A. All PPPs were combined into a single database (the 'Master Database').
B. Each project was assigned a unique ID. This was done by removing duplicates, removing additional sections of the same PPP (e.g. project extensions), and removing secondary market financial transactions associated with the project. Where clear, projects from the databases which didn't fit our definition of a PPP were also removed. This cleansing was necessary to ensure the sample wasn't skewed when the Master Database was used to select the random sample, as each project had an equal chance of forming part of the study.
C. Projects with a transaction value of less than USD 20 million were removed. These were agreed to be too small for the purpose of the study.
D. The projects were sorted by region, sector and financial close period. The breakdown categories were as follows:
Region: UK and Europe, North America, Latin America and the Caribbean, East Asia (including China), South and Central Asia, South-East Asia and the Pacific, Australia and New Zealand, Middle East and North Africa, and Sub-Saharan Africa)
Sector: Transport (including rail, roads, airports and ports), energy (including renewable and non-renewable generation, and distribution), water (including supply and distribution) and waste (including solid waste, waste to energy and waste water treatment)
Financial close (be period): Period 1 (January 2005 to September 2007), Period 2 (October 2007 to June 2010), Period 3 (July 2010 to March 2013) and Period 4 (April 2013 to December 2015)
The breakdowns of the overall population of relevant PPPs by Region, Sector, and Financial Close period are displayed in Appendix A (Data analysis).