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Frequently Asked Questions



Interpreting the CPI

Changes in scores between 2005 and 2006

Using the CPI

Transparency International's CPI and the fight against corruption


What is the Corruption Perceptions Index?

The Transparency International Corruption Perceptions Index (CPI) ranks countries in terms of the degree to which corruption is perceived to exist among public officials and politicians. It is a composite index, a poll of polls, drawing on corruption-related data in expert surveys carried out by a variety of reputable institutions. The CPI reflects views of business people and analysts from around the world, including those of experts who are living in the countries evaluated.Transparency International commisssions the CPI from Johann Graf Lambsdorff, a university professor based in Passau, Germany.

For the purpose of the CPI, how is corruption defined?

The TI CPI focuses on corruption in the public sector and defines corruption as the abuse of public office for private gain. The surveys used in compiling the CPI ask questions that relate to the misuse of public power for private benefit, for example bribery of public officials, kickbacks in public procurement, embezzlement of public funds) or questions that probe the strength of anti-corruption policies, thereby encompassing both administrative and political corruption.

Why is the CPI based only on perceptions?

It is difficult to assess the overall levels of corruption in different countries based on hard empirical data, e.g. by comparing the amount of bribes or the number of prosecutions or court cases. In the latter case, for example, such comparative data does not reflect actual levels of corruption; rather it highlights the quality of prosecutors, courts and/or the media in exposing corruption across countries. One strong method of compiling cross-country data is therefore to draw on the experience and perceptions of those who are most directly confronted with the realities of corruption in a country.


How many countries are included in the CPI?

The CPI 2006 ranks 163 countries. In 2005, the CPI included 159 countries.

Why are some countries no longer reported in the CPI, and why are new countries included?

TI requires at least three sources to include a country in the CPI. The change in country coverage in the CPI 2006 relates to the fact that a new source, the World Bank's Country Policy and Institutional Assessment (CPIA) has been included, while two sources (Columbia University's State Capacity Survey and Information International's Survey of Middle Eastern Businesspeople) are now more than two years old and have been dropped from this year's CPI.

The omission of these older surveys has resulted in the following countries being removed from the CPI: Afghanistan, Fiji, Liberia, Palestine and Somalia. The inclusion of the CPIA and the increase of country coverage by PERC, however, have allowed the TI CPI 2006 to include the following new countries: Bhutan, Central African Republic, Dominica, Timor-Leste, Grenada, Guinea, Macao, Mauritania and Togo.

Which countries might be included in future CPIs?

Countries or territories with two sets of data are: Afghanistan, Antigua and Barbuda, Bahamas, Bermuda, Cape Verde, Cayman Islands, Comoros, Djibouti, Fiji, Guinea-Bissau, Liberia, Maldives, Palestine, Puerto Rico, Samoa, Sao Tome and Principe, Somalia, St. Lucia, St. Vincent & the Grenadines, Samoa, Sao Tome & Principe and Somalia. For all of the above countries / territories, at least one more set of data is necessary for inclusion in the CPI.

Countries or territories with only one set of data are: Andorra, Anguilla, Aruba, Brunei, French Guiana, Guadeloupe, Kiribati, Liechtenstein, Martinique, Netherlands Antilles, North Korea, Solomon Islands, St. Kitts & Nevis, Solomon Islands, Tonga, Vanuatu and Virgin Islands (US). For all of the above countries / territories, at least two more sets of data are necessary for inclusion in the CPI.

What are the sources of data for the CPI?

The CPI 2006 draws on 12 different polls and surveys from 9 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 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. For a full list of survey sources, details on questions asked and number of respondents for the CPI 2006, please see the detailed document on the CPI methodology at or

Whose opinion is polled for the surveys used in the CPI?

The expertise reflected in the CPI scores draws on an understanding of corrupt practices held by those based in both the industrialised and developing world. Surveys are carried out among business people and country analysts. The surveys used in the CPI use two types of samples, both non-resident and resident. It is important to note that residents' viewpoints correlate well with those of non-resident experts.

Does the CPI reproduce what it is propagating?

The TI CPI has gained wide prominence in the international media since its first publication in 1995. This has raised concern that respondents' judgements may be oveshadowed by the data reported by TI, which would introduce a problem of circularity. This hypothesis was tested using a survey question posed to business leaders around the world. Based on more than 9000 responses, knowledge of the CPI does not induce business experts to "go with the herd". Knowledge of the CPI may motivate respondents to determine their own views. This is a strong indication that there is no circularity in the present approach.

Has the methodology of the CPI 2006 changed?

There has been a small change to the methodology used in 2006. The CPI 2006 no longer reflects a three-year moving average, but now uses only two years of data. Therefore, the TI CPI 2006 uses data only from 2005 and 2006. The reason for this methodological change was to rely more on topical data. While this change does not make the CPI a measure of up-to-date anti-corruption policies, it may improve the ability of the individual country assessments to reflect recent developments, without lowering measurement precision.

