Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonparametric methods for inference in the presence of instrumental
  variables   We suggest two nonparametric approaches, based on kernel methods and
orthogonal series to estimating regression functions in the presence of
instrumental variables. For the first time in this class of problems, we derive
optimal convergence rates, and show that they are attained by particular
estimators. In the presence of instrumental variables the relation that
identifies the regression function also defines an ill-posed inverse problem,
the ``difficulty'' of which depends on eigenvalues of a certain integral
operator which is determined by the joint density of endogenous and
instrumental variables. We delineate the role played by problem difficulty in
determining both the optimal convergence rate and the appropriate choice of
smoothing parameter.

3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn