In 1994 new surveys were carried out of the extent of the undeclared sector in Denmark, together with a study of the reliability of the interview methods used and the comparability of the results obtained across surveys at different dates. This material is presented in The Shadow Economy in Denmark, supplemented by an examination of the usefulness of other research methods.
Research Taxation and Undeclared Work
The Shadow Economy in Denmark 1994. Measurement and Results
Study paper no. 3