One of the key aspects of the approach to assessing VfM is the need to ensure that the quantitative VfM analysis is not considered in isolation - qualitative assessment, wider VfM factors and evidence based examples are central to decision making. It will be necessary to take account of previous delivery and experience of privately financed projects when Procuring Authorities are promoting the future procurement of infrastructure assets. In respect of the overall VfM judgement the following should be noted
• Marginal Results: Where the difference in the assessments of the conventional option and the privately financed option are marginal (small positive for or against) the outcome should not be interpreted as sufficient evidence for or against the use of private finance as a procurement route. In such cases more weight should be given to the qualitative rather than the quantitative assessment.
• Uncertainty and sensitivity analysis: Where there is a high level of uncertainty around inputs, or outputs are highly sensitive to the input variables, it is appropriate to place greater weight on the qualitative assessment or to invest more time and money in establishing higher confidence in the most critical assumptions. Procuring Authorities should in any event undertake appropriate sensitivity analysis.