Hans-Theo Normann

A Comparative Statics Analysis of Punishment in Public-Good Experiments

This paper provides a comparative statics analysis of punishment in public-good experiments. We vary systematically the effectiveness of punishment, that is, the factor by which punishment reduces the punished players income, and we find that contributions to the public good increase monotonically in effectiveness. High effectiveness leads to near complete contribution rates and welfare improvements. Below a certain threshold, however, punishment cannot prevent the decay of cooperation found in the public-good game without punishment. In these cases, the possibility to punish may even worsen welfare. Finally, we show that punishment is a normal and inferior good.

Learning in Cournot Oligopoly: An Experiment

This experiment was designed to test various learning theories in the context of a Cournot oligopoly. We derive theoretical predictions for the learning theories and test these predictions by varying the information given to subjects. The results show that some subjects imitate successful behavior if they have the necessary information; and if they imitate, markets are more competitive. Other subjects follow a best reply process. On the aggregate level we find that more information about demand and cost conditions yields less competitive behavior, while more information about the quantities and profits of other firms yields more competitive behavior.

The impact of the termination rule on cooperation in a prisoner’s dilemma experiment

Cooperation in prisoners dilemma games can usually be sustained only if the game has an infinite horizon. We analyze to what extent the theoretically crucial distinction of finite vs. infinite-horizon games is reflected in the outcomes of a prisoners dilemma experiment. We compare three different experimental termination rules in four treatments: a known finite end, an unknown end, and two variants with a random termination rule (with a high and with a low continuation probability, where cooperation can occur in a subgame-perfect equilibrium only with the high probability). We find that the termination rules do not significantly affect average cooperation rates. Specifically, employing a random termination rule does not cause significantly more cooperation compared to a known finite horizon, and the continuation probability does not significantly affect average cooperation rates either. However, the termination rules may influence cooperation over time and end-game behavior. Further, the (expected) length of the game significantly increases cooperation rates. The results suggest that subjects may need at least some learning opportunities (like repetitions of the supergame) before significant backward induction arguments in finitely repeated game have force.

STACKELBERG BEATS COURNOT: ON COLLUSION AND EFFICIENCY IN EXPERIMENTAL MARKETS*

We report on an experiment designed to compare Stackelberg and Cournot duopoly markets with quantity competition. We implement both a random matching and a fixed-pairs version for each market. Stackelberg markets yield, regardless of the matching scheme, higher outputs than Cournot markets and, thus, higher efficiency. For Cournot markets, we replicate a pattern known from previous experiments. There is stable equilibrium play under random matching and partial collusion under fixed pairs. We also find, for Stackelberg markets, that competition becomes less intense when firms remain in pairs but we find considerable deviations from the subgame perfect equilibrium prediction which can be attributed to an aversion to disadvantageous inequality.

Excess Capacity and Pricing in Bertrand-Edgeworth Markets: Experimental Evidence

We conduct experiments testing the relationship between excess capacity and pricing in repeated Bertrand-Edgeworth duopolies and triopolies. We systematically vary the experimental markets between low excess capacity (suggesting monopoly) and no capacity constraints (suggesting perfect competition). Controlling for the number of firms, higher production capacity leads to lower prices. However, the decline in prices as industry capacity rises is less pronounced than predicted by Nash equilibrium, and a model of myopic price adjustments has greater predictive power. With higher capacities, Edgeworth-cycle behavior becomes less pronounced, causing lower prices. Evidence for tacit collusion is limited and restricted to low-capacity duopolies.

Do short-term laboratory experiments provide valid descriptions of long-term economic interactions? A study of Cournot markets

One key problem regarding the external validity of laboratory experiments is their duration: while economic interactions out in the field are often lengthy processes, typical lab experiments only last for an hour or two. To address this problem for the case of both symmetric and asymmetric Cournot duopoly, we conduct internet treatments lasting more than a month. Subjects make the same number of decisions as in the short-term counterparts, but they decide once a day. We compare these treatments to corresponding standard laboratory treatments and also to short-term internet treatments lasting one hour. We do not observe differences in behavior between the short- and long-term in the symmetric treatments, and only a small difference in the asymmetric treatments. We overall conclude that behavior is not considerably different between the short- and long-term.

Simultaneous and Sequential Contributions to Step-Level Public Goods: One vs. Two Provision Levels

In a step-level public-good experiment, we investigate how the order of moves (si- multaneous vs. sequential) and the number of step levels (one vs. two) aects public-good provision in a two-player game. WeWe analyze the provision of a step-level public good in an experiment. Specifically, we investigate how the order of moves and the introduction of a second step-level affects public-good provision. We find that the sequential-move game improves public-good provision and payoffs. An additional step-level does lead to higher contributions but the effect on public-good provision is ambiguous and insignificant. Based on an existing data set, we calibrate Fehr and Schmidts (1999) model of inequality aversion and find that actual behavior fits remarkably well with these predictions in a quantitative sense, but there are also two contradictions to the models predictions.

Simultaneous and Sequential Contributions to Step-level Public Goods

In a step-level public-good experiment, we investigate how the order of moves (simultaneous vs. sequential) and the number of step levels (one vs. two) affects public-good provision in a two-player game. We find that the sequential order of moves significantly improves public-good provision and payoffs, even though second movers often punish first movers who give less than half of the threshold contribution. The additional second step level—which is not feasible in standard Nash equilibrium—leads to higher contributions but does not improve public-good provision and lowers payoffs. We calibrate the parameters of Fehr and Schmidt’s model of inequality aversion to make quantitative predictions. We find that actual behavior fits remarkably well with several predictions in a quantitative sense.

To Commit or Not to Commit: Endogenous Timing in Experimental Duopoly Markets

In this paper, we experimentally investigate the extended game with action commitment of Hamilton and Slutsky (1990). In their duopoly game, firms can choose their quantities in one of two periods before the market clears. If a firm commits to a quantity in period 1 it does not know whether the other firm also commits early. By waiting until period 2, a firm can observe the other firms period 1 action. Hamilton and Slutsky predict the emergence of endogenous Stackelberg leadership. Our data, however, does not confirm the theory. While Stackelberg equilibria are extremely rare we often observe endogenous Cournot outcomes and sometimes collusive play. This is partly driven by the fact that endogenous Stackelberg followers learn to behave in a reciprocal fashion over time, i.e., they learn to reward cooperation and to punish exploitation.(This abstract was borrowed from another version of this item.)

The willingness to sell personal data

We elicit the willingness to sell personal data (contact information, Facebook details, preferences) in laboratory experiments, using a BDM and take-it-or-leave-it offers. Our experiments are novel in that (i) the experiments are incentivized, (ii) the focus on privacy issues is salient, and (iii) the use of the data - marketing purposes - is transparent and unambiguous. We find that only a minority of about 10% to 20% of the participants are unwilling to sell personal data, a share which is roughly constant across both the type of personal data and elicitation method. Subjects willing to sell request about € 15 for their contact details and € 19 for Facebook details.