1,721,152 research outputs found
On the estimation of covariance matrices using panel data artificial regressions
No full textThe use of artificial regressions to compute the variance of the difference of pairs of panel data estimators that cannot be ranked in terms of efficiency is considered. It is illustrated how it is possible to get (asymtotically) valid estimators of covariance matrices for differences between estimators when the assumption that the error term in the auxiliary model is IID is violated. We distinguish two possible deviations, one leading only to a non-spherical-within groups covariance matrix and the second leading to a non-spherical-between-groups covariance matrix also. It is shown to what extent the use of an artificial regression with panel data can lead to a robust estimator of the covariance matrix in the first case whereas it leads to a non valid estimator in the second. An alternative step by step procedure is presented
Urban Labor Economics: a book review
No full textBook Reviewed: Urban Labor Economics, By Yves Zenou. Cambridge University Press, New York . 2009. Xiii+509 pp. $34.9
Unobserved heterogeneity or measurement errors? Testing for correlated effects with measurement errors
No full textThis paper addresses the problem of endogenous regressors due to the presence of unobserved heterogeneity, when this is correlated with the regressors, and caused by regressors' measurement errors. A simple two-stage testing procedure is proposed for the identification of the underlying cause of correlation between regressors and the error term. The statistical performance of the resulting sequential test is assessed using simulated data
Juvenile delinquency and conformism
No full textThis article studies whether conformism behavior affects individual outcomes in crime. We present a social network model of peer effects with ex ante heterogeneous agents and show how conformism and deterrence affect criminal activities. We then bring the model to the data by using a very detailed data set of adolescent friendship networks. A novel social network-based empirical strategy allows us to identify peer effects for different types of crimes. We find that conformity plays an important role for all crimes, especially for petty crimes. This suggests that, for juvenile crime, an effective policy should be measured not only by the possible crime reduction it implies but also by the group interactions it engenders. © 2009 The Author. Published by Oxford University Press on behalf of Yale University. All rights reserved
Local analysis of economic disparities in Italy: A spatial statistics approach
No full textThe spatial variation of the value-added per hour worked across Italian NUTS3 areas is decomposed into a productivity effect and an occupational composition effect. By analysing patterns of spatial association of those different (but related) economic variables and by using different interaction schemes between locations, it is possible to identify local differences in economic outcomes and to draw some conclusions about their determinants. Geographical proximity is measured by travel time. The results signal the presence of intra-regional differences as significant as those between the major regions. Such differences may differ in terms of their underlying causes, even within regions. © 2007 Springer-Verlag
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