The IDR country studies were carried out in three stages between May and September 2014. The stages differ in depth and in scope. In Stage 1, a comprehensive database was compiled to include information on the structure, activities and outputs of statistical systems in all developing countries. Once this information was compiled, national statistical systems were divided into a small number of distinct groups with similar characteristics. Stage 2 involved a desk-study assessment including a questionnaire of a sample of countries from each of the groups, involving 29 countries in total (for details see ‘Country studies selection process’). Stage 3 involved in-depth investigation and analysis in seven countries, selected from each of the groups identified in Stage 1.