- What is the Corruption Perceptions Index (CPI)?
- Which countries/territories are included in the Corruption Perceptions Index (CPI)?
- What is corruption and how does the CPI measure it?
- Why is the CPI based only on perceptions?
- What are the data sources for the CPI?
- Can country/territory scores in the 2011 CPI be compared to those in past indices?
- Why are countries/territories removed from the index, and why are new countries/territories added?
- What is the difference between a country/territory’s rank and its score?
- Is the country/territory with the lowest score the world’s most corrupt nation?
- What other research does TI produce to analyse corruption?
1. What is the Corruption Perceptions Index (CPI)?
The CPI ranks countries/territories based on how corrupt their public sector is perceived to be. It is a composite index, a combination of polls, drawing on corruption-related data collected by a variety of reputable institutions. The CPI reflects the views of observers from around the world, including experts living and working in the countries/territories evaluated.
2. Which countries/territories are included in the Corruption Perceptions Index (CPI)?
For a country/territory to be included in the ranking it must be included in a minimum of three of the CPI’s data sources. Thus, inclusion in the index is not an indication of the existence of corruption but rather dependent solely on the availability of sufficient information.
3. What is corruption and how does the CPI measure it?
Corruption is the abuse of entrusted power for private gain. This is the working definition used by Transparency International (TI), applying to both the public and private sectors. The CPI focuses on corruption in the public sector, or corruption which involves public officials, civil servants or politicians. The data sources used to compile the index include questions relating to the abuse of public power and focus on: bribery of public officials, kickbacks in public procurement, embezzlement of public funds, and on questions that probe the strength and effectiveness of anti-corruption efforts in the public sector. As such, it covers both the administrative and political aspects of corruption. In producing the index, the scores of countries/territories for the specific corruption-related questions in the data sources are combined to calculate a single score for each country.
4. Why is the CPI based only on perceptions?
Corruption generally comprises illegal activities, which mainly come to light only through scandals, investigations or prosecutions. It is thus difficult to assess absolute levels of corruption in countries or territories on the basis of hard empirical data. Possible attempts to do so such as by comparing bribes reported, the number of prosecutions brought or court cases directly linked to corruption cannot be taken as definitive indicators of corruption levels. Rather they show how effective prosecutors, the courts or the media are in investigating and exposing corruption. One reliable method of compiling comparable country data is to capture perceptions of those in a position to offer assessments of public sector corruption in a given country.
5. What are the data sources for the CPI?
The 2011 CPI draws on 17 data sources from 13 institutions. The information used for the 2011 CPI is survey data from these sources gathered between December 2009 and September 2011. The CPI includes only sources that provide a score for a set of countries/territories and which measure perceptions of corruption in the public sector. TI ensures that the sources used are of the highest quality. To qualify, the data collection method must be well-documented and the methodology published to enable an assessment of its reliability. For a full list of data sources, questions asked, and the type of respondents for each country/territory, please see the CPI sources description document.
6. Can country/territory scores in the 2011 CPI be compared to those in past indices?
The CPI is not designed to allow for country scores to be compared over time. This is because the index draws on a country’s rank in the original data sources, rather than its score. A rank will always deliver only relative information – and therefore a ranking is a one off assessment. A country’s rank in a given data source can change a) if perceptions of corruption in other countries included in that source change or b) if countries are added or removed from that data source.
7. Why are countries/territories removed from the index, and why are new countries/territories added?
Countries/territories are only included in the index when three or more of the data sources assess the country/territory in question. When less than three data sources are available, countries cannot be included in the index. The 2011 index includes five more countries/territories than last year, due to the availability of country-level data. North Korea, the Bahamas, St Lucia, St Vincent and the Grenadines, and Suriname have entered the index in 2011.
8. What is the difference between a country/territory’s rank and its score?
A country/territory’s score indicates the perceived level of public sector corruption there on a scale of 0 - 10, where 0 means that a country is perceived as highly corrupt and 10 means that a country is perceived as very clean. A country’s rank indicates its position relative to the other countries/territories included in the index. It is important to keep in mind that a country’s rank can change simply because new countries enter the index or others drop out.
9. Is the country/territory with the lowest score the world’s most corrupt nation?
No. The CPI is mostly an assessment of perception of administrative and political corruption. It is not a verdict on the levels of corruption of entire nations or societies or of their policies and activities. Citizens of those countries/territories that score at the lower end of the CPI have shown the same concern about and condemnation of corruption as the public in countries that perform strongly. Further, the country/territory with the lowest score is the one where public sector corruption is perceived to be most prevalent among those included in the list. There are more than 200 sovereign nations in the world, and the 2011 CPI ranks 183 of them. The CPI provides no information about countries/territories that are not included.
10. What other research does TI produce to analyse corruption?
TI produces independent, empirical research on corruption. Our global research portfolio combines qualitative approaches with quantitative ones, macro-level indicators with in-depth diagnostics, expert analysis with experience, and also includes perceptions-based survey work. This body of research provides a comprehensive picture of the scale, spread and dynamics of corruption around the world. It also serves to mobilise and support evidence-based, effectively-tailored policy reform. Complementing the Corruption Perceptions Index, TI’s portfolio of global research includes:
Global Corruption Barometer (GCB): a representative survey of more than 70,000 households in nearly 90 countries on people’s perceptions and experiences of corruption. The most recent Global Corruption Barometer can be found at:
Bribe Payers Index (BPI): a ranking of leading exporting countries according to the perceived likelihood of their firms to bribe abroad. It is based on a survey of business executives focusing on the business practices of foreign firms in their country. The most recent Bribe Payers Index can be found at:
Global Corruption Report (GCR): a thematic report that explores corruption with regard to a specific sector or governance issue. The report provides expert research and analysis as well as case studies. The most recent Global Corruption Report can be found at:
National Integrity System assessments (NIS): a series of in-country studies providing an extensive assessment of the strengths and weaknesses of the key institutions that enable good governance and integrity in a country (the executive, legislature, the judiciary, and anti-corruption agencies among others). A full list of reports and more information on the National Integrity System model can be found at: