Assumptions and method
Uses equal time intervals and a strictly increasing cumulative baseline. Plateaus and changed baselines need separate treatment.
Test a scenario
Use the result in a decision
Use a common baseline, measurement boundary and status date.
Uses equal time intervals and a strictly increasing cumulative baseline. Plateaus and changed baselines need separate treatment.
Set a baseline and change one assumption to compare outcomes.
A worked example
Follow the fixed teaching example
- EV 300 lies between baseline values 250 at period 2 and 400 at period 3.
- Earned schedule = 2 + (300 − 250)/(400 − 250) = 2.3333 periods. Compare with actual time 3, giving −0.6667 periods.
These illustrative inputs describe a project scenario, not a published benchmark. All monetary inputs use the same currency and price basis.
- Cumulative planned values at time 0, 1, 2…
- 0, 100, 250, 400, 500
- Earned value
- 300
- Actual elapsed periods
- 3
- Earned schedule
- 2.3333 periods
- Time-based schedule variance
- -0.6667 periods
- Time-based schedule index
- 0.7778
Interpret the output only within the assumptions above. Changing the inputs changes the result; it does not validate the inputs.
Source & credit
Walt Lipke introduced earned schedule in “Schedule Is Different” (2003).
Walt Lipke: original earned-schedule papers
This is independently written code and explanation of the underlying method. The linked publication, its diagrams and its trademarks remain its owner’s material; no permission to reuse them is implied.