Project schedule variance (PSV)

Projects are temporary, coordinated efforts undertaken to create defined outputs or outcomes within agreed constraints. Unlike continuing operations, they have an authorised beginning and end. Because much organisational change is delivered through projects, schedule performance is an important—but incomplete—view of execution.

When to use it

• Answer the key performance question: “To what extent are our projects delivered on schedule?”
• Include the KPI in the operational processes and supply-chain perspective.
• Establish the baseline, unit of time, data process, reporting frequency and tolerance before calculation.
• Compare results with approved milestones, relevant project classes and the organisation’s own forecasting history.

Origins

Comparing actual and planned completion dates is a basic project-control practice rather than a measure attributable to one inventor. The PSV in this article is a simple duration variance. It is different from earned value management’s schedule variance, which compares earned value with planned value and is expressed in monetary units.

What it is

Perspective: Operational processes and supply chain perspective.

Key performance question: To what extent are our projects delivered on schedule?

Monitoring schedule performance supports current intervention, future estimating and early detection of deviation. It should be considered with three questions:

1. Is the project on schedule?
2. Is the project on budget?
3. Is it delivering the specified scope and outcomes at the required quality?

A schedule result without budget and outcome context can be misleading. Finishing early may reflect efficient delivery, but it can also indicate conservative planning or omitted work.

Historical projects illustrate how large schedule changes can accompany cost escalation. London’s new Wembley stadium opened in 2007 after originally being scheduled for 2003. The Sydney Opera House was scheduled to open in 1963 for $7 million and opened in 1973 at a reported cost of $102 million.

PSV compares scheduled completion time with actual completion time. A result of zero means the project finished on the planned duration; a negative result indicates it took longer; and a positive result indicates it finished sooner. Define whether the inputs represent elapsed duration, working days or dates, and apply the same calendar to both.

How to use it

Measurement