How can you measure the level of corruption in a country? If the abuse of public office for private gain is typically done in secret, under the table or behind closed doors, how can you systematically – and credibly – capture its scale and depth?
For nearly 20 years, campaigning NGO Transparency International has scored and ranked countries according to how corrupt their public sectors are perceived to be. The 2013 edition of its Corruption Perceptions Index (CPI) was published on Tuesday.
Drawing on 13 data sources, and based on the perceptions of businesspeople and country experts, the 2013 CPI gives 177 countries a score from zero to 100, where zero is a perception that the country's public sector is "highly corrupt" and 100 is "very clean".
Denmark and New Zealand top the list as the countries with the lowest perceived levels of public sector corruption; Afghanistan, North Korea and Somalia are the bottom three. More than two-thirds of the 177 countries examined scored below 50, a proportion similar to previous years.
Australia is labelled one of "the biggest decliners", alongside countries such as Syria, Libya, Mali, Spain, Mauritius, Iceland and Guatemala. The biggest improvers include Burma, Senegal, Nepal, Greece, and Lesotho.
Transparency International trumpets the CPI as "the most widely used indicator of corruption worldwide". The high-profile and widely reported index has, however, amassed its fair share of critics over the last two decades.
Some have attacked the CPI's reliance on the opinions of a small group of experts and businesspeople. This, says Alex Cobham, fellow at the Centre for Global Development, "embeds a powerful and misleading elite bias in popular perceptions of corruption" and can lead to inappropriate policy responses.
In an article for Foreign Policy, entitled Corrupting Perceptions, Cobham suggested earlier this year that Transparency International should drop the CPI and said it would be more useful to collect better evidence of actual corruption or information about how corruption is or isn't affecting citizens. "The index corrupts perceptions to the extent that it's hard to see a justification for its continuing publication," he said.
Others argue it is simply impossible to relay in a single number the scale and depth of a complex issue like corruption, and compare countries accordingly. "The index gets much-needed attention, but it overshadows [Transparency International's] other activities and exposes it to criticism," said the Economist in a 2010 article that dubbed the CPI the "murk meter".
Transparency International has defended its approach, arguing that capturing experts' perceptions is the most reliable method of comparing relative corruption levels across countries.
"Corruption generally comprises illegal activities, which are deliberately hidden and only come to light through scandals, investigations or prosecutions," says the NGO. "There is no meaningful way 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 studying court cases directly linked to corruption, cannot be taken as definitive indicators of corruption levels. Instead, they show how effective prosecutors, the courts or the media are in investigating and exposing corruption."
While the CPI may be Transparency International's most famous product, the NGO acknowledges it cannot tell the full story and now produces a range of other measures, including the Global Corruption Barometer, which looks at citizens' perceptions and experiences of corruption, and the Bribe Payers Index, which ranks exporting countries according to the perceived likelihood that their firms will bribe abroad.
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