WHO SHOULD PERFORM THE ESTIMATE
The consensus view is that people who are directly involved with the implementation are involved in the estimate. In industry most commonly a supervisor or manager is in the charge of producing cost estimates. They either perform this on their own or consult with programmers. A study carried out by [JEFFERY] indicated that if the programmers are involved in the estimation it was more accurate and the programmers had more motivation to meet the targets that they had set. This is further complemented by a recent study carried out by [LEDERER].
An opposing view is that the estimate should be performed by an independent cost estimation team who can provide an unbiased estimate. The enthusiasm of some estimators can be balanced by the caution of others, but the dangers of this group activity is that some estimators can dominate. Also when you remove the individual responsibility from a task, a group are more likely to adopt a riskier course of action. To reduce this problem the Delphi Approach can be used which will aim to remove the politics from the estimation, as estimates are anonymous and not biased.
A publication by [DeMARCO] discusses estimation teams in more detail. DeMarco suggests that an estimating group should be set up, separating it from the development stage. The estimators would then have no personal stake in the development and their performance would be based on the groups ability to develop estimates that converge quickly to the actual costs of a project.
