The Corruption Perceptions of the Transparency International measures the perceived levels of public sector corruption worldwide. The findings are less than encouraging. Not a single country comes close to top marks, while over 120 countries score below 50 on the scale of 0 (highly corrupt) to 100 (very clean). This means less than a third of countries are even above the midpoint.
Corruption hurts all countries. In the index’s lower-scoring countries, people frequently face situations of bribery and extortion, rely on basic services that have been undermined by the misappropriation of funds, and confront official indifference when seeking redress from authorities that are on the take. In higher-scoring countries the situation may seem less obvious in the daily lives of citizens, but closed-door deals, illicit finance, and patchy law enforcement exacerbate many forms of corruption at home and abroad.
The Corruption Perceptions Index aggregates data from a number of different sources that provide perceptions of business people and country experts of the level of corruption in the public sector.
Standardise data sources to a scale of 0-100 where a 0 equals the highest level of perceived corruption and 100 equals the lowest level of perceived corruption.
This is done by subtracting the mean of the data set and dividing by the standard deviation and results in z-scores, which are then adjusted to have a mean of approximately 45 and a standard deviation of approximately 20 so that the data set fits the CPI’s 0-100 scale. The mean and standard deviation are taken from the 2012 scores, so that the rescaled scores can be compared over time against the baseline year.