Time-Varying Group Unobserved Heterogeneity in Finance
金融研究中的时变分组不可观测异质性
Accounting for time-varying unobserved heterogeneity poses a fundamental challenge for empirical finance research. We show how grouped fixed effects (GFE) models capture such heterogeneity and illustrate their merits over conventional panel data models used in finance applications. We propose a new Hausman-type specification test to select among fixed effects models, and show that it differs from standard Hausman statistics precisely due to the presence of the time-varying…