We consider an agent who has to repeatedly make choices in an uncertain and changing environment, who has full information of the past, who discounts future payoffs, but who has no prior. We provide a learning algorithm that performs almost as well as the best of a given finite number of experts...

We study the statistical properties of three estimation methods for a model of learning that is often fitted to experimental data: quadratic deviation measures without unobserved heterogeneity, and maximum likelihood with and without unobserved heterogeneity. After discussing identification...

We develop a coordination game to model interactions between fundamentals and liquidity during unstable periods in financial markets. We then propose a flexible econometric framework for estimation of the model and analysis of its quantitative implications. The specific empirical application is...

This paper proposes to estimate the covariance matrix of stock returns by an optimally weighted average of two existing estimators: the sample covariance matrix and single-index covariance matrix. This method is generally known as shrinkage, and it is standard in decision theory and in empirical...

This paper extends multivariate Granger causality to take into account the subspaces along which Granger causality occurs as well as long run Granger causality. The properties of these new notions of Granger causality, along with the requisite restrictions, are derived and extensively studied...

We apply a multilevel hierarchical model to explore whether an aggregation fallacy exists in estimating the income elasticity of health expenditure by ignoring the regional composition of national health expenditure figures. We use data for 110 regions in eight OECD countries in 1997: Australia,...

In this paper I explore the issue of nonlinearity (both in the data generation process and in the functional form that establishes the relationship between the parameters and the data) regarding the poor performance of the Generalized Method of Moments (GMM) in small samples. To this purpose I...

We apply a multilevel hierarchical model to explore whether an aggregation fallacy exists in estimating the income elasticity of health expenditure by ignoring the regional composition of national health expenditure figures. We use data for 110 regions in eight OECD countries in 1997: Australia,...

The goal of this paper is to estimate time-varying covariance matrices. Since the covariance matrix of financial returns is known to change through time and is an essential ingredient in risk measurement, portfolio selection, and tests of asset pricing models, this is a very important problem in...

In this paper we study the dynamic behavior of the term structure of Interbank interest rates and the pricing of options on interest rate sensitive securities. We posit a generalized single factor model with jumps to take into account external influences in the market. Daily data is used to test...