9 Survey analysis was carried out using Excel and SPSS, excluding projects that had not provided data for a particular element of the analysis. In general, procuring authorities provided full responses. However, missing answers tended to be more common for questions that asked for quantification, such as the costs of tendering delays and the breakdown of costs of changes made to the project during the preferred bidder negotiations.
10 Some of the figures produced in this report, especially on tendering times, differ slightly from those contained in the 2006 Treasury publication, Strengthening Long-Term Partnerships. The average tendering time quoted by the Treasury is 27 months, compared to the 33 months quoted in this report. This is because the Treasury took a sample of projects based on the year in which they went to the market rather than, as for this study, the year in which they reached financial close. Whilst the Treasury approach had the advantage of enabling a clearer link to be made between policy initiatives and their effects on projects in procurement, it did mean that those projects with the longest procurement periods which had not yet reached financial close were not included.
11 We also carried out regression analysis to explore associations between key variables and the length and time of tendering, see Appendix 4.