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Bayesian Inference and Prediction of a Multiple-Change-Point Panel Model with Nonparametric Priors
Change point models using hierarchical priors share in the information of each regime when estimating the parameter values of a regime. Because of this sharing, hierarchical priors have been very successful when estimating the parameter values of short-lived regimes and predicting the out-of-sample behavior of the regime parameters. However, the hierarchical priors have been parametric. Their parametric nature leads to global shrinkage that biases the estimates of the parameter coefficient of extraordinary regimes toward the value of the average regime. To overcome this shrinkage, we model the hierarchical prior nonparametrically by letting the hyperparameter's prior?in other words, the hyperprior?be unknown and modeling it with a Dirichlet processes prior. To apply a nonparametric hierarchical prior to the probability of a break occurring, we extend the change point model to a multiple-change-point panel model. The hierarchical prior then shares in the cross-sectional information of the break processes to estimate the transition probabilities. We apply our multiple-change-point panel model to a longitudinal data set of actively managed, U.S. equity, mutual fund returns to measure fund performance and investigate the chances of a skilled fund being skilled in the future.
AUTHORS: Fisher, Mark; Jensen, Mark J.
Heterogeneity in the Dynamics of Disaggregate Unemployment
This paper explores the role that unobserved heterogeneity within an observed category plays in the dynamics of disaggregate unemployment and in the cross-sectional differences across individuals of the duration of unemployment spells. The distribution of unobserved heterogeneity is characterized as a mixture of two distributions with each mean and weight determined by the inflows and outflows of workers with unobserved types H and L, which are identified based on the nonlinear state-space model of Ahn and Hamilton (2016). I found that the contribution of each factor to the dynamics of disaggregate unemployment differs by observed category. The inflow of type L workers is the most important factor in the majority of demographic groups in the business-cycle frequency. I identify permanent job loss to be the observable characteristic most closely associated with the type L attribute. A simple model of heterogeneity based on two unobserved types can account for explain more than 50 percent of the cross-sectional dispersion in completed-duration spells after the Great Recession, while observed heterogeneity makes only a minor contribution.
AUTHORS: Ahn, Hie Joo
Heterogeneity and Unemployment Dynamics
This paper develops new estimates of flows into and out of unemployment that allow for unobserved heterogeneity across workers as well as direct effects of unemployment duration on unemployment-exit probabilities. Unlike any previous paper in this literature, we develop a complete dynamic statistical model that allows us to measure the contribution of different shocks to the short-run, medium-run, and long-run variance of unemployment as well as to specific historical episodes. We find that changes in the inflows of newly unemployed are the key driver of economic recessions and identify an increase in permanent job loss as the most important factor.
AUTHORS: Ahn, Hie Joo; Hamilton, James D.
Mortgage Loss Severities: What Keeps Them So High?
Mortgage loss-given-default (LGD) increased significantly when house prices plummeted and delinquencies rose during the financial crisis, but it has remained over 40 percent in recent years despite a strong housing recovery. Our results indicate that the sustained high LGDs post-crisis are due to a combination of an overhang of crisis-era foreclosures and prolonged foreclosure timelines, which have offset higher sales recoveries. Simulations show that cutting foreclosure timelines by one year would cause LGD to decrease by 5?8 percentage points, depending on the trade-off between lower liquidation expenses and lower sales recoveries. Using difference-in-differences tests, we also find that recent consumer protection programs have extended foreclosure timelines and increased loss severities in spite of their benefits of increasing loan modifications and enhancing consumer protections.
AUTHORS: An, Xudong; Cordell, Lawrence R.