A range of alternative empirical definitions of informal activity have been employed in the literature. Choice of definition is often dictated by data availability. Different definitions may imply very different conceptual understandings of informality. In this paper the authors investigate the degree of congruence between three definitions of informality based on employment contract registration, social security protection, and the characteristics of the employer and employment using Brazilian household survey data for the period 1992 to 2001. The authors present evidence showing that 64 percent of the economically active population are informal according to at least one definition, but only 40 percent are informal according to all three. Steady compositional changes have been taking place among informal workers, conditional on definition. The econometric analysis reveals that the conditional impact of particular factors (demographic, educational attainment, and family circumstances) on the likelihood of informality varies considerably from one definition to another. The results suggest growing heterogeneity within the informal sector. Therefore, the authors argue that informal activity may be as much associated with entrepreneurial dynamism as with any desire to avoid costly contract registration and social protection. However, the authors confirm there is no a priori reason for entrepreneurial activity to be unprotected. Consequently definitions of informality based on occupation and employer size seem the most arbitrary in practice even if conceptually well-founded.
