The traditional approach of managing project performance is with the use of Earned Value Management. There is a recent trend towards the expansion of traditional Earned Value Management practices to include the concept of Earned Schedule.
Whereas Earned Value provides insight as to how the project is trending in relation to the plan by assessing cost and schedule variances, Earned Schedule focuses on the time element of schedule performance throughout the project execution phase.
Earned Value, although very effective at providing visibility to cost performance, is not as transparent when it comes to schedule performance over time. Case in point, at completion, irrespective as to how work progressed on the schedule (ahead or behind plan) at completion, the schedule performance index will always be 1.0.
Earned Schedule overcomes this drawback, providing useful tools to report on schedule performance, and providing visibility to the project state from which to base informed decisions.
To perform the analysis, Earned Schedule analysis incorporates detail from the baseline and forecast schedules as well as the integrated project management cost report (earned versus planned). In addition to looking at Earned Schedule metrics, other key metrics are factored into this approach to assess overall schedule performance.
Key metrics derived from the schedule and highlighted in this approach include:
• Critical Path Length Index (CPLI)
• Baseline Execution Index (BEI)
• Total Float Consumption Index (TFCI)
• To Complete Schedule Performance Index (TSPI)
• Predicted Forecast Finish Date (PFFD)
• Schedule Performance Index (time) (SPIt)
• Independent Estimate At Complete (time) (IEACt)
The intent of these metrics is to identify trends and assist in predicting project outcomes based on past performance. Since this approach is highly dependent on the schedule data, the more compliant a schedule is to industry best practices the better the quality of the results. The metrics are negatively impacted by recent re-baselining as this causes us to lose historical performance detail.
Frequent analysis of the schedule execution reporting metrics defined above provides transparency of project performance and brings visibility to early risk triggers in support of a proactive approach to project execution monitoring and control.
This paper will present a case study demonstrating how additional transparency through this approach highlighted a potential schedule risk. This increased visibility allowed the project team to reprioritize and implement proactive corrective actions to mitigate any potential impact to the project In Service Date (ISD).