What are you hoping to learn from the evaluation? What decisions do you expect to make as a result of the evaluation? What do you need to do to provide evidence of the completion of your project?

To clarify the purpose of your evaluation, start by identifying what you need to learn in the short and long term. Review your Evaluation SOW and Timeline.
Key items to think about when writing your purpose are:
Make sure to include decision makers, the decisions at hand, and projects being evaluated.
What are you hoping to learn from the evaluation?
What decisions do you expect to make as a result of the evaluation?
What do you need to do to provide evidence of the completion of your project?