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Often overlooked, early estimation is essential to indicate the potential size and scope of a project or package of work. This can then be used to make a rational judgement of its viability and a reasonable assessment of the potential costs.
The difficulty with accurate estimating is greatest early in the life of a project when there is the least knowledge of the requirements, yet this is when estimates are most important.
How early is early?
It is almost never too early. A soon as the first high level requirements and constraints are known a rough estimate can be produced. As requirements become better understood more techniques can be employed to refine the estimates.
What do we estimate?
The starting point is to estimate the size (ideally in Function Points) of whatever is to be developed. In addition appropriate historical data must be identified for likely productivity and costs per Function Point. From these, cost estimates, likely duration and staffing profiles can be derived.
SMS Early Estimating services include:
- Discovery of high level requirements and constraints - through consultancy and/or workshops
- Identification of suitable historical data
- Analysis using a basket of estimating models.
Whenever possible at least three different models are used and their results compared to give an estimate and indication of confidence.
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