Vision

A clear vision of the projects objectives is important. A statement that describes these objectives should be agreed and produced with the support of the key team members. Be as ambitious as possible but avoid commitment to the impossible. Encourage team members to question every aspect of the vision. This will further validate it is workable.

Don't be afraid to compromise on your ideal if the agreed vision still fits comfortably within the objectives of the project.

A vision should always describe "what we are going to change and how we are are going to achieve it".

To be successful scope definition is vital. The objectives of the project and the scope necessary to achieve the objective must be agreed by all involved. As far as possible the scope of work throughout the project must remain consistent. Unless there are clear benefits (opportunities), change to scope or objectives should always be resisted. Any change (which we will deal with later) should always be considered as an increase to risk to the projects success.

Purpose

Expand on the vision statement to explain the project is going to do, how long it will take and how much it will cost. This statement should reflect the relative importance most appropriate. Time, cost and performance are the importance values here. Each of these drivers will have an effect on the other.