On defining and measuring the informal sector

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.Labor Markets,Labor Standards,Work&Working Conditions,Labor Management and Relations,Tertiary Education

Human capital and earnings inequality in Brazil, 1988-98 : quantile regression evidence

The authors undertake an empirical examination of rates of return to human capital for men in Brazil, through the period of macroeconomic stabilization and trade liberalization, using data from the 1988, 1992, and 1998 Brazilian household surveys (Pesquisa Nacional por Amostra de Domic?os, PNAD). The authors estimate simultaneous quantile equations to gain an insight on the impact of human capital on wages across the hourly earnings distribution. They conclude that there is evidence of growing inequality in rates of return to education in Brazil. But the authors find evidence that education is no longer used as a screening device in the labor market, but rather rewarded for its innate association with higher productivity. Although increases in rates of return to education have been more pronounced at the top of the earnings distribution, this has not led to increased inequality. This is because the levels of education and other labor market-rewarded endowments have increased and offset the rate of return effect.Public Health Promotion,Decentralization,Health Monitoring&Evaluation,Curriculum&Instruction,Teaching and Learning,Economic Theory&Research,Fiscal&Monetary Policy,Curriculum&Instruction,Teaching and Learning,Health Monitoring&Evaluation

Gender wage differentials in Brazil : trends over a turbulent era

Since the late 1980s, macroeconomic and trade reform in Brazil appears to have been accompanied by a substantial improvement in the position of women compared with men in the labor market, despite only modest changes to labor market institutions. The authors examine movements in the gender wage gap from 1988 to 1998. Their findings indicate that, over this period, the gender wage gap fell mainly because of reduced discrimination against women. But the authors find evidence to suggest that, more recently, since the elimination of high inflation, human capital investments and other earnings-related enhancements have begun to improve women's condition.Public Health Promotion,Anthropology,Health Monitoring&Evaluation,Gender and Development,Population&Development,Anthropology,Agricultural Knowledge&Information Systems,Environmental Economics&Policies,Health Monitoring&Evaluation,Population&Development

Isospin-breaking two-nucleon force with explicit Delta-excitations

We study the leading isospin-breaking contributions to the two-nucleon two-pion exchange potential due to explicit Delta degrees of freedom in chiral effective field theory. In particular, we find important contributions due to the delta mass splittings to the charge symmetry breaking potential that act opposite to the effects induced by the nucleon mass splitting.Comment: 10 pages, 4 figure

Depleted pyrochlore antiferromagnets

I consider the class of "depleted pyrochlore" lattices of corner-sharing triangles, made by removing spins from a pyrochlore lattice such that every tetrahedron loses exactly one. Previously known examples are the "hyperkagome" and "kagome staircase". I give criteria in terms of loops for whether a given depleted lattice can order analogous to the kagome \sqrt{3} \times \sqrt{three} state, and also show how the pseudo-dipolar correlations (due to local constraints) generalize to even the random depleted case.Comment: 6pp IOP latex, 1 figure; Proc. "Highly Frustrated Magnetism 2008", Sept 2008, Braunschwei

Effective Hamiltonian and low-lying energy clustering patterns of four-sublattice antiferromagnets

We study the low-lying energy clustering patterns of quantum antiferromagnets with p sublattices (in particular p=4). We treat each sublattice as a large spin, and using second-order degenerate perturbation theory, we derive the effective (biquadratic) Hamiltonian coupling the p large spins. In order to compare with exact diagonalizations, the Hamiltonian is explicitly written for a finite-size lattice, and it contains information on energies of excited states as well as the ground state. The result is applied to the face-centered-cubic Type I antiferromagnet of spin 1/2, including second-neighbor interactions. A 32-site system is exactly diagonalized, and the energy spectrum of the low-lying singlets follows the analytically predicted clustering pattern.Comment: 17 pages, 4 table

Charge-Symmetry-Breaking Three-Nucleon Forces

Leading-order three-nucleon forces that violate isospin symmetry are calculated in Chiral Perturbation Theory. The effect of the charge-symmetry-breaking three-nucleon force is investigated in the trinucleon systems using Faddeev calculations. We find that the contribution of this force to the 3He - 3H binding-energy difference is approximately 5 keV.Comment: 14 pages, 3 figure