Slow Expectation–Maximization Convergence in Low‐Noise Dynamic Factor Models
低噪声动态因子模型中 EM 算法的缓慢收敛
ABSTRACT This paper addresses the slow convergence of the expectation–maximization (EM) algorithm in the estimation of low‐noise dynamic factor models, commonly used in macroeconomic nowcasting and forecasting. We show analytically and in Monte Carlo simulations how the EM algorithm stagnates in a low‐noise environment, leading to inaccurate estimates of factor loadings and factor realizations. An adaptive version of EM considerably speeds up convergence, producing…