Begin with the decision

An appraisal should help you decide whether to proceed, renegotiate, investigate or walk away. Before adding detail, be clear about the question it needs to answer and the return or outcome you require.

Separate what you know from what you assume

A quoted construction cost, an estimated sales value and a hoped-for programme are different kinds of evidence. Label the source and confidence behind each major input. A tidy spreadsheet does not make an uncertain assumption more reliable.

Look for connected risks

A planning delay can change the funding period, holding costs and route to market. A design change can alter both cost and value. Test combinations of events as well as isolated changes; the relationships often matter more than the headline number.

Put a price on the uncertainty

Some gaps can be resolved before you commit. Others need to be reflected in the price, conditions, contingency or structure of the transaction. Decide which risks you can accept and which need a clear answer first.

Finish with the next action

The useful output is a decision and a short list of what must happen next. That may be further technical advice, a revised offer or a different scheme. More spreadsheet detail is only valuable if it improves the decision.