How does TI ensure quality control of the CPI?

The CPI methodology is reviewed by an Index Advisory Committee consisting of leading international experts in the fields of corruption, econometrics and statistics. Members of the committee make suggestions for improving the CPI, but the management of TI takes the final decisions on the methodology used.

Interpreting the CPI

Which matters more, a country's rank or its score?

While ranking countries enables TI to build an index, a country's score is a much more important indication of the perceived level of corruption in a country. A country's rank can change simply because new countries enter the index or others drop out.

Is the country with the lowest score the world's most corrupt country?

No. The country with the lowest score is the one where corruption is perceived to be greatest among those included in the list. There are more than 200 sovereign nations in the world, and the latest CPI 2006 ranks 163 of them. The CPI provides no information about countries that are not included.

Example: What is implied by Haiti's ranking in the CPI 2006?

Corruption in Haiti has been perceived to be the highest in the CPI 2006. This does not, however, indicate that Haiti is the 'most corrupt country' or that Haitians are the 'most corrupt people'. While corruption is indeed one of the most formidable challenges to good governance, development and poverty reduction in Haiti, the vast majority of the people are only victims of corruption. Corruption by a limited number of powerful individuals, and failure of leaders and institutions to control or prevent corruption, does not imply that a country or its people are most corrupt.

Can country scores in the CPI 2006 be compared to those in past CPIs?

The index primarily provides a snapshot of the views of business people and country analysts for the current or recent years, with less of a focus on year-to-year trends. If comparisons with previous years are made, they should only be based on a country's score, not its rank, as outlined above.

Year-to-year changes in a country's score can either result from a changed perception of a country's performance or from a change in the CPI's sample and methodology. The only reliable way to compare a country's score over time is to go back to individual survey sources, each of which can reflect a change in assessment.

Why isn't there a greater change in a particular country's score, given the strength or lack of anti-corruption reform, or recent exposure of corruption scandals?

It is difficult to improve a CPI score over a short time period. The CPI 2006 is based on data from the past two years, relating to perceptions that may have been formed even further in the past. This means that substantial changes in perceptions of corruption are only likely to emerge in the index over longer periods of time.

Changes in scores between 2005 and 2006

Which countries' scores deteriorated most between 2005 and 2006?

Making comparisons from one year to another is problematic, for the reasons highlighted above. However, to the extent that changes can be traced back to individual sources, trends can be cautiously identified. Noteworthy examples of deteriorations from CPI 2005 to CPI 2006 are Brazil, Cuba, Israel, Jordan, Laos, Seychelles, Trinidad & Tobago, Tunisia and the United States. In these cases, actual changes in perceptions occurred during the last two years.

Which countriesÕ scores improved most?

With the same caveats applied, on the basis of data from sources that have been consistently used for the index, improvements can be observed from 2005 to 2006 for Algeria, Czech Republic, India, Japan, Latvia, Lebanon, Mauritius, Paraguay, Slovenia, Turkey, Turkmenistan and Uruguay.

Using the CPI

Is the CPI a reliable measure of a country's perceived level of corruption?

The CPI is a solid measurement tool of perception of corruption. As such, the CPI has been tested and used widely by both scholars and analysts. The reliability of the CPI differs, however, across countries. Countries with a high number of sources and small differences in the evaluations provided by the sources (indicated by a narrow confidence range) convey greater reliability in terms of their score and ranking; the converse is also the case.

Is the CPI a reliable measure for decisions on aid allocation?

Some governments have sought to use corruption scores to determine which countries receive aid, and which do not. TI does not encourage the CPI to be used in this way. Countries that are perceived as very corrupt can not be written off -- it is particularly they who need help to emerge from the corruption-poverty spiral. If a country is believed to be corrupt, this should serve as a signal to donors that investment is needed in systemic approaches to fight corruption. And if donors intend to support major development projects in countries perceived to be corrupt, they should pay particular attention to 'red flags' and make sure appropriate control processes are set up.

Transparency International's CPI and the fight against corruption

How is the CPI funded?

Transparency International is funded by various governmental agencies, international foundations and corporations, whose financial support makes the CPI possible. Additional support for TI's measurement tools comes from Ernst & Young. TI does not endorse a company's policies by accepting its financial support, and does not involve any of its supporters in the management of its projects. For more on Transparency International's sources of funding, please see

What is the difference between the CPI and TI's Global Corruption Barometer?

The CPI assesses expert perceptions of levels of public sector corruption across countries, while the Global Corruption Barometer (see is concerned with attitudes toward and experiences of corruption among the general public.

What is the difference between the CPI and TI's Bribe Payers Index (BPI)?

While the CPI indicates perceived levels of corruption in countries, the BPI focuses on the propensity of firms from leading export countries to bribe abroad -- providing an indication of the 'supply side' of corruption. The most recent Bribe Payers Index was published in October 2006 and can be found under: