SOFTWARE COST ESTIMATION
It is the responsibility of the project manager to make accurate estimations of effort and cost. This is particularly true for projects subject to competitive bidding where a bid too high compared with competitors would result in loosing the contract or a bid too low could result in a loss to the organisation . This does not mean that internal projects are unimportant. From a project leaders estimate the management often decide whether to proceed with the project. Industry has a need for accurate estimates of effort and size at a very early stage in a project. However, when software cost estimates are done early in the software development process the estimate can be based on wrong or incomplete requirements. A software cost estimate process is the set of techniques and procedures that an organisation use to arrive at an estimate. An important aspect of software projects is to know the cost, The major contributing factor is effort.
Why SCE is difficult and error prone ?
- Software cost estimation requires a significant amount of effort to perform it correctly.
- SCE is often done hurriedly, without an appreciation for the effort required.
- You need experience at developing estimates, especially for large projects.
- Human bias i.e An Estimator is likely to consider how long a certain portion of the system would take, and then to merely extrapolate this estimate to the rest of the system, ignoring the non-linear aspects of software development.
The causes of poor and inaccurate estimation
- imprecise and drifting requirements
- new software projects are nearly always different form the last.
- software practitioners don't collect enough information about past projects.
- estimates are forced to match the resources available.