Constrained Principal Components Estimation of Large Approximate Factor Models
Abstract
Principal components (PC) are fundamentally feasible for the estimation oflarge factor models because consistency can be achieved for any path of the panel
dimensions. The PC method is however inecient under cross-sectional dependence
with unknown structure. The approximate factor model of Chamberlain
and Rothschild [1983] imposes a bound on the amount of dependence in the error
term. This article proposes a constrained principal components (Cn-PC) estimator
that incorporates this restriction as external information in the PC analysis
of the data. This estimator is computationally tractable. It doesn't require estimating
large covariance matrices, and is obtained as PC of a regularized form
of the data covariance matrix. The paper develops a convergence rate for the
factor estimates and establishes asymptotic normality. In a Monte Carlo study,
we nd that the Cn-PC estimators have good small sample properties in terms
of estimation and forecasting performances when compared to the regular PC
and to the generalized PC method (Choi [2012]).