Associate Professor of Economics
Mailing address:
Virginia Commonwealth University
B3179 Snead Hall
301 W Main St
Richmond, VA 23284
E-mail:
yumm "at" vcu.edu
Links:
Department Website
Google Scholar Page
IDEAS/RePEc
ORCID
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We document significant gaps in wealth across health status over the life cycle in Germany---a country with a universal healthcare system and negligible out-of-pocket medical expenses. To investigate the underlying sources of these wealth-health gaps, we build a heterogeneous-agent life-cycle model in which health and wealth evolve endogenously. In the model, agents exert efforts to lead a healthy lifestyle, which helps maintain good health status in the future. Effort choices, or lifestyle behaviors, are subject to adjustment costs to capture their habitual nature in the data. We find that our estimated model generates the great majority of the empirical wealth gaps by health and quantify the role of earnings and savings channels through which health affects these gaps. We show that variations in individual health efforts account for around a quarter of the model-generated wealth gaps by health, illustrating their role as an amplification mechanism behind the gaps. |
DOI: https://doi.org/10.3982/ECTA20603 |
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East Asians, especially South Koreans, appear to be preoccupied with their offspring's education---most children spend time in expensive private institutes and in cram schools in the evenings and on weekends. At the same time, South Korea currently has the lowest total fertility rate in the world. Motivated by novel empirical evidence on spillovers in private education spending, we propose a theory with status externalities and endogenous fertility that connects these two facts. Using a quantitative heterogeneous-agent model calibrated to Korea, we find that fertility would be 28% higher in the absence of the status externality and that childlessness in the poorest quintile would fall from five to less than one percent. We then explore the effects of various government policies. A pro-natal transfer or an education tax can increase fertility and reduce education spending, with heterogeneous effects across the income distribution. The policy mix that maximizes the current generation's welfare consists of an education tax of 22% and moderate pro-natal transfers. This would raise average fertility by about 11% and decrease education spending by 39%. Although this policy increases the welfare of the current generation, it may not do the same for future generations as it lowers their human capital. |
DOI: https://doi.org/10.1257/aer.20220583 |
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Recent studies highlight the adverse effects of school closures in terms of average lifetime income loss, cross-sectional inequality, and intergenerational mobility. We use a simple model of human capital formation to compare two policy instruments that can address these negative consequences: direct public provision, such as through an extension of school time, and the provision of private education subsidies. We demonstrate that the effects of these policies on inequality and mobility depend crucially on the degree of substitutability between private and public inputs in the production of human capital. |
DOI: https://doi.org/10.1016/j.econlet.2024.111517 |
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This paper quantitatively investigates the medium- and long-term macroeconomic and distributional consequences of school closures through intergenerational channels. The model economy is a dynastic overlapping generations general equilibrium model in which schools, in the form of public education investments, complement parental investments in producing children's human capital. We find that unexpected school closure shocks have long-lasting adverse effects on macroeconomic aggregates and reduce intergenerational mobility, especially among older children. Higher substitutability between public and private investments induces smaller damages in the aggregate economy and the affected children's lifetime income, while exacerbating negative impacts on intergenerational mobility and inequality. |
DOI: https://doi.org/10.1257/mac.20200442 |
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This paper provides an extension of the classical indivisible labor supply model where a large macro Frisch elasticity is reconciled with a small micro counterpart. Households take as given state-dependent hours per worker, shaped by a nonlinear mapping from hours worked to labor services and employment frictions, and make intertemporal labor supply decisions. In the standard indivisible labor supply model, aggregate fluctuations are independent of the individual preference parameter that governs the intensive margin elasticity. In my model, however, they are connected through the extensive margin whose elasticity is empirically reasonable and is shaped by the individual preference parameter. |
DOI: https://doi.org/10.1111/sjoe.12544 |
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This paper studies how tax-and-transfer progressivity influences aggregate fluctuations when interacting with household heterogeneity. Using a simple static model of the extensive margin labor supply, we analytically characterize how a degree of progressivity influences differential labor supply responses to aggregate conditions across heterogeneous households. We then build a quantitative dynamic general equilibrium model with both idiosyncratic and aggregate productivity shocks and show that it delivers moderately procyclical average labor productivity and a large cyclical volatility of aggregate hours relative to output. Our quantitative exercises suggest that progressivity at the bottom of the income distribution shaped by the phasing out of transfers is key for these findings. Finally, we provide suggestive empirical evidence on the heterogeneity of employment responses across the wage distribution. |
DOI: https://doi.org/10.3982/QE1568 |
