economic return?"

Visual Prioritization Example

Feature weight

• Feature weight is most often the Cost of Delay value, i.e. a numeric financial figure, for example $1,000.

Feature duration

• Feature duration might be, for example, 40 days.