Spatial inequality in developing countries is due to the natural advantages of some regions relative to others and to the presence of agglomeration forces, leading to clustering of activity. This paper reviews and develops some simple models that capture these first and second nature economic geographies. The presence of increasing returns to scale in cities leads to urban structures that are n...

Economists disagree about the factors driving the substantial increase in residual wage inequality in the U.S. over the past few decades. We identify and estimate a general model of log wage residuals that incorporates: (i) changing returns to unobserved skills, (ii) a changing distribution of unobserved skills, and (iii) changing volatility in wages due to factors unrelated to skills. Using da...

Commonly used sums-of-squares-based error or deviation statisticsdlike the standard deviation, the standard error, the coefficient of variation, and the root-mean-square errordoften are misleading indicators of average error or variability. Sums-of-squares-based statistics are functions of at least two dissimilar patterns that occur within data. Both the mean of a set of error or deviation magn...

We present new evidence on levels and trends in after-tax income inequality in Canada between 1980 and 2000. We argue that existing data sources may miss changes in the tails of the income distribution, and that much of the changes in the income distribution have been in the tails. Our data are constructed from Census files, which are augmented with predicted taxes based on information availabl...

We discuss averaged turbulence modeling of multi-scales of length for an incompressible Newtonian fluid, with the help of the maximum information principle. We suppose that there exists a function basis to decompose the turbulent fluctuations in a flow of our concern into the components associated with various spatial scales and that there is a probability density function f of these fluctuatio...

Decomposition methods suggest major contributors to variability in returns to New York dairy farms are purchased feed quantities and milk production; milk price variability contributes substantially less. Decomposing the Gini measure of income inequality indicates that milk revenues and purchased feed expenditures contribute most to farm return inequality over time.

Recent years have seen widespread use of small-area maps based on census data enriched by relationships estimated from household surveys that predict variables, such as income, not covered by the census. The purpose is to obtain putatively precise estimates of poverty and inequality for small areas for which no or few observations are available in the survey. We argue that to usefully match sur...

This paper uses data on individual earnings in manufacturing industry for five African countries in the early 1990s to test whether firms located in the capital city pay higher earnings than do firms located elsewhere, and whether such benefits accrue to all or only certain types of workers. Earnings equations are estimated that take into account worker characteristics (education and tenure) an...

The quasistatic problem of elastoplasticity with combined kinematic-isotropic hardening is formulated as a time-dependent variational inequality (VI) of the mixed kind, that is, it is an inequality involving a nondiierentiable functional and is imposed on a subset of a space. This VI diiers from the standard parabolic VI in that time derivatives of the unknown variable occurs in all of its term...