The quantitative assessment relies upon a sound evidence base, wherever possible built up from past procurement experience in relation both to NPD and conventional procurement routes. This evidence base needs to be continually refreshed by the incorporation of new information from projects at all stages of procurement and operation, particularly where there is a differential due to the procurement method. If the current evidence base is inadequate, then other information should be sought to justify the inputs into the model and steps taken to remedy this gap for future procurements.
Factors that are common in nature and economic effect to both procurement methods should be ignored.
If a value is imputed to any of these wider VfM factors, then that value must be explained and substantiated by the Procuring Authority. In all circumstances, a "base case" Conventional Procurement Assessment Model should be established which assumes like for like timing and equivalent specification and assumptions to that being delivered in the private sector bids. This will help to ensure that the impact of the assumptions about wider VfM factors is wholly transparent. Sensitivity testing of the assumptions about wider VfM factors should then be undertaken.