Research

I currently focus on dynamic panel data models which allow for unobserved factors and network effects.

These models are relevant when the past affects the present, units influence each other (e.g. house prices in one city affect neighboring cities, what your friend does affects what you do etc.) and there are common unobserved shocks which affect everyone or a subset of the units.

Sample applications: house prices, unemployment, spread of behaviors on social networks, popularity of news topics and opinions in different regions of the country.

Double-Question Survey Measures for the Analysis of Financial Bubbles and Crashes

Joint work with Hashem Pesaran

Journal of Business & Economic Statistics, 38:2, 428-442

Summary

We develop a novel type of survey indicator which can be used to measure and forecast financial bubbles and crashes. We show how the application of our indicator improves the out of sample forecast of house prices across US Metropolitan Statistical Areas when compared to traditionally used methods.

Academic Abstract

This article proposes a new double-question survey whereby an individual is presented with two sets of questions; one on beliefs about current asset values and another on price expectations. A theoretical asset pricing model with heterogeneous agents is advanced and the existence of a negative relationship between price expectations and asset valuations is established, and is then tested using survey results on equity, gold, and house prices. Leading indicators of bubbles and crashes are proposed and their potential value is illustrated in the context of a dynamic panel regression of realized house price changes across key Metropolitan Statistical Areas (MSAs) in the U.S. In an out-of-sample forecasting exercise, it is also shown that forecasts of house price changes (pooled across MSAs) that make use of bubble and crash indicators perform significantly better than a benchmark model that only uses lagged and expected house price changes. Supplementary materials for this article are available online.

Downloads

The manuscript and supplemental material (data, code, appendices) can be downloaded here.

Estimation of Peer Effects in Endogenous Social Networks: Control Function Approach

Joint work with Roger Moon

The Review of Economics and Statistics 0 0:ja, 1-51

Summary

We propose a novel estimator of peer effects. Our estimator takes into account the fact that there may be unobserved characteristics which drive both link formation and behavior, which, if not taken into account, introduce bias into traditional types of peer effect estimators. We use a sieve semiparametric approach and establish asymptotics of the semiparametric estimator.

 

Academic Abstract

We propose methods of estimating the linear-in-means model of peer effects in which the peer group, defined by a social network, is endogenous in the outcome equation for peer effects. Endogeneity is due to unobservable individual characteristics that inuence both link formation in the network and the outcome of interest. We propose two estimators of the peer effect equation that control for the endogeneity of the social connections using a control function approach. We leave the functional form of the control function unspecified, estimate the model using a sieve semiparametric approach and establish asymptotics of the semiparametric estimator.

Estimation and Inference in Multivariate Spatiotemporal Models with Common Latent Factors

Joint work with Hashem Pesaran and Cynthia Fan Yang

Working paper

Summary

When analyzing processes which are correlated across space and time – such as house prices – it is important to take into account the fact that correlation might be induced by unobserved factors (common shocks) and “neighbor” effects (one unit affects another one). We propose a novel estimator which controls for both unobserved factors and spillover effects and apply it to forecasting house prices.

 

Academic Abstract

Coming soon

Downloads

Coming soon

Estimation and Inference for Spatial Models with Heterogeneous Coefficients in MATLAB, Python, R, and Stata

Joint work with Michele Aquaro, Federico Belotti and Giovanni Millo

Work in progress

The Informational Role of Housing Market Liquidity

Joint work with Michele Aquaro and Christian Badarinza

Work in progress

Spatial Equilibrium and Search Frictions – an Application to the New York Taxi Market

Working paper

Summary
Academic Abstract

This paper uses a dynamic spatial equilibrium model to analyze the effect of matching frictions and pricing policy on the spatial allocation of taxicabs and the aggregate number of taxi-passenger meetings. A spatial equilibrium model, in which meetings are frictionless but aggregate matching frictions can arise endogenously for certain parameter values, is calibrated using data on more than 45 million taxi rides in New York. It is shown how the set of equilibria changes for different pricing rules and different levels of aggregate market tightness, defined as the ratio of total supply to total demand. Finally, a novel data-driven algorithm for inferring unobserved demand from the data is proposed, and is applied to analyze how the relationship between demand and supply in a market with frictions compares to the frictionless equilibrium outcome.

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A Bayesian Comparison of Models of Network Formation                                           

Working Paper

Summary
Academic Abstract

A prominent feature of real-world social networks is a high level of clustering. I review different approaches to modeling network formation and clustering and I apply Bayesian model selection to evaluate the models. Preliminary results confirm that models that treat links as pairwise independent do not generate the levels of clustering observed in the data. Models that include unobserved heterogeneity perform slightly better than models with only observable characteristics.

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