Thursday, June 11, 2009


Many markets have trouble coordinating on the timing of transactions, and this has led to market failures in markets as diverse as the market for college football bowls, and the labor market for federal court clerks, and in various medical markets, such as (most recently) gastroenterologists and orthopaedic surgeons.

Why do transactions in some markets happen inefficiently early? Here are the concluding paragraphs from our recent NBER working paper Unraveling Results from Comparable Demand and Supply: An Experimental Investigation
by Muriel Niederle, Alvin E. Roth, M. Utku Unver - #15006 (LS)

" It has been known at least since Roth and Xing (1994) that many markets unravel, so that offers become progressively earlier as participants seek to make strategic use of the timing of transactions. It is clear that unraveling can have many causes, because markets are highly multidimensional and time is only one dimensional (and so transactions can only move in two directions in time, earlier or later). So there can be many different reasons that make it advantageous to make transactions earlier. There can also be strategic reasons to delay transactions; see e.g. Roth and Ockenfels (2002) on late bidding in internet auctions.
Thus the study of factors that promote unraveling is a large one, and a number of distinct causes have been identified in different markets or in theory, including instability of late outcomes (which gives blocking pairs an incentive to identify each other early), congestion of late markets (which makes it difficult to make transactions if they are left until too late), and the desire to mutually insure against late-resolving uncertainty. There has also been some study of market practices that may facilitate or impede the making of early offers, such as the rules and customs surrounding "exploding" offers, which expire if not accepted immediately.
In this paper we take a somewhat different tack, and consider conditions related to supply and demand that will tend to work against unraveling, or to facilitate it. There seems to be a widespread perception, in markets that have experienced it, that unraveling is sparked by a shortage of workers.
But for inefficient unraveling to occur, firms have to be willing to make early offers and workers have to be willing to accept them. Our experiment supports the hypothesis that a shortage of workers is not itself conducive to unraveling, since workers who know that they are in short supply need not hurry to accept offers by lower quality firms. Instead, in the model and in the experiment, it is comparable supply and demand that leads to unraveling, in which attention must be paid not only to the overall demand and supply, but to the supply and demand of workers and firms of the highest quality. This seems to reflect what we see in many unraveled markets, in which competition for the elite firms and workers is fierce, but the quality of workers may not be reliably revealed until after a good deal of hiring has already been completed."

Postscript: Skip Sauer over at The Sports Economist has a post about a 9th grader offered a college football scholarship in what is becoming a seriously unraveled market.

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