What are the sources of data for the CPI?
The CPI 2008 draws on 13 different polls and surveys from 11 independent institutions. TI strives to ensure that the sources used are of the highest quality and that the survey work is performed with complete integrity. To qualify, the data must be well documented and sufficient to permit a judgment on its reliability. All sources must provide a ranking of nations and must measure the overall extent of corruption. This condition excludes surveys which mix corruption with other issues, such as political instability, decentralization or nationalism for instance. Data for the CPI has been provided to TI free of charge. Some sources do not allow disclosure of the data that they contribute; other sources are publicly available.
