Concept: Earned Schedule is the time at which the value currently earned should have been earned. To calculate the amount of Earned Schedule, compare the Earned Value (BCWP) at the actual time to the Planned Value (BCWS) at the end of each time period in the schedule. Count the number of time periods in which the Earned Value is greater than or equal to the Planned Value. Add in any fractional amount. [1]
Practice: The Earned Schedule metric (ES) is the basis for an array of associated metrics (SPIt, EACt, TSPI, P Factor, and others). Beyond that, ES is a useful measure in its own right. At ProjectFlightDeck, we’ve found that it is best expressed in an artifact adapted from the Agile framework: the Burndown Chart.
In a Schedule Burndown Chart, the vertical scale represents the total number of periods remaining in the project. The horizontal scale represents the periods.
The Expected Burndown line is the baseline for time utilization, running straight from the first period to the last planned period. The ES Burndown line shows how much time has actually been earned, extending from the first period to the last scheduled period.
To get the ES Burndown, the total remaining time is decremented by the amount of schedule that is earned up to the end of each period.
If the ES Burndown line is above the Expected Burndown line, the project is late. If the ES Burndown line is below the Expected Burndown line, the project is early.
If the project is late, the total number of periods will grow greater than the number of planned periods. Hence, in the chart, both Burndown lines start at 8 remaining periods, rather 10. To finish, two periods were added to the schedule beyond the ones in the baseline.
Similarly, the Expected Burndown line finished two periods before the end, reflecting the fact that it took 10 periods to earn the value expected in 8 periods.
The next post describes the Pro’s and Con’s of the ES metric.
[1] To find the fractional amount, divide the amount of value earned in the fractional period alone by the amount of value planned for the same period.
|
