1.0 INTRODUCTION

An S-Curve is a mathematical process or function that results in a S shaped

curve also called a Sigmoid Curve. S-curves are an important project management tool

because it allow the progress of a project to be traced visually over time, and form a historical

record of what has happened to date. The S-Curve is used in project management as a means

of representing the various costs of resources over the projected time of the project or as a

means of plotting the real-time expenditure of resources. It is also 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 limits. 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. Analyses of S-curves

allow project managers to quickly identify project growth, slippage, and potential problems

that could adversely impact the project if no remedial action is taken.

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 and Target S-curve. The Man Hours versus Time S-curve is

appropriate for projects that are labor intensive in which the project manager has to know the

cumulative amount of man hours worked at a specific stage of the project. As man-hours are

a product of manpower and working hours, these may be adjusted together or individually in

an attempt to keep the project on schedule. Due to the low productivity, delays and

disruptions, rework and variations, projects may require additional man-hours to finish on

time. The Costs versus Time S-curve is suitable for projects that contain labor and non-labor

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 cash flow, and cost to complete.

Figure 1: Man Hours versus Time S-curve Figure 2: Costs versus Time S-curve

Baseline S-curve is a schedule prepared outlining the planned distribution of

resources and the timing of tasks required to complete the project in a set time frame and

budget. This generate the planned progress and the schedule may require revision to reflect

the changed requirements if the project requirements change prior to commencement. Target

S-curve may be generated from the production schedule that reflects the actual progress of

the project to date. This S-curve reflects the ideal progress of the project if all tasks are

completed as currently scheduled. Actual S-curve may be generated from the production

schedule which is updated on a regular basis throughout the duration of the project. This S-

curve 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.

Figure 3: Baseline S-curve Figure 4: Target S-curve

Figure 5: Actual S-curve