There are by now vast academic literatures on both tax compliance and the underground economy. These literatures provide estimates of the overall degrees of non-compliance and shadow (or hidden) activity as well as numerous insights into their causes and consequences. However, we believe it is fair to say that they provide an incomplete perspective on the characteristics of the individuals or groups who engage in such behaviors. Methods for evaluating shadow activity are frequently based on indirect measures, such as discrepancies in national account or labor force statistics, trends in the demand for currency or in monetary transactions, or variations over time in national electricity consumption.
Working Paper Number 03-19.