|Español - Français - Italiano|
The nature of the development of projects and programmes is that the levels of activity increase to a peak during the delivery phase and then tail off towards closure.
This means that the consumption of money and resource similarly builds up to a peak and then declines.
When this is calculated cumulatively and represented graphically it usually has the shape of a horizontally stretched ‘S’ hence the term ‘S-Curve’.
Scheduling techniques such as critical path analysis provide earliest and latest dates when activities can be performed. These two sets of dates will provide different S-curves and if these are placed together they form an envelope.
The actual use of a resource or expenditure should track within the envelope as long as work proceeds within the bounds of the critical path schedule.
This can be useful in terms of planning stock levels for consumable resources or agreeing funding requirements.