Tests in Censored Models when the Structural Parameters Are Not Identified

This paper presents tests for the structural parameters of a censored regression model with endogenous explanatory variables. These tests have the correct size even when the identification condition for the structural parameter is invalid. My approach starts from the estimation of the unrestricted parameters, which does not depend on the identification of the structural parameter. Next, I set up the optimal minimum distance objective function, from where I derive the tests. The proposed robust tests are implemented in many statistical software packages since they demand only the Tobit and the ordinary least squares estimation functions. By simulating their power curves, I compare the robust to the Wald and the likelihood ratio tests. A case of the labor supply of married women illustrates the use of the robust tests for the construction of confidence intervals.endogenous Tobit, weak instruments, minimum distance estimation, female labor supply

Political Parties and the Tax Level in the American States: A Regression Discontinuity Design

With a regression discontinuity design I show that the partisan identity of the majority in the state House of Representatives has no causal effect on the tax level. This result goes against recent findings in the political economy literature. In the state Senate I find a significant discontinuity in the tax level, but I also find a discontinuity in the density of the forcing variable - which implies that we can not interpret the discontinuity in the Senate as a causal relation. Another contribution of the paper is to investigate under which conditions slim majorities in the American states (as opposed to close election) are appropriate for a regression discontinuity design.Regression discontinuity design, Democrats, Republicans, divided government, line item veto, tax level.

Phase Transitions in One-dimensional Translation Invariant Systems: a Ruelle Operator Approach

We consider a family of potentials f, derived from the Hofbauer potentials, on the symbolic space Omega=\{0,1\}^\mathbb{N} and the shift mapping $\sigma$ acting on it. A Ruelle operator framework is employed to show there is a phase transition when the temperature varies in the following senses: the pressure is not analytic, there are multiple eigenprobabilities for the dual of the Ruelle operator, the DLR-Gibbs measure is not unique and finally the Thermodynamic Limit is not unique. Additionally, we explicitly calculate the critical points for these phase transitions. Some examples which are not of Hofbauer type are also considered. The non-uniqueness of the Thermodynamic Limit is proved by considering a version of a Renewal Equation. We also show that the correlations decay polynomially and that each one of these Hofbauer potentials is a fixed point for a certain renormalization transformation.Comment: in Journ. of Stat. Phys 2015; Jour of Stat Phys 201

H2H^2 regularity for the p(x)−p(x)-Laplacian in two-dimensional convex domains

In this paper we study the $H^2$ global regularity for solutions of the $p(x)-$Laplacian in two dimensional convex domains with Dirichlet boundary conditions. Here $p:\Omega \to [p_1,\infty)$ with $p\in Lip(\bar{\Omega})$ and $p_1>1$.Comment: 18 pages. Keywords: Variable exponent spaces. Elliptic Equations. $H^2$ regularit

An optimization problem for the first weighted eigenvalue problem plus a potential

In this paper, we study the problem of minimizing the first eigenvalue of the $p-$Laplacian plus a potential with weights, when the potential and the weight are allowed to vary in the class of rearrangements of a given fixed potential $V_0$ and weight $g_0$. Our results generalized those obtained in [9] and [5].Comment: 15 page