| Summary: | This dissertation is composed of three essays regarding the finite sample properties of estimators
for nonparametric models.
In the first essay we investigate the finite sample performances of four estimators for additive
nonparametric regression models - the backfitting B-estimator, the marginal integration M-estimator
and two versions of a two stage 2S-estimator, the first proposed by Kim, Linton and
Hengartner (1999) and the second which we propose in this essay. We derive the conditional
bias and variance of the 2S estimators and suggest a procedure to obtain optimal bandwidths
that minimize an asymptotic approximation of the mean average squared errors (AMASE). We
are particularly concerned with the performance of these estimators when bandwidth selection is
done based on data driven methods. We compare the estimators' performances based on various
bandwidth selection procedures that are currently available in the literature as well as with the
procedures proposed herein via a Monte Carlo study.
The second essay is concerned with some recently proposed kernel estimators for panel data
models. These estimators include the local linear estimator, the quasi-likelihood estimator, the pre-whitening estimators, and the marginal kernel estimator. We focus on the finite sample properties
of the above mentioned estimators on random effects panel data models with different within-subject
correlation structures. For each estimator, we use the asymptotic mean average squared
errors (AMASE) as the criterion function to select the bandwidth. The relative performance of the
test estimators are compared based on their average squared errors, average biases and variances.
The third essay is concerned with the finite sample properties of estimators for nonparametric
regression models with autoregressive errors. The estimators studied are: the local linear,
the quasi-likelihood, and two pre-whitening estimators. Bandwidths are selected based on the
minimization of the asymptotic mean average squared errors (AMASE) for each estimator. Two
regression functions and multiple variants of autoregressive processes are employed in the simulation.
Comparison of the relative performances is based mainly on the estimators' average squared
errors (ASE). Our ultimate objective is to provide an extensive finite sample comparison among
competing estimators with a practically selected bandwidth. === Graduation date: 2006
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