The shadow or informal economy covers all economic activities which are hidden from official authorities for monetary, regulatory and institutional reasons. Although widely used, multiple indicator-multiple cause (MIMIC) models have been criticised, and we develop a modified model and database covering 157 countries over the years 1991 to 2017. We tested our model using satellite data on nocturnal light intensity as a proxy for the size of countries’ economies, and compared our results with the figures of 23 countries’ national statistical offices, finding stable and similar results. The average over all countries and over the whole period is 30.9% of GDP. The shadow economy is large in some regions (Latin America and sub-Saharan Africa) and there is sizeable heterogeneity within regions. On average, from 1991 to 2017 the shadow economy declined by 6.8%. In the short term the shadow economy has a negative impact on the official one and in the long term it has a positive effect.

This paper describes and criticizes the MIMIC estimation method due to a double counting problem; a correction is suggested. The measurement methods used for National Accounts Statistics are discussed – the discrepancy method and two new micro survey methods – are described and a third, a micro method, using a combination of company manager surveys and their knowledge to calibrate the size of the shadow economy in firms, is presented. A detailed comparison of the four micro estimation methods with the MIMIC and the corrected MIMIC method are offered. One major result is that the corrected MIMIC method, especially, comes quite close to various types of lately developed micro survey methods.

Estimates of the size of the shadow economy in 21 OECD countries are presented. The average size of the shadow economy (as a percentage of ‘official’ GDP) over 1999/2000 in these countries is 16.7%. The author concludes that it is the increasing burden of taxation and social security contributions, combined with rising state regulatory activities, that are the driving forces for the recent growth in size of the shadow economy in the countries concerned.