Types of S-curves Actual S-curves
The Production Schedule is updated on a regular basis throughout the duration of the Project. These updates include revising of the Task Start Dates and Finish Dates, and updating of Task % Complete values.
Using this information, Actual S-curves may be generated. These S‑curves reflects the actual progress of the Project to date, and may be compared with the Baseline and Target S‑curves to determine how the project is progressing as compared to the original Baseline Schedule.
During the Project, Actual S-curves will terminate at the Cut Off Date.
Figure 3: Actual S-‑curve (showing Baseline S-curve for comparison)
What is the Cut Off Date?
The Cut Off Date is the date on which all Tasks were physically inspected to determine their % Complete values. For example, if all Tasks were inspected on Thursday the 4th of February 2016, the Production Schedule was updated on Friday the 5th of February 2016, and the Actual S‑curves were generated on Saturday the 6th of February 2016, the Cut Off Date should be set to Thursday the 4th of February 2016.
At the completion of the Project, with all Tasks 100% complete, the Actual S‑curves will terminate at the Project Completion Date, and be identical to the Target S‑curves. The Actual S‑curves will usually change shape over the duration of the Project due to changes to Task Start Dates and Finish Dates, Man Hours and/or Cost, and Task % Complete to date.
Changing the Cut Off Date after the Production Schedule has been updated
If the Actual S-curve is to be accurate, the Cut Off Date must be set to the date all the Project's Tasks were physically inspected for Task % Complete.
As shown below, the Project's Tasks were physically inspected on the 4th of February 2016. This is the Cut Off Date that should be used when generating Actual S‑curves.
Using an earlier or later Cut Off Date can dramatically alter the shape of the Actual S‑curve, as shown below. Generally, using an earlier Cut Off Date will push the Actual S‑curves higher, while using a later Cut Off Date will push the Actual S‑curves lower.
Figure 4: Example of Actual S-curves using different Cut Off Dates