Ming Xu
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Working papers

Heterogeneous Passthrough from TFP to Wages 
with Mons Chan and Sergio Salgado

We examine the transmission of firms' idiosyncratic productivity shocks to workers' wages using matched employer-employee data from Denmark. Our novel method controls for productivity differences across firms due to unobserved differences in labor quality and for workers' endogenous job mobility decisions. We find an average elasticity of workers' hourly wages to firms' productivity of 0.08. This implies that a productivity shock of one standard deviation generates a change of $1,100 US dollars in annual wages for the average worker in Denmark. The passthrough of firm shocks to wages is strongly asymmetric, in that workers' wages are twice as responsive to negative shocks as positive shocks. Failing to control for endogenous worker mobility dramatically underestimates the passthrough of negative shocks and reverses the direction of asymmetry. Our results also indicate significant heterogeneity across firm and worker characteristics. We show that a simple model where firms with labor market power interact strategically can rationalize our findings. Through the lens of this model, our estimates imply an average firm-level labor supply elasticity of 5.7 and average wage markdowns of 15%

Understanding the Decline in Occupational Mobility [New draft coming soon]

The process of workers switching from occupation to occupation is a vital part of career development and self-discovery. Using the CPS and SIPP, I show that occupational switching rates have declined significantly over the past 25 years. This decline has been robust for each consecutive cohort and is more pronounced for younger workers than older workers. The decline could imply that it is becoming more difficult and costly for workers to find better jobs (due to increases in switching costs), leaving people increasingly stuck in poorly matched and unfulfilling careers. Paradoxically, it could also mean that finding better jobs is becoming easier (thanks to advances in ICT), since workers with good job matches are less likely to switch. This paper develops a dynamic discrete choice life-cycle model to separately identify and quantify how changes in switching costs and information over time contribute to the observed declines in occupation switching. The result is that increased switching costs drive about 72% of the decline, while better information drives about 8%. The increases in switching costs have led to less productive occupational matches for workers and thus significant welfare losses. On average, workers have lost 3% of their total lifetime income from increases in switching costs over this period.
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Firm Productivity and Labor Quality  [Draft coming soon] 
with Mons Chan and Sergio Salgado

In this paper we argue that a large fraction of the observed dispersion in firm productivity can be accounted for by differences in labor quality. In order to investigate this claim, we propose an estimation method that combines a non parametric production function estimation with a series of two-way fixed effect wage regressions with time-varying firm fixed effects which allow us to control for differences in labor quality across firms and time. We implement this method on a large employer-employee matched panel dataset from Denmark and find that around 60% of the dispersion in productivity can be explained by cross-sectional differences in the quality of labor. A similar fraction of the dispersion in idiosyncratic shocks to firm productivity can be attributed to changes in the quality of the labor force hired by the firm. Using these labor quality-adjusted measures of productivity, we find a significant degree of positive assortative matching between high ability workers and high productivity firms. High productivity firms also tend to pay higher wages per unit of ability than low productivity firms. We also find that firms react to productivity shocks by adjusting both the quantity and quality of their labor force. We then discuss the degree to which cross-sectional wage inequality may be driven by dispersion in firm productivity.


Occupational Licensing and Labor Market Fluidity  
​with Morris Kleiner

We show that occupational licensing has significant negative effects on labor market fluidity defined as cross-occupation mobility. Using a balanced panel of workers constructed from the CPS and SIPP data, we analyze the link between occupational licensing and labor market outcomes. We find that workers with a government-issued occupational license experience churn rates significantly lower than those of non-licensed workers. Specifically, licensed workers are 24% less likely to switch occupations and 3\% less likely to become unemployed in the following year. Moreover, occupational licensing represents barriers to entry for both non-employed workers and employed ones. The effect is more prominent for employed workers relative to those entering from non-employment, because the opportunity cost of acquiring a license is much higher for employed individuals. Lastly, we find that average wage growth is higher for licensed workers than non-licensed workers, whether they stay in the same occupation in the next year or switch occupations. We find significant heterogeneity in the licensing effect across different occupation groups. These results hold across various data sources, time spans, and indicators of being licensed. Overall, licensing could account for almost 8% of the total decline in monthly occupational mobility over the past two decades.

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Works in Progress

Trade, Occupation Sorting, and Inequality [Draft available upon request] 
with Mons Chan

Firms react to changes in factor prices with intensive and extensive-margin employment adjustments at the occupational-level. We study the distributional and aggregate consequences of this make-or-buy dynamic by developing a novel network model of heterogeneous firm-to-firm trade where the boundary of each firm depends on factor prices and firm-occupation comparative advantage in input-production. We show that the model can be easily aggregated and taken to industry-level data, and use the calibrated model to examine recent trends in employment, wages and trade in the USA. We use public OES and CPS data to show empirical evidence that a significant fraction of the growth in wage inequality in the USA is due to changes in firm/industry specialization and occupation sorting. To understand and measure the underlying causes of these trends, we calibrate the model to occupation and industry data from the OES and input-output tables. The results suggest that 1/3rd of the increases in wage inequality stem from decreases in inter-industry trade frictions with the remaining 2/3rds stemming from changes in technology and labor supply. Falling trade frictions are also responsible for all of the increases in occupational sorting and concentration. Had trade frictions been held at their 2002 level, productivity growth would have led to an increase in vertical integration, rather than the decrease observed in the data.


Student Loans and Early Employment Outcomes  [Draft available upon request] 
​with Emily Moschini

In this paper I investigate the link between student debt and post-graduation job market outcomes.  Using a combination of survey and administrative data on graduates in two cohorts, I show that there is a significant negative correlation between the amount of debt upon graduation and the probability of finding a job which matches your education. I use evidence from Equifax to motivate a model of job search and long-term debt where the cost of consumer credit depends on your student loan balance. I successfully calibrate the model to the data and show that this debt constraint mainly binds for high and medium human capital graduates, as it affects the amount of time they are able to spend searching for a good job. I then show that alternative repayment and interest rate policies would have improved labor market outcomes for graduates in 07/08 by allowing extended search times, increasing match quality and possibly lifetime productivity.

MPC Heterogeneity and Firm Level Shocks
with Mons Chan, Sergio Salgado and Bastian Schulz


Occupational Concentration and Re-employment Risk
with Bent Jesper Christensen and Similan Rujiwattanapong 


Understanding Worker Flows across Heterogeneous Firms
with Bastian Schulz
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