Tue Gørgens

Testing a Parametric Function Against a Non‐Parametric Alternative in IV and GMM Settings

This paper develops a specification test for functional form for models identified by moment restrictions, including IV and GMM settings. The general framework is one where the moment restrictions are specified as functions of data, a finite-dimensional parameter vector, and a nonparametric real function (an infinite-dimensional parameter vector). The null hypothesis is that the real function is parametric. The test is relatively easy to implement and its asymptotic distribution is known. The test performs well in simulation experiments.

Semiparametric estimation of a censored regression model with an unknown transformation of the dependent variable

In this paper we develo psemiparametric estimators of L and y in the model L(Y) = min[b›X + U,C], where Y is a nonnegative dependent variable, X is a vector of explanatory variables, U is an unobserved random error term with unknown distribution function y, C is a random censoring variable, b is an unknown parameter vector, and L is an unknown strictly increasing function. This model includes as a special case the censored proportional hazards model with unobserved heterogeneity. Estimators of L and y already exist for the case where either L or y belongs to a known finite-dimensional parametric family, and methods for estimating b exist for the general case. In this paper we propose estimators of L and y which do not assume that L and y belong to known parametric families. We obtain their asymptotic distributions and investigate the small sample properties of the estimators by Monte Carlo simulation.

Reservation wages and working hours for recently unemployed US women

Abstract This paper estimates a structural model of job search behavior where jobs are characterized by both wages and working hours. Worker heterogeneity is taken into account by including covariates in the job offer distribution and the utility function. The estimates are bias-corrected using a statistical model of measurement error designed to accommodate recent evidence on the empirical distribution of measurement errors. The results suggest that the difference between full time and part time reservation wages vary from −16% to 31%, depending on the characteristics of the individual. The hypothesis that full and part time reservation wages are identical is rejected.

Average Derivatives for Hazard Functions

This paper develops semiparametric kernel-based estimators of risk-specific hazard functions for competing risks data. Both discrete and continuous failure times are considered. The maintained assumption is that the hazard function depends on explanatory variables only through an index. In contrast to existing semiparametric estimators, proportional hazards is not assumed. The new estimators are asymptotically normally distributed. The estimator of index coefficients is root-n consistent. The estimator of hazard functions achieves the one-dimensional rate of convergence. Thus the index assumption eliminates the “curse of dimensionality.†The estimators perform well in Monte Carlo experiments.I thank Denise Doiron for stimulating my interest in this research project and Catherine de Fontenay, Hans Christian Kongsted, Lars Muus, seminar participants, and two anonymous referees for comments on an earlier version of the paper. I gratefully acknowledge the hospitality of the University of Aarhus and the University of Copenhagen, where part of this research was undertaken.

Does the Effect of Incentive Payments on Survey Response Rates Differ by Income Support History

This paper asks which sub-groups of the population are affected by the payment of a small cash incentive to respond to a telephone survey. We find that an incentive improves response rates primarily amongst those individuals with the longest history of income support receipt. Importantly, these individuals are least likely to respond to the survey in the absence of an incentive. The incentive thus improves both average response rates and acts to equalize response rates across different socio-economic groups, potentially reducing non-response bias. Interestingly, the main channel through which the incentive appears to increase response rates is in improving the probability of making contact with individuals in the group with heavy exposure to the income support system.

Finding Employment After Migration: How Long Does It Take?

This book examines the role of immigration policy, and of economic and social policies involved in promoting the settlement of immigrants to Australia. It is based on research of two groups of recent immigrants who arrived six years apart during the 1990s holding a range of family reunion, skill and humanitarian visas.

Nonparametric comparison of regression curves by local linear fitting

This paper proposes a new nonparametric test for the hypothesis that the regression functions in two or more populations are the same. The test is based on local linear estimates using data-driven bandwidth selectors. The test is applicable to data with random regressors and heteroskedastic responses. Simulations indicate the test has good power.

Semiparametric estimation of single-index hazard functions without proportional hazards

This research develops a semiparametric kernel-based estimator of hazard functions which does not assume proportional hazards. The maintained assumption is that the hazard functions depend on regressors only through a linear index. The estimator permits both discrete and continuous regressors, both discrete and continuous failure times, and can be applied to right-censored data and to multiple-risks data, in which case the hazard functions are risk-specific. The estimator is root-n consistent and asymptotically normally distributed. The estimator performs well in Monte Carlo experiments. Copyright Royal Economic Society 2006

The Role of Mobility in Offsetting Inequality: A Nonparametric Exploration of the CPS

This paper explores how annual earnings mobility offsets annual earnings inequality, using matched CPS data. Mobility in the economy is estimated using nonparametric quantile regression, for which we adapt state-of-the-art smoothing techniques. Mobility is measured through the churning process (changes in earnings given initial earnings) in order to identify different mobility patterns for different earnings groups. For instance, upward mobility in high earners is far weaker than its converse, downward mobility for low earners. We assess the (positive or negative) contribution to offsetting of each pattern in mobility. Innovations in our approach also allow us to identify trends and minute changes in mobility, and to pinpoint which changes in mobility have offset the increases in inequality observed over the decades. Copyright 2002 by The International Association for Research in Income and Wealth.

Semiparametric estimation of censored transformation models

Many widely used models, including proportional hazards models with un- observed heterogeneity, can be written in the form (Y ) = min[ 0 X + U; C], where is an unknown increasing function, the error term U has unknown distribution function and is independent of X, C is a random censoring threshold, and U and C are conditionally independent given X. Thispaper develops new n 1=2 -consistent and asymptotically normal semiparametric esti- mators of and which are easier to use than existing estimators. Moreover, Monte Carlo results suggest that the mean integrated squared error of predic- tions based on the new estimators is lower than for existing estimators.Many widely used models, including proportional hazards models with unobserved heterogeneity, can be written in the form