Yongsung Chang
Seoul National University · 経済学
研究室紹介
Professor Yongsung Chang's research lab specializes in macroeconomic dynamics, with a focus on heterogeneous agent models, incomplete capital markets, and the role of labor market frictions in business cycle fluctuations. The lab investigates how idiosyncratic productivity shocks, learning-by-doing, and indivisible labor supply generate aggregate labor supply elasticities and wedges that match real-world data. Key research directions include the microfoundations of aggregate labor supply, the propagation of technology shocks across industries, and the econometric evaluation of DSGE models using Bayesian methods. The lab emphasizes the integration of micro-level panel data with aggregate time series to improve model realism and policy relevance.
Research Overview
Research Output Trend
Figures are computed from collected data and may differ slightly.
Selected Papers
15At the aggregate level, the labor‐supply elasticity depends on the reservation‐wage distribution. We present a model economy where workforce heterogeneity stems from idiosyncratic productivity shocks. The model economy exhibits the cross‐sectional earnings and wealth distributions that are comparable to those in the micro data. We find that the aggregate labor‐supply elasticity of such an economy is around 1, greater than a typical micro estimate.
This paper suggests that skill accumulation through past work experience, or “learning-by-doing” (LBD), can provide an important propagation mechanism in a dynamic stochastic general-equilibrium model, as the current labor supply affects future productivity. Our econometric analysis uses a Bayesian approach to combine micro-level panel data with aggregate time series. Formal model evaluation shows that the introduction of the LBD mechanism improves the model's ability to fit the dynamics of aggr
We demonstrate that aggregate employment and consumption can increase without a corresponding movement in productivity in a model with heterogeneous agents where the only aggregate disturbance is a productivity shock. The interaction between incomplete capital markets and indivisible labor results in a low employment-productivity correlation and creates a time-varying wedge between the marginal rate of substitution (for commodity consumption and hours) and productivity. Our results caution again
We find that technology's effect on employment varies greatly across manufacturing industries. Some industries exhibit a temporary reduction in employment in response to a permanent increase in TFP, whereas many more industries exhibit an employment increase in response to a permanent TFP shock. This raises serious questions about existing work that finds a labor productivity shock has a strong negative effect on employment. There are tantalizing and interesting differences between TFP and labor
Takahashi (2014) has uncovered coding errors in our paper, Chang and Kim (2007)—henceforth, CK. We acknowledge and are embarrassed by these mistakes. We are grateful to Takahashi for uncovering them. While the correction decreases the volatility of the labor market wedge, we find that the main message of CK remains valid: the measured labor market wedge arises endogenously in an economy with incomplete capital markets and indivisible labor supply. For example, our model accounts for 18 percent o
The time series fit of dynamic stochastic general equilibrium (DSGE) models often suffers from restrictions on the long‐run dynamics that are at odds with the data. Using Bayesian methods we estimate a stochastic growth model in which hours worked are stationary and a modified version with permanent labor supply shocks. If firms can freely adjust labor inputs, the data support the latter specification. Once we introduce frictions in terms of labor adjustment costs, the overall time series fit im
Data from a heterogeneous-agents economy with incomplete asset markets and indivisible labor supply are simulated under various fiscal policy regimes and an approximating representative-agent model is estimated. Preference and technology parameter estimates of the representative-agent model are not invariant to policy changes and the bias in the representative-agent model’s policy predictions is large compared to predictive intervals that reflect parameter uncertainty. Since it is not always fea
We construct a family model of labor supply that features adjustment along both the intensive and extensive margin. Intensive margin adjsutment is restricted to two values: full-time work and part-time work. Using simulated data from the steady state of the calibrated model, we examine whether standard labor supply regressions can uncover the true value of the intertemporal elasticity of labor supply parameter. We find positive estimated elasticities that are larger for women and that are highly