This paper discusses survey techniques aimed at a better measurement of corruption at the micro level and argues that with appropriate survey methods and interview techniques, it is possible to collect quantitative micro-level data on corruption. Public expenditure tracking surveys, service provider surveys, and enterprise surveys are highlighted with several applications. These surveys permit measurement of corruption at the level of individual agents, such as schools, health clinics, or firms. They also permit the study of mechanisms responsible for corruption, including leakage of funds and bribery.

http://siteresources.worldbank.org/INTPEAM/Resources/PETS2.pdf