7.6 Who should estimate?
The person managing the project is not necessarily the best one to prepare the estimates, although they should be closely involved, both as a source of information and because they need a clear understanding of what the estimates mean and what the estimators assume about outputs, inputs and the transformation process. If there are others who have more experience or more knowledge about some of the areas of work, these people may be the best ones to make estimates for the project or parts of it. Ask each person to work independently and then meet to compare estimates and to discuss how to arrive at realistic figures for revenues and costs. Similarly, it is often helpful to involve other perspectives to ensure that you have not forgotten revenues and costs that arise as part of carrying out areas of work unfamiliar to you.
If there is someone associated with the project with experience of estimating it could be very valuable to involve them. Taking advice about any risks relating to the revenues and costs can be helpful; for example, if you will need to buy materials, the prices of raw materials might vary over time or according to the quantity of the order. In a large project, the services of an experienced buyer might contribute cost savings.