S-CURVE
THE S-CURVE
Introduction
The first time most project managers become aware of the existence of S Curves is when they are requested by the client or senior management to include one in their next progress report. The following explains what the mysterious S Curve is, why it is an important project management tool, and how to generate one.
What is a S Curve?
A S Curve is defined as "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, which is typical of most projects. The beginning represents a slow, deliberate but accelerating start, while the end represents a deceleration as the work runs out."
Source: Wideman Comparative Glossary of Common Project Management Terms v2.1 Copyright R. Max Wideman, May 2001
Types of S Curves
There are a variety of S Curves that are applicable to project management applications, including...
* Man Hours versus Time S Curve
* Costs versus Time S Curve
* Baseline S Curve
* Actual S Curve
* Target S Curve
* Value and Percentage S Curves
Man Hours versus Time S Curve
The Man Hours versus Time S Curve is appropriate for projects that are labour intensive. It shows cumulative man hours expended over time for the duration of the project. As man hours are a product of man power and working hours, these may be adjusted together or individually in an attempt to keep the project on schedule. Projects may require additional man hours to finish on time due to low productivity, delays and disruptions, rework, variations, etc.
Figure 1: Man Hours versus Time S Curve
Costs versus Time S Curve
The Costs versus Time S Curve is appropriate for projects that contain labour and non-labour (e.g. material supply / hire / subcontract) tasks. It shows cumulative costs expended over time for the duration of the project, and may be used to assist in the calculation of the project's cashflow,
Introduction
The first time most project managers become aware of the existence of S Curves is when they are requested by the client or senior management to include one in their next progress report. The following explains what the mysterious S Curve is, why it is an important project management tool, and how to generate one.
What is a S Curve?
A S Curve is defined as "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, which is typical of most projects. The beginning represents a slow, deliberate but accelerating start, while the end represents a deceleration as the work runs out."
Source: Wideman Comparative Glossary of Common Project Management Terms v2.1 Copyright R. Max Wideman, May 2001
Types of S Curves
There are a variety of S Curves that are applicable to project management applications, including...
* Man Hours versus Time S Curve
* Costs versus Time S Curve
* Baseline S Curve
* Actual S Curve
* Target S Curve
* Value and Percentage S Curves
Man Hours versus Time S Curve
The Man Hours versus Time S Curve is appropriate for projects that are labour intensive. It shows cumulative man hours expended over time for the duration of the project. As man hours are a product of man power and working hours, these may be adjusted together or individually in an attempt to keep the project on schedule. Projects may require additional man hours to finish on time due to low productivity, delays and disruptions, rework, variations, etc.
Figure 1: Man Hours versus Time S Curve
Costs versus Time S Curve
The Costs versus Time S Curve is appropriate for projects that contain labour and non-labour (e.g. material supply / hire / subcontract) tasks. It shows cumulative costs expended over time for the duration of the project, and may be used to assist in the calculation of the project's cashflow,