14,293 research outputs found
Finite Sample Properties of Moran's I Test for Spatial Autocorrelation in Probit and Tobit Models - Empirical Evidence
In this paper, we investigate the finite sample properties of Moran’s I test statistic for spatial autocorrelation in limited dependent variable models suggested by Kelejian and Prucha (2001). We analyze the socio- economic determinants of the availability of dialysis equipment in 5,507 Brazilian municipalities in 2009 by means of a probit and tobit specifica- tion. We assess the extent to which evidence of spatial autocorrelation can be remedied by the inclusion of spatial fixed effects. We find spa- tial autocorrelation in both model specifications. For the probit model, a spatial fixed effects approach removes evidence of spatial autocorrelation. However, this is not the case for the tobit specification. We further fill a void in the theoretical literature by investigating the finite sample prop- erties of these test statistics in a series of Monte Carlo simulations, using data sets ranging from 49 to 15,625 observations. We find that the tests are unbiased and have considerable power for even medium-sized sample sizes. Under the null hypothesis of no spatial autocorrelation, their em- pirical distribution cannot be distinguished from the asymptotic normal distribution, empirically confirming the theoretical results of Kelejian and Prucha (2001), although the sample size required to achieve this result is larger in the tobit case than in the probit case.
Thermofield-Bosonization on Compact Space
We develop the construction of fermionic fields in terms of bosonic ones to
describe free and interaction models in the circle, using thermofielddynamics.
The description in the case of finite temperature is developed for both normal
modes and zero modes. The treatment extends the thermofield-bosonization for
periodic space
Canonical Transformations in a Higher-Derivative Field Theory
It has been suggested that the chiral symmetry can be implemented only in
classical Lagrangians containing higher covariant derivatives of odd order.
Contrary to this belief, it is shown that one can construct an exactly soluble
two-dimensional higher-derivative fermionic quantum field theory containing
only derivatives of even order whose classical Lagrangian exhibits chiral-gauge
invariance. The original field solution is expressed in terms of usual Dirac
spinors through a canonical transformation, whose generating function allows
the determination of the new Hamiltonian. It is emphasized that the original
and transformed Hamiltonians are different because the mapping from the old to
the new canonical variables depends explicitly on time. The violation of
cluster decomposition is discussed and the general Wightman functions
satisfying the positive-definiteness condition are obtained.Comment: 12 pages, LaTe
Workplace Romance and Fraternization Policies
With the ever increasing number of hours Americans spend at work, many are finding romance at the workplace. What should the employer consider when deciding whether and to what extent it should control romantic relationships between supervisors and subordinates and among co-workers? This paper addresses some of the social and legal issues surrounding these relationships and whether fraternization policies are a viable tool for handling the complex human issue of romance in the workplace
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