Research Statement

I am an economist, interested in how groups of agents form, and the incentives that guide a group's operation. I have studied these topics from both macroeconomic and microeconomic perspectives, using both theoretical and empirical methods. On the macro side, I consider countries in a convergence group who come together in a coalition such as the IMF to prevent sovereign default inside their ranks. By observing the behavior of this coalition, I can parse out the spillovers caused by defaults, from the correlated shocks in the convergence group. This work led me to think about how such groups form, and how their membership evolves over time.

Therefore, in my job market paper, I went on to study a dynamic game in which members of a group vote on new inductions and prefer to induct applicants of their own type. These members know that newly inducted members will have a say in future elections so their own-type preferences are attenuated. I call this incentive which arises "Dynamic Homophily", and I characterize it theoretically and quantify it empirically. Empirically, I apply this model to the decisions of tenured faculty in an economics department who vote to hire a new candidate with tenure. To do so, I use a novel dataset on 40 top US economics departments over 24 years. This dataset includes the positions, citation counts, and JEL codes of the department members. I find significant evidence that own-type preference is strong in this environment. In addition, the role of the new hire in future elections factors strongly in decision making.

I believe this model is very versatile, and look forward to applying it to a range of other environments such as state formation (induction of states into the US), the formation of military alliances networks (NATO), or trade groups (the EU) and monetary unions (the EMU), and the expansion of suffrage. In all these cases, agents have reason to prefer their own type, and they vote together with newly inducted members in future elections. On another track, I hope to use the data set I collected for future empirical work in studying academia, and the field of economics.

I hypothesize in my job market paper that department members care about a researcher's quality, and the research synergies that can be realized by having him aboard. I hope that the quality of my research shows in its rigor and creativity, and that I can join your department to be a helpful and productive colleague.

Research Statement [Download]

Job Market Paper

Search By Committee for new Voting Members: A Study of Tenured Hiring in Economics. [Download]

I examine a dynamic model of search by committee in which homophilic committee members vote to induct a candidate after observing the candidate's type and quality. A newly hired candidate joins the committee and votes in future elections. I study a new form of homophily that arises in this environment due to committee members' considerations of future elections, and call this "Dynamic Homophily". Dynamic Homophily is characterized across variables such as committee size and composition, and the separation rate. I then estimate this model using a novel data set on the faculty of top public Economics departments in the US from 1994 to 2017. Researchers are clustered into types using JEL codes found in their publication histories, and their quality is measured using their citation counts. Estimation results suggest that to set a committee member indifferent between a same-type and a cross-type applicant, the cross-type applicant must have 80% more citations than the same-type applicant. Dynamic Homophily is responsible for up to an additional 20\% of the difference between same- and cross-type reservation values. In counterfactual experiments, I find that for high values of homophily, agents prefer a dictator, even of the other type, rather than voting, as the dictator solves the externality caused by Dynamic Homophily.

Other Research Papers

Birds of a Feather: Disentangling Spillovers and Shocks in Cooperative Convergence Groups.

In this paper, I propose a tractable model of sovereign default and the inter-state spillovers emanating from default. A coalition of nations may choose to insure against default, and the behavior of the coalition is used to examine the magnitude of the international spillovers. A voting structure for the coalition is proposed to examine idiosyncratic spillovers. Finally, the model is calibrated to the recent Greek Debt crisis to understand the spillovers from a default, and the moral hazard effect of the Troika.

Contact Info

Ryan RudderhamDepartment of EconomicsS252 Pappajohn Business Building,The University of Iowa,Iowa City, IA 52242, United States.
(+1) 727-432-0021