1.22 This guidance provides a series of qualitative considerations that should frame the approach to the quantitative VfM assessment, with the intention being that the quantitative assessment is used as a support tool for making an overall assessment. It is important that the outputs from the quantitative or qualitative assessment should not be considered in isolation as a standalone case for, or against, PFI.
1.23 The following should be noted:
• Marginal Results: Where the difference in the results for the conventional option and PFI option are marginal (small positive for or against PFI) the figures should not be interpreted as sufficient evidence for or against use of PFI as a procurement route. In such cases more weight should be given to the qualitative than the quantitative assessment.
• Uncertainty and level of sensitivity of results: Where there is a high level of uncertainty around inputs, or outputs are highly sensitive to the input variables, it is appropriate to accord greater weight to 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.
1.24 In all cases, the overall assessment must note an appropriate and thorough explanation of the leading factors in both the quantitative and qualitative analyses in coming to a decision, especially where the two assessments do not appear supportive of one another.