The S-Curve is a well-known tool used by project management professionals. The model consists of a display of cumulative labor hours, costs, or other variables plotted against time. The S-Curve aims to represent various expenditures of resources over the projected time of the project or as a means of depicting the real-time expenditure of resources. The curve helps monitor the progress of the project and helps compare it to the projected S-Curve to verify whether the project is being completed within the time or budget limitations.
The model gets its name from the shape that is derived in the graph. The graph tends to be flat at the beginning and end and steep in the center. This is how most project timelines would be depicted. Various software-scheduling packages that can automatically generate S-Curves are now available
The S-Curve tool is used by many applications in the project management scenario. Some of them include target, cost, time, baseline, etc. To suit all needs, slight variations can be made to the basic S-Curve. Some of these are:
- Cost vs. Time S-Curve: This S-Curve is suitable for projects that contain both labor and non-labor tasks.
- Man Hours vs. Time S-Curve: This S-Curve is suitable for projects that contain labor tasks.
- Value and Percentage S-Curve: This S-Curve is useful for calculating the project's actual percentage.
- Target S-Curve: This S-Curve reflects the progress of the project if all tasks are completed as scheduled.
- Actual S-Curve: This S-Curve is ideal to measure the actual progress of the project until date.
To generate the S-Curve, it is important to plot the baseline and production schedule for each task. The baseline contains information about the actual start date and finish date. This variable could also contain information on person-hours and costs. The production schedule contains information of the actual percentage that is complete.
If done accurately, the S-Curve represents the project schedule that depicts how the project deliverables and resource assignments have been scheduled. The shape of the curve can provide a feedback on the project plan by highlighting some of the potential issues of the planning. The tool proves to be useful during the initial stages of planning and helps report progress against the plan or baseline. The analysis of the "actual progress to-date curve" against the "baseline curve" facilitates the achievement of project goals by providing a warning when the project is going astray from the baseline.
Read on to the next page for an example of how to create an S-Curve.