Tuesday, March 17, 2009

Patents Versus Markets: a Market Design Experiment

The March 16 issue of Science contains a laboratory experiment concerned with a market design question (subscription required): Promoting Intellectual Discovery: Patents Versus Markets by Debrah Meloso, Jernej Copic, and Peter Bossaerts.

(Science is one of those journals with a pre-publication news embargo designed to promote press coverage; here is the corresponding Cal Tech press release (HT to Alex Tabarrok at MR).

While a lot of market design work is prompted by very specific markets, this paper deals with a more abstract question: could a market system without patents do as well as a patent system in encouraging innovation, if innovators could use their private information to make investments that would have unusually high returns?

Here is the abstract:
"Because they provide exclusive property rights, patents are generally considered to be an effective way to promote intellectual discovery. Here, we propose a different compensation scheme, in which everyone holds shares in the components of potential discoveries and can trade those
shares in an anonymous market. In it, incentives to invent are indirect, through changes in share prices. In a series of experiments, we used the knapsack problem (in which participants have to determine the most valuable subset of objects that can fit in a knapsack of fixed volume) as a
typical representation of intellectual discovery problems. We found that our “markets system” performed better than the patent system."

The key experimental treatment is described thus:
"In the markets system, participants were given an equal number of shares in each of the items of the particular KP, as well as cash. They could trade these shares in an anonymous, electronic exchange platform during a preset amount of time (840 s). The allowed time was double that of the prize system to compensate for the fact that subjects needed to perform two tasks: to solve the KP and to trade (to exploit the knowledge they gained from solving the KP). The platform was organized as a continuous double-sided open book (Fig. 1B), like most purely electronic stock markets in the world. The accumulation of orders generated the first transactions after about 100 s. Thereafter, trading remained brisk in virtually all markets (Fig. 1C). After markets closed, each share in an item that was in the optimal solution paid a liquidating dividend of $1; shares corresponding to items not in the optimal solution expired worthless."

The main results:
"The correct solution was found under the markets system whenever this was the case under the prize system. Therefore, if the concern is to design a system that produces the optimal solution, the markets and prize systems are equivalent. In one important respect, however, the markets system outperformed: Significantly more participants reported the correct solution than under the prize system (Fig. 2A). For both systems, the fraction of participants who reported the correct solution declined with problem difficulty (Fig. 2B). The fraction may seem to decline faster for the markets treatment, but the difference in slopes was not significant. An outlier influenced the fits: Nobody ever solved the most difficult problem (difficulty = 6). It was solved in follow-up experiments [ran to check for robustness (11)], but only with the markets system, further corroborating its superiority.
"In the prize system, only the first to find the optimal solution is compensated, which may discourage many from spending effort. In the markets system, everyone could be compensated in principle, which may be sufficient to explain why more participants find the optimal solution. Alternatively, prices may convey information that facilitates problem solving for participants who would never find the optimal knapsack on their own. Figure 3A shows that prices indeed do provide a potential channel of communication: Prices of shares of items that were part of the optimal knapsack (“in” items) tended to be higher than shares of items that were not part of it (“out” items); the mean transaction price of in items was significantly higher than that of out items (P < 0.01)."

HT Joshua Gans of Core Economics

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