Unravelling in Two-Sided Matching Markets and Similarity of Preferences

This paper investigates the causes and welfare consequences of unravelling in two-sided matching markets. It shows that similarity of preferences is an important factor driving unravelling. In particular, it shows that under the ex-post stable mechanism (the mechanism that the literature focuses on), unravelling is more likely to occur when participants have more similar preferences. It also shows that any Pareto-optimal mechanism must prevent unravelling, and that the ex-post stable mechanism is Pareto-optimal if and only if it prevents unravelling.two-sided matching, unravelling, similarity of preferences

Imperfect Competition in Two-sided Matching Markets

This paper considers a simple equilibrium model of an imperfectly competitive two-sided matching market. Firms and workers may have heterogeneous preferences over matches on the other side, and the model allows for both uniform and personalized wages or contracts. To make the model tractable, I use the Azevedo and Leshno (2013) framework, in which a finite number of firms is matched to a continuum of workers. In equilibrium, even if wages are exogenous and fixed, firms have incentives to strategically reduce their capacity, to increase the quality of their worker pool. The intensity of incentives to reduce capacity is given by a simple formula, analogous to the classic Cournot model, but depends on different moments of the distribution of preferences. I compare markets with uniform and personalized wages. For fixed quantities, markets with personalized wages always yield higher efficiency than markets with uniform wages, but may be less efficient if firms reduce capacity to avoid bidding too much for star workers

Preference diversity orderings

This paper surveys approaches to preference diversity measurement. Applying preference diversity axiomatics, a generalization of the Alcalde-Unzu and Vorsatz (2016) criterion, is developed. It is shown that all previously used indices violate this criterion. Two new indices (geometric mean based and leximaxbased)are developed that satisfy a new criterion. Leximax-based orders act as a polarization index and are compared with Can et al.’s (2015) polarization index. The paper concludes by formulating a new open question: the preference profile reconstruction conjecture

A Two-sided Matching System Design for Dynamic Labor Markets

This thesis designs an automatic two-sided matching system for dynamic labor markets with large scale of data. Such markets consist of a group of vacancies and applicants, a matching function, a set of events causing transitions of the state of the market. Due to the dynamic nature of the labor markets, matching systems based on the classical deferred acceptance algorithm are not sufficient for producing stable matching solutions. Therefore, the central theme of this thesis is to address the effectiveness and efficiency of generating matching results in dynamic large labor markets. The main contribution of this thesis consists of three dynamic matching algorithms and a agent-based matching system design. The dynamic matching algorithms are extensions of the classical deferred acceptance algorithm. The first algorithm generates a vacancyoptimal stable matching result without considering locking or break-up constrains. The second algorithm considers locking period constraints in the matching process and the third algorithm computes applicant-optimal stable matchings with the consideration of break-up penalties in dynamic environments. To verify the effectiveness and efficiency of the proposed matching algorithms, theoretical proofs and experimental results are presented as well. The results indicate that the designed system can be used as an efficient and effective tool for recruitment management in today’s dynamic and internet based labor markets to reduce administrative work load of human resource departments and produce stable job allocations. ii

The Effects of a Centralized Clearinghouse on Job Placement, Wages, and Hiring Practices

New gastroenterologists participated in a labor market clearinghouse (a "match") from 1986 through the late 1990's, after which the match was abandoned. This provides an opportunity to study the effects of a match, by observing the differences in the outcomes and organization of the market when a match was operating, and when it was not. After the GI match ended, the market unraveled. Contracts were signed earlier each year, at diffuse times, often with exploding offers. The market became less national, more local. This allows us to discern the effect of the clearinghouse: it coordinated the timing of the market, in a way that increased its thickness and scope. The clearinghouse does not seem to have had an effect on wages. As this became known among gastroenterologists, an opportunity arose to reorganize the market to once again use a centralized clearinghouse. However it proved necessary to adopt policies that would allow employers to safely delay hiring and coordinate on using the clearinghouse. The market for gastroenterologists provides a case study of market failures, the way a centralized clearinghouse can fix them, and the effects on market outcomes. In the conclusion we discuss aspects of the experience of the gastroenterology labor market that seem to generalize fairly widely.

Strategic Uncertainty and Unraveling in Matching Markets

We present a theoretical explanation of inefficient early matching in matching markets. Our explanation is based on strategic uncertainty and strategic unraveling. We identify a negative externality imposed on the rest of the market by agents who make early offers. As a consequence, an agent may make an early offer because she is concerned that others are making early offers. Yet other agents make early offers because they are concerned that others worry about early offers; and so on and so forth. The end result is that any given agent is more likely to make an early offer than a later offer

Strategic complementarities and unraveling in matching markets

We present a theoretical explanation of inefficient early matching in matching markets. Our explanation is based on strategic complementarities and strategic unraveling. We identify a negative externality imposed on the rest of the market by agents who make early offers. As a consequence, an agent may make an early offer because she is concerned that others are making early offers. Yet other agents make early offers because they are concerned that others worry about early offers, and so on and so forth. The end result is that any given agent is more likely to make an early offer than a late offer

Self-Confidence and Unraveling In Matching Markets

We document experimentally how biased self-assessments affect the outcome of matching markets. In the experiments, we exogenously manipulate the self-confidence of participants regarding their relative performance by employing hard and easy real-effort tasks. We give participants the option to accept early offers when information about their performance has not been revealed, or to wait for the assortative matching based on their actual relative performance. Early offers are accepted more often when the task is hard than when it is easy. We show that the treatment effect works through a shift in beliefs, i.e., underconfident agents are more likely to accept early offers than overconfident agents. The experiment identifies a behavioral determinant of unraveling, namely biased self-assessments, which can lead to penalties for underconfident individuals as well as efficiency losses