Composite indicators are synthetic indices of individual indicators and are increasingly being used to rank countries in various performance and policy areas. Using composites, countries have been compared with regard to their competitiveness, innovative abilities, degree of globalisation and environmental sustainability. Composite indicators are useful in their ability to integrate large amounts of information into easily understood formats and are valued as a communication and political tool. However, the construction of composites suffers from many methodological difficulties, with the result that they can be misleading and easily manipulated. This paper reviews the steps in constructing composite indicators and their inherent weaknesses. A detailed statistical example is given in a case study. The paper also offers suggestions on how to improve the transparency and use of composite indicators for analytical and policy purposes ...