An examination of the UK treasury's evidence base for cost and time overrun data in UK value-for-money policy and appraisal

UK government procurement policy rests on Treasury claims that the private finance initiative (PFI) has reduced cost and time overruns. We review the five studies cited by the Treasury in support of this claim and find that only one purports to compare PFI with traditional procurement. The results of this single study are uninterpretable because of selection bias, small sample size (only 11 out of 451 PFI projects are included) and fundamental flaws in the analysis. There is thus no evidence to support the Treasury cost and time overrun claims of improved efficiency in PFI. We conclude that Treasury appraisal guidance, the 'Green Book' which compares PFI with other methods of procurement, is not evidence based but biased to favour PFI.