Section N ‘S’ Curves

Plotting the work done (man hours, orders placed, money spent, or percentage progress) against time produces the ‘S’ curve shape. Unfortunately the indications they provide are retrospective; nevertheless, they indicate the status of the project and help to forecast where the project is going.

As well as the overall ‘S’ curve, individual curves for design/engineering, the purchase of materials and equipment, and construction should be plotted to give an overall picture of the status of the project

A common flaw with any progress measurement system (that needs careful monitoring) is that people will perform the easy items of work first. This is because that is how they get measured/rewarded with the progress recorded on the ‘S’ curve.

In the early stages of the project (when the basic controls are still being established), it is difficult to obtain the realistic data needed to create meaningful curves. Nevertheless, it is important to analyse the health of the project as soon as possible in the launch phase. Some suggested diagnoses of typical project situations are shown below.

1 Interpreting the Curves


Case 1—see Figure V.N.1: In the diagram, the man hours used and the actual progress are coincidental, but progress is way behind schedule.

What's wrong?


If the man hours used and the progress are matching, then there is nothing wrong with the productivity—it's 100 per cent. So, the answer must be that not enough man hours are being ...

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