The Hidden Economy: State And Prospects For Measurement1

To know the size and development of the hidden or underground economy is important for policy making, mainly because the measures undertaken may be misdirected if they are based on biased official statistics. The hidden economy can be measured by considering indicators. The direct methods are based on voluntary surveys and on tax auditing and other compliance methods. The indirect estimation methods rely on the identification of residuals with respect to income and expenditures, as well as in the labor and money markets. The strengths and weaknesses of each of these measurement approaches are discussed and the resulting estimates of the size of the hidden economy are compared. A different approach to measurement is to look at the determinants leading to the existence and growth of the hidden economy. Finally, the method of “unobserved variables” allows the combination of the two approaches by simultaneously considering the determinants and indicators of the under‐ ground economy. The results show a considerable range of sizes for a given country and year. Though there is a broad range of size estimates, there is general agreement that the hidden economy's size has been growing for all countries over recent decades. Further progress in quantitative knowledge about the hidden economy requires the development of a theoretical model which analyses the interdependencies between the official private sector, the hidden economy, and the public sector.