New Double Auction Paper

This weekend I am at the Economic Science Association meeting.

Most of the economists in this group use experiments as part of their empirical research. In this post I will highlight some recently published work that is in the tradition of Vernon Smith, who influenced all of us so much.

Martinelli, C., Wang, J. & Zheng, W. Competition with indivisibilities and few traders. Experimental Economics (2022).

Abstract: We study minimal conditions for competitive behavior with few agents. We adapt a price-quantity strategic market game to the indivisible commodity environment commonly used in double auction experiments, and show that all Nash equilibrium outcomes with active trading are competitive if and only if there are at least two buyers and two sellers willing to trade at every competitive price. Unlike previous formulations, this condition can be verified directly by checking the set of competitive equilibria. In laboratory experiments, the condition we provide turns out to be enough to induce competitive results, and the Nash equilibrium appears to be a good approximation for market outcomes. Subjects, although possessing limited information, are able to act as if complete information were available in the market.

This small excerpt from their results shows a market converging toward equilibrium over time, under different treatment conditions. With some opportunities for practice and feedback, agents create surplus value by trading.

Figure 4 plots the average efficiency in each round in the four treatments. Efficiency is defined as the percentage of the maximum social surplus realized. … learning takes longer under the clearing house institution; hence, average efficiency under the clearing house institution presents a stronger upward trend over time. Under the clearing house institution, the average efficiencies start at levels lower than under the double auction institution, and remain statistically lower in the second half of the experiment. Nevertheless, we can observe from Fig. 4 that the upward trend of the efficiencies in clearing house treatments persist over time, and at the end of the experiment, the efficiency levels from the two institutions are close.

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