The National Audit Office (NAO) undertakes Value For Money (VFM) studies, which are used as the basis of evidence in hearings of the House of Commons Committee of Public Accounts. VFM studies are therefore integral to the process of accountability of public bodies to Parliament for their use of resources. This paper examines the production of VFM studies by the NAO, and in particular the ways in which audit teams arrive at their judgements. It introduces a theoretical frame-work which highlights: (i) the interplay of intuitive and analytical thinking as VFM teams assemble and interpret data and, (ii) the ways in which teams use three distinct types of judgement criterion in studies, based on the use of multiple empirical indicators about some event, the logical coherence of the auditee’s behaviour, and consensus about ‘what actually happened’.