Earned Schedule (ES) is a project management technique that enhances traditional Earned Value Management (EVM) methods by providing a time-based perspective on schedule performance. While EVM focuses on cost variance and performance, ES extends these concepts to schedule analysis by calculating sch…Earned Schedule (ES) is a project management technique that enhances traditional Earned Value Management (EVM) methods by providing a time-based perspective on schedule performance. While EVM focuses on cost variance and performance, ES extends these concepts to schedule analysis by calculating schedule performance indicators in units of time rather than cost. This allows for a more accurate assessment of schedule adherence and project completion forecasting.
The core concept of Earned Schedule involves determining the time at which the earned value of work was actually accomplished. By comparing this to the actual time spent, project managers can calculate schedule variance (SV) and schedule performance index (SPI) in time units. For example, a positive schedule variance indicates the project is ahead of schedule, while a negative variance signifies delays. This time-based analysis addresses limitations in traditional EVM, where SPI loses sensitivity as projects progress beyond the halfway point.
Earned Schedule provides several benefits in progress measurement and reporting. It offers a more intuitive understanding of schedule performance, as time-based metrics are often easier for stakeholders to interpret. ES allows for improved forecasting of project completion dates using methods like the Independent Estimate at Completion (IEAC), which considers actual performance trends. Additionally, ES supports proactive management by highlighting schedule issues early, enabling timely corrective actions.
In practice, integrating Earned Schedule into project reporting enhances the effectiveness of schedule control processes. It complements cost-based EVM metrics, providing a comprehensive view of project health. By adopting ES, project managers can improve communication with stakeholders, make better-informed decisions, and increase the likelihood of project success by effectively managing time-related performance.
Earned Schedule (ES) in PMI-SP: Understanding, Application, and Exam Preparation
Introduction to Earned Schedule
Earned Schedule (ES) is an extension of Earned Value Management (EVM) that provides a time-based perspective of project performance. While traditional EVM metrics (SPI and CPI) effectively measure cost performance throughout a project's lifecycle, SPI tends to converge to 1.0 as projects near completion, even if they're substantially behind schedule. Earned Schedule addresses this limitation by expressing schedule variance in time units rather than cost units.
Why Earned Schedule is Important
Earned Schedule gives project managers a more accurate picture of schedule performance, especially in later project stages. Its importance stems from:
• Providing reliable schedule indicators throughout the entire project lifecycle • Offering more intuitive measurements expressed in time units (days, weeks, months) • Enabling more accurate forecasting of project completion dates • Supporting better decision-making through clearer understanding of time-based performance
How Earned Schedule Works
Earned Schedule determines when the current earned value should have been achieved according to the plan. Key components include:
1. Time Measures: • Actual Time (AT): The current point in time from project start • Earned Schedule (ES): The time at which the current Earned Value (EV) should have been earned according to the plan • Planned Duration (PD): The total planned duration of the project
2. ES Calculation: ES is determined by finding the time point on the planned value curve where the current earned value falls. It involves identifying the time increment where EV crosses the PV curve.
3. ES-Based Performance Metrics: • Schedule Variance (time) - SV(t) = ES - AT • Schedule Performance Index (time) - SPI(t) = ES ÷ AT • Independent Estimate at Completion (time) - IEAC(t) = PD ÷ SPI(t)
Interpreting ES Metrics
• SV(t) > 0 and SPI(t) > 1.0: Project is ahead of schedule • SV(t) = 0 and SPI(t) = 1.0: Project is on schedule • SV(t) < 0 and SPI(t) < 1.0: Project is behind schedule
Unlike traditional SPI, SPI(t) continues to reflect accurate schedule performance until project completion, making it valuable for late-stage decision-making.
ES in Practice: A Simple Example
Consider a 10-month project. At month 6 (AT = 6): • The planned value (PV) should be $60,000 • The actual earned value (EV) is $45,000 • Looking at the PV curve, an EV of $45,000 should have been achieved at month 4.5 • Therefore, ES = 4.5 • SV(t) = 4.5 - 6 = -1.5 months (behind schedule) • SPI(t) = 4.5 ÷ 6 = 0.75 (progressing at 75% of planned rate) • IEAC(t) = 10 ÷ 0.75 = 13.33 months (forecasted completion)
Exam Tips: Answering Questions on Earned Schedule
1. Focus on conceptual understanding: • Understand that ES expresses schedule performance in time units • Recognize how ES differs from traditional EVM schedule metrics • Know why ES provides better insights as projects approach completion
2. Remember key formulas: • ES = The time point where current EV would have occurred according to plan • SV(t) = ES - AT • SPI(t) = ES ÷ AT • IEAC(t) = PD ÷ SPI(t)
3. Calculation strategies: • Draw a quick PV/EV graph to visualize where EV crosses the planned timeline • Break down calculations step-by-step when solving exam problems • Double-check units (ensure all time measures use consistent units)
4. Watch for scenario-based questions: • Apply ES concepts to determine if corrective actions are needed • Use ES forecasts to justify recommendations for project changes • Compare ES results with traditional EVM metrics to explain differences
5. Common exam mistakes: • Confusing SPI and SPI(t) interpretations • Mixing time and cost units in calculations • Applying ES when traditional EVM metrics would be more appropriate
By mastering Earned Schedule concepts and calculations, you'll be well-prepared to answer PMI-SP exam questions that test your understanding of advanced schedule management techniques.