Wednesday, July 1, 2009

S-Curve


Sample project s Curve


An S-Curve is a sigmoid function, that is a mathematical process or function that results in a S shaped curve also called a Sigmoid Curve. The S-Curve is used in project management as a means of representing the various expenditures of resources over the projected time of the project or as a means of charting the real-time expenditure of resources. This is important to project management in that it can be used to monitor the project as is progresses and compare it to the projected S-Curve to determine whether or the project is being completed within the time and budget limitations. These resources might be the cumulative cost of the project, the number of man hours required at any given stage in the project, the expenditure of raw materials for construction or assembly, etc.

The term S-Curve can also be used to indicate an S shaped chart resulting from a cumulative likelihood distribution. In this function, an S-Curve is a tool of quantitative risk analysis which project management would use to determine the possible dangers of any given course of action.

This term is defined in the 3rd and the 4th edition of the PMBOK.



The S Curve is a well known project management tool and it consists in "a display of cumulative costs, labour hours or other quantities plotted against time".The name derives from the S-like shape of the curve, flatter at the beginning and end and steeper in the middle, because this is the way most of the projects look like.

The S curve can be considered as an indicator and it's used for many applications related to project management such as: target, baseline, cost, time etc. That's why there is a variety of S Curves such as:
-Cost versus Time S Curve;(appropriate for projects that contain labour and non-labour tasks).
-Target S Curve;(This S Curve reflects the ideal progress of the project if all tasks are completed as currently scheduled)
-Value and Percentage S Curves;(Percentage S Curves are useful for calculating the project's actual percentage complete)
-Actual S Curve;(This S Curve reflects the actual progress of the project to date)

In order to be able to generate a S Curve, A Baseline and Production Schedule are necessary because they contain important information for each task: -the Baseline - contains information about Actual Start date and finish date.
-The Baseline - can also contain information about Man Hours and costs.
-The Production Schedule contains information about the actual percentage complete.

There are some software scheduling packages that generate automatically S Curves. For example MS Project does not have this possibility so a third party software application is needed to process the Baseline and Production Schedule data and generate the needed S Curve.( for example S Curve Generator that integrates with MS EXcel to generate S Curves).


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