Singapore - One of the least Corrupt Countries (New Corruption Index Released)

This is what their website says about their data sources,

A. DATA SOURCES TO CALCULATE THE CPI

1. All sources of information used to construct the CPI are produced by reputable organisations and data gathering organisations. To be included in the CPI, a source must measure the overall extent of corruption (frequency and/or size of corrupt transactions) in the public and political sectors and provide a ranking of countries, that is to say, measure perceptions of corruption in at least a few different countries. Also, the methodology used to assess these perceptions has to be the same for all assessed countries in order for the source to be selected. The number of surveys/assessments included might vary from one year to another depending on their availability at the time of the development of the index.

The CPI 2010 is calculated using data from 13 different surveys or assessments produced by the following 10 independent organisations2:

1. Africa Development Bank- Country Policy and Institutional Assessments 2009 (AFDB 2009)
2. Asian Development Bank -Country Performance Assessment Ratings 2009 (ADB 2009)
3. Bertelsmann Foundation- Bertelsmann Transformation Index (BF 2009)
4. Economist Intelligence Unit -Country Risk Service and Country Forecast 2009 (EIU 2010)
5. Freedom House -Nations in Transit 2009 (FH 2010)
6. Global Insights, formerly World Markets Research Centre- Country Risk Ratings 2009 (GI 2010)
7. Institute for Management Development - World Competitiveness Report 2009 and 2010 (IMD 2009 and IMD 2010)
8. Political and Economic Risk Consultancy, Hong Kong - Asian Intelligence 2009 and 2010 (PERC 2009 and PERC 2010).
9. World Economic Forum - Global Competitiveness Report 2009 and 2010 (WEF 2009 and WEF 2010)
10. World Bank - Country Policy and Institutional Assessments for IDA Countries (WB 2009)