This is Transparency International's product and the organisation takes full responsibility for it. The methodology is reviewed in consultation with an international TI Steering Committee of academics and professionals. Transparency International has tended to focus on corruption in the public sector and define corruption as the abuse of public office for private gain. The CPI makes no effort to reflect private sector fraud. The surveys used in compiling the CPI tend to ask questions in line with the misuse of public power for private benefits, with a focus, for example, on bribing of public officials, taking kickbacks in public procurement or embezzling public funds, etc.
Complaints are understandable.
No government wants to see its country depicted as being corrupt. It is an index that seeks to portray perceptions of corruption in countries. Governments that do not like the results should not question the merits of the CPI, rather they should question why their countries are widely seen as being corrupt. If the perceptions consistently reproduce similar assessments it is a good indicator that they are not just referring to cultural or geographical biases but to a real-world phenomenon. The high correlation between the sources we use has actually increased in the past 3 years.