Key Delay Metrics

Understanding schedule delay isn’t as simple as comparing end dates between updates. A project might still show the same completion date from one period to the next, but that doesn’t necessarily mean everything stayed on track. To truly assess performance, you need to look deeper into the drivers behind any end date movement.

SmartPM quantifies delays by analyzing variances in activity start and finish dates between consecutive schedule updates. This approach enables precise measurement of delays and their impact on the project's critical path.

End Date Variance

The most basic schedule analysis measures End Date Variance, the change in the schedule’s planned finish date from one update to the next. While this is a good starting point, it doesn’t tell the full story.

Even if the end date hasn’t shifted, delays may still have occurred within the schedule and been offset by other adjustments.

For example, if a critical path activity was delayed by 5 days due to lackluster progress, but another critical path activity in the plan was shortened by 5 days to compensate, the end date would appear unchanged. However, this tradeoff masks underlying schedule movement.

In SmartPM, this equation is:

End Date Variance = Actual Progress Impact – Planned Changes Impact

In Period Delay (Critical Path Delay)

In Period Delay represents delays that occurred between two successive schedule updates - or, a “window”. This measures how the end date should have been pushed by critical path work that did not achieve their planned durations or missed their planned start and/or finish dates.  If a critical path task is delayed, the project’s completion date is directly impacted. Tracking this metric helps identify where and why delays happened during the reporting period.

In SmartPM’s delay analysis, red bars indicate In Period Delay, showing where the project lost time compared to the baseline and previous update.

In Period Gains

In Period Gains capture the opposite effect; when work on the critical path is completed faster than planned or ahead of sequence. These gains can offset delays and help maintain (or even improve) the project’s end date.

In SmartPM’s delay analysis, green bars represent these gains, showing where the project outperformed the original plan.

Planned Impact

Planned Impact measures how updates and changes to remaining work affect the overall project completion date.

This represents adjustments made after the data date, in the plan. Changes such as shortening planned durations, stacking resources, or breaking sequences, will bring the end date in.  Adjustments like adding impact activities or fragnets, extending planned durations, or de-compressing the schedule will push the end date out.

In the delay analysis, blue bars reflect these changes, showing how schedule modifications to future work have shifted the forecasted end date.

Putting It All Together

When reviewing schedule performance, consider both what’s already happened (In Period Delay and In Period Gains) and what’s been changed going forward (Planned Impact).

Together, these metrics provide a clear picture of whether delays were experienced, mitigated, or simply masked through schedule adjustments, allowing you to identify true progress and risk behind the project’s headline end date.