Those who are fade up with TIB's perception-based corruption study may find a new book (2008) by Global Integrity and the UNDP very useful.
'A users' guide to measuring corruption' examines the state of the art of corruption measurement.It challenges some long held assumptions about what a good corruption metric looks like.
According to a blogpost of Global Integrity, the book contains the follwoing “good practices” in measuring corruption:
• Clearly define the unit of analysis – know what you are measuring;
• Break down ambitious goals of “measuring corruption” into more discrete and clearly defined variables;
• Focus on “actionable” data that can inform policy choices;
• Look for data that capture the voices of the poor and minority groups;
• Combine quantitative data with qualitative political-economy analysis;
• Engage national actors and use local sources of information whenever possible; and
• Be transparent in constructing a methodology for measuring corruption.
The case-studies also highlight the challenges anti-corruption and governance practitioners commonly face including:
• The current lack of corruption metrics that are useful in day-to-day policy and programmatic work;
• The need for more disaggregated data that move beyond single-country rankings to more discrete measures within sectors and institutions; and
• The need to move beyond perceptions-based data as the basis for corruption measurement.
The book is avaiable here for download.