Aims to explain how the process of estimating costs within a construction project requires accurate and unambiguous input information if is to provide a better perception of value for the client. Highlights the problems associated with incomplete information and how confusion can be eliminated. Presents case studies to illustrate some negative and positive aspects of current practice, and follows on with the lessons learned from case studies. Gives suggested actions to address the issues concerning incomplete information and some of the lessons learned. Explains how different methods of producing and evaluating cost and analysing value fit together.