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This paper constructs an overlapping generations general equilibrium model to explore the extent to which heterogeneity in time investment shapes intergenerational mobility of lifetime income. The calibrated model successfully accounts for untargeted distributional aspects of income mobility, which are captured in the income quintile transition matrix. Counterfactual exercises show that removing heterogeneity in parental time investment reduces intergenerational persistence by around 7-8% for early childhood but only marginally in later childhood. Since parental time and monetary investments are poor substitutes for human capital development in early childhood, parental time investment during this period serves as a mechanism that amplifies the transmission of the parents' economic status to their children. Policy experiments find that an asset-tested subsidy for parental monetary investments in early childhood can raise intergenerational mobility in a cost-effective way, though it reduces mobility substantially if given to parents with older school-aged children. |
DOI: https://doi.org/10.1111/iere.12602 |
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Long hours worked associated with higher hourly wages are common to many occupations, known as nonlinear occupations. Over the last four decades, both the share of workers in nonlinear occupations and their relative wage premium have been increasing. Females in particular have been facing rising experience premiums, especially in these types of occupations. We quantitatively explore how these changes have affected the female labor supply over time using a quantitative, dynamic general equilibrium model of occupational choice and labor supply at both the extensive and intensive margins. Our decomposition analysis finds that rising experience premiums are important in explaining the intensive margin of female labor supply, which has continued to increase even in the most recent period. Meanwhile, technical changes biased toward nonlinear occupations help to explain recent stagnating female employment rates. Finally, a counterfactual experiment suggests that, if the barrier aspects of nonlinearities had instead gradually vanished, female employment over this same time period would have been considerably higher at the expense of significantly lower labor supplies at the intensive margin. |
DOI: https://doi.org/10.1016/j.red.2021.07.004 |
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This study considers model selection criteria, such as the Akaike's Information Criterion (AIC), the corrected Akaike's Information Criterion (AICc), and the Bayesian Information Criterion (BIC), for panel data models with fixed effects. Applying these information criteria to fixed effects panel models is not a trivial matter due to the incidental parameter problem that might adversely affect their practical performance, especially when it comes to short panel data. Monte Carlo experiments suggest that the information criteria are quite successful in selecting the true model. In particular, the AICc and the AIC operate successfully unless a time dimension is extremely small. |
DOI: https://dx.doi.org/10.1080/13504851.2021.1962505 |
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A higher labor tax rate increases the equilibrium real interest rate and reduces the equilibrium wage in a heterogeneous-agent model with endogenous savings and indivisible labor supply decisions. I show that these general equilibrium (GE) adjustments, in particular of the real interest rate, reinforce the negative employment impact of higher labor taxes. However, the representative-agent version of the model, which generates similar aggregate employment responses to labor tax changes, implies that GE feedback is neutral. The cross-country panel data reveal that the negative association between labor tax rates and the extensive margin labor supply is significantly and robustly weaker in small open economies where the interest rate is less tightly linked to domestic circumstances. This empirical evidence supports the transmission mechanism of labor tax changes for employment in the heterogeneous-agent model. |
DOI: https://doi.org/10.1017/S1365100519000087 |
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In the United States, the employment rate is nearly flat across wealth quintiles with the exception of the first quintile. Correlations between wealth and employment are close to zero or moderately positive. However, incomplete markets models with a standard utility function counterfactually generate a strongly negative relationship between wealth and employment. Using a fairly standard incomplete markets model calibrated to match the distribution of wealth, I find that government transfers and capital income taxation increase the (non-targeted) correlations between wealth and employment substantially, bringing the model closer to the data. As the model's fit with the distribution of wealth and employment improves, I find that the precautionary motive of labor supply is mitigated, thereby raising aggregate labor supply elasticities substantially. |
DOI: https://doi.org/10.1016/j.red.2018.04.001 |
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South Korea has been struggling with both low fertility rates and low female hours worked for several decades. To address these persistent challenges, the government has recently proposed generous parental leave policies, including provisions specifically designed to encourage both parents to take leave. How effective are these policies in achieving their objectives in a society with strong social norms about women’s roles within households and segmented labor markets, where career-oriented jobs require high entry costs and long working hours? We assess these questions using a quantitative, heterogeneous-household life-cycle model in which couples jointly make decisions about careers, labor supply, savings, and child-related choices such as fertility, childcare, and parental leave take-up. The model is calibrated to recent Korean cohorts to replicate key patterns observed in the data. Our findings suggest that the recently implemented, more generous parental leave benefits can narrow gender gaps in labor supply while moderately increasing fertility by enabling more women outside the labor force to pursue both career and family. In particular, the policy option with a higher replacement rate and cap boosts fertility by encouraging more equitable parental involvement in childcare. |