Research

Socially Embedded Knowledge Networks and the Making of Opinion Leaders: Evidence from Twitter (Job Market Paper)

Abstract: This paper focuses on knowledge markets exploring how network relationships between knowledge consumers impact the equilibrium number of opinion leaders. Both a theoretical model and empirical analysis show that there’ll be more opinion leaders in a knowledge market if the most active knowledge consumers occupy more central positions in a social network connecting consumers. The model formalizes the following story. Knowledge consumers are embedded in network relationships through which they influence each other on which opinion providers they pay attention to. If the most active (thus most capable to influence) knowledge consumers occupy more central network positions, consumer attention gravitates toward some opinion providers, and this turns more opinion providers into opinion leaders. The model inspires and is supported by empirical analysis using a Twitter network and associated tweets. First, unsupervised machine learning is used to define knowledge markets: topic modeling finds 45 topics in tweets, network community detection yields 4 nearly isolated Twitter sub-networks, and a knowledge market is then defined by a combination of one topic and one sub-network. Second, with each knowledge market being a unit of observation, we define variables and test our theoretical predictions. This is the first paper to formally define opinion leaders, knowledge markets, and consumer attention. While the existing literature emphasizes the role of opinion providers’ network positions on the making of opinion leaders, this work shows the network positions of active consumers matter because active consumers serve as a propagation machine.

Assessing External Validity

(with Sebstian Galiani), NBER working paper No. 26422

Abstract: In designing any causal study, steps must be taken to address both internal and external threats to its validity. Researchers tend to focus primarily on dealing with threats to internal validity. However, once they have conducted an internally valid analysis, that analysis yields an established set of findings for the specific case in question. As for the future usefulness of that result, however, what matters is its degree of external validity. In this paper we provide a formal, general exploration of the question of external validity and propose a simple and generally applicable method for evaluating the external validity of randomized controlled trials.

Presented at: Washington Area Development Economics Symposium, 2019

Development Spillover and Institutional Changes: A Trade Economy Political Perspective

working paper

Abstract: In this paper I theoretically argue that people weigh specialization gains against trade costs when they decide whether to specialize and trade or self-produce all goods by themselves. In my model, trade costs relate to institutional quality. Thus, more people participate in trade under better institutions. I also show that the better the institution of an economy's trade partner, the more prosperous the economy is, thanks to expanded trade. Moreover, when more people trade, more people would like to fight for a better institution and may induce institutional changes. Depending on fundarmentals, the institutional changes may or may not have economic impacts that induce further institutional changes via reform or conflicts. Better initial institutions or lower trade costs facilitate continuous institutional improvements; but with very high initial institutional quality, people may lose their incentive to protest. I provide historical evidence consistent with the theory.

Other Research

“Health, Education, Quantity-Quality Tradeoff, and Economic Growth,” work in progress

“De Facto Institutions and Domestic Trade Network: Evidence from China,” work in progress