Essays on Macroeconomic Analysis of Geographical Reallocation

This dissertation consists of two essays that study the determinants of geographical reallocation and their macroeconomic implications. In the first chapter (co-authored with Y. Fatih Karahan), we study the role of the aging population in the long-run decline of interstate migration in the United States. We argue that, in addition to a direct compositional effect on migration, the aging population has an indirect general equilibrium effect through the labor market. There is a positive composition externality of high-moving-cost workers on the local labor market: An increase in the fraction of high-moving-cost workers increases the local job-finding rate and reduces the migration rate of all workers. We label this effect as migration spillovers. Our quantitative analysis suggests that population aging decreases the annual interstate migration rate by 0.9 percentage points, which accounts for 59 percent of the observed decline. Of this 0.9 percentage points, 78 percent is attributable to the indirect general equilibrium effect of the aging population and only 22 percent is due to the direct effect. In the second chapter (co-authored with Y. Fatih Karahan), we construct an equilibrium model of multiple locations with frictional housing and labor markets to study the effect of the housing bust on labor reallocation. The minimum down payment requirement makes it harder for homeowners to trade houses when house prices decrease. Consequently, the housing bust reduces migration and increases the unemployment dispersion. The model accounts for 90 percent of the increase in dispersion of unemployment and the entire decline in net migration. However, the effect on aggregate unemployment is moderate: absent the housing bust, aggregate unemployment would have been 0.5 percentage points lower

Formation and Evolution of Planetary Systems (FEPS): Properties of Debris Dust around Solar-type Stars

We present Spitzer photometric (IRAC and MIPS) and spectroscopic (IRS low resolution) observations for 314 stars in the Formation and Evolution of Planetary Systems (FEPS) Legacy program. These data are used to investigate the properties and evolution of circumstellar dust around solar-type stars spanning ages from approximately 3 Myr to 3 Gyr. We identify 46 sources that exhibit excess infrared emission above the stellar photosphere at 24um, and 21 sources with excesses at 70um. Five sources with an infrared excess have characteristics of optically thick primordial disks, while the remaining sources have properties akin to debris systems. The fraction of systems exhibiting a 24um excess greater than 10.2% above the photosphere is 15% for ages < 300 Myr and declines to 2.7% for older ages. The upper envelope to the 70um fractional luminosity appears to decline over a similar age range. The characteristic temperature of the debris inferred from the IRS spectra range between 60 and 180 K, with evidence for the presence of cooler dust to account for the strength of the 70um excess emission. No strong correlation is found between dust temperature and stellar age. Comparison of the observational data with disk models containing a power-law distribution of silicate grains suggest that the typical inner disk radius is > 10 AU. Although the interpretation is not unique, the lack of excess emission shortwards of 16um and the relatively flat distribution of the 24um excess for ages <300~Myr is consistent with steady-state collisional models.Comment: 85 pages, 18 figures, 4 tables; accepted for publication in ApJ

ERS: A simple scoring system to predict early recurrence after surgical resection for hepatocellular carcinoma.

peer reviewed[en] BACKGROUND: Surgical resection (SR) is a potentially curative treatment of hepatocellular carcinoma (HCC) hampered by high rates of recurrence. New drugs are tested in the adjuvant setting, but standardised risk stratification tools of HCC recurrence are lacking. OBJECTIVES: To develop and validate a simple scoring system to predict 2-year recurrence after SR for HCC. METHODS: 2359 treatment-naïve patients who underwent SR for HCC in 17 centres in Europe and Asia between 2004 and 2017 were divided into a development (DS; n = 1558) and validation set (VS; n = 801) by random sampling of participating centres. The Early Recurrence Score (ERS) was generated using variables associated with 2-year recurrence in the DS and validated in the VS. RESULTS: Variables associated with 2-year recurrence in the DS were (with associated points) alpha-fetoprotein (100: 3), size of largest nodule (≥40 mm: 1), multifocality (yes: 2), satellite nodules (yes: 2), vascular invasion (yes: 1) and surgical margin (positive R1: 2). The sum of points provided a score ranging from 0 to 11, allowing stratification into four levels of 2-year recurrence risk (Wolbers' C-indices 66.8% DS and 68.4% VS), with excellent calibration according to risk categories. Wolber's and Harrell's C-indices apparent values were systematically higher for ERS when compared to Early Recurrence After Surgery for Liver tumour post-operative model to predict time to early recurrence or recurrence-free survival. CONCLUSIONS: ERS is a user-friendly staging system identifying four levels of early recurrence risk after SR and a robust tool to design personalised surveillance strategies and adjuvant therapy trials

Disability and Occupational Labor Transitions: Evidence from South Korea

We examine how certain occupational physical requirements affect labor transitions of disabled workers by exploiting a unique feature of South Korean Disability Insurance (DI), where award rules are based solely on an applicant’s medical condition, independent of his previous occupations. We estimate the labor market response to a health shock by constructing a physical intensity measure from O*NET and applying it to longitudinal South Korean household panel data. Our results suggest that health shocks initially lead to a 14 to 20 percent drop in employment and that this effect is greater for workers who previously held physically demanding occupations. Those who remain part of the labor market exhibit higher occupational mobility toward less physically demanding jobs. These findings imply that the magnitudes of income risks associated with health shocks vary depending on occupational and skill characteristics

The Role of the Housing Bust

This paper presents preliminary findings and is being distributed to economists and other interested readers solely to stimulate discussion and elicit comments. The views expressed in this paper are those of the authors and are not necessarily reflective of views at the Federal Reserve Bank of New York or the Federal Reserve System. Any errors or omissions are the responsibility of the authors. Geographical Reallocation and Unemployment during the Great Recession