Since launching the report in 2015, the Procuring Infrastructure PPPs team has relied on cutting-edge research on the latest PPP practices around the world, as well as frequent consultations with PPP experts in various economies. As an initial step, the team conducted an extensive literature review to firmly document internationally accepted good practices, as well as understand challenges that governments and private companies face when entering into a PPP project (see Bibliography). The team also consulted with the project's Expert Consultative Group (ECG), which includes seasoned PPP specialists, academics, and individuals from the private sector. By supplementing the extensive literature with the consultations, the team was able to refine the 2018 survey, ultimately producing a set of questions that comprehensively measure global PPP good practices and enable robust cross-economy analysis.