This paper shows theoretically and experimentally that hearing expert opinions can be a double-edged sword for collective decision making. We present a majoritarian voting game of common interest where committee members receive not only private information, but also expert information that is more accurate than private information and observed by all members. In theory, there are Bayesian Nash equilibria where the committee members’ voting strategy incorporates both types of information and access to expert information enhances the efficiency of the majority decision. However, there is also a class of potentially inefficient equilibria where a supermajority always follow expert information and the majority decision does not aggregate private information. In the laboratory, the majority decisions and the subjects’ voting behaviour were largely consistent with those in the class of inefficient equilibria. We found a large efficiency loss due to the presence of expert information especially when the committee size was large. We suggest that it may be desirable for expert information to be revealed only to a subset of committee members.
|Keywords:||committee decision making, voting experiment, expert information, strategic voting|
|JEL:||C92 D72 D82|
We report a controlled laboratory experiment examining risk-taking and information aggregation in groups facing a common risk. The experiment allows us to examine how subjects respond to new information, in the form of both privately observed signals and signals reported from others. We find that a considerable number of subjects exhibit ‘reverse confirmation bias’: they place less weight on information from others that agrees with their private signal and more weight on conflicting information. We also find a striking degree of consensus when subjects make decisions on behalf of the group under a random dictatorship procedure. Reverse confirmation bias and the incidence of consensus are considerably reduced when group members can share signals but not communicate.
|Keywords:||Group behaviour; teams; decision making; risk; experiment|
|JEL:||C91 C92 D71 D80|
|By:||Tor Eriksson (Department of economics – University of Aarhus)
Lei Mao (GATE Lyon Saint-Étienne – Groupe d’analyse et de théorie économique – ENS Lyon – École normale supérieure – Lyon – UL2 – Université Lumière – Lyon 2 – UCBL – Université Claude Bernard Lyon 1 – Université Jean Monnet – Saint-Etienne – PRES Université de Lyon – CNRS, Central University of Finance and Economics)
Marie Claire Villeval (GATE Lyon Saint-Étienne – Groupe d’analyse et de théorie économique – ENS Lyon – École normale supérieure – Lyon – UL2 – Université Lumière – Lyon 2 – UCBL – Université Claude Bernard Lyon 1 – Université Jean Monnet – Saint-Etienne – PRES Université de Lyon – CNRS)
Are people willing to sacrifice resources to save one’s and others’ face? In a laboratory experiment, we study whether individuals forego resources to avoid the public exposure of the least performer in their group. We show that a majority of individuals are willing to pay to preserve not only their self-but also other group members’ image. This behavior is frequent even in the absence of group identity. When group identity is more salient, individuals help regardless of whether the least performer is an in-group or an out-group. This suggests that saving others’ face is a strong social norm.
==notes by yinung==
self-image concerns: 可看見別人的決策, 但別人看不到自己的決策
social-image concerns: 自己的決策可以被看見
自我傾向者, 隨團隊走 (若貢獻<平均, 則增加貢獻), 而且此種人, 貢獻較穩定
|By:||Martin Daniel Siyaranamual (Department of Economics, Padjadjaran University)|
Social interactions may encourage the cooperative behaviours by triggering either self-image concerns (when one sees others’ decisions without being seen) or social-image concerns (when one’s decision is seen by others). A laboratory experiment is designed to compare these two concerns directly, using a four-players finitely repeated public goods experiment on two directed star networks, self-image and social-image networks. The comparison of the players voluntary contributions in both types of networks reveals that their contributing behaviours are statistically indistinguishable. However, the players who belong to the self-image network are more willing to conform with the group behaviours, meaning that they will increase (reduce) the contributions if theirs are below (above) their groups average. Furthermore, I also find evidence that the contributing behaviours are more stable in the self-image networks than in the social-image network.
|Keywords:||Social-image; Self-image; Directed network; Public good experiment|
|JEL:||C92 D19 H41 Z13|
==Notes by yinung==
an ex-post spot market (post-decision & post-rain) in experiments in rural Brazil and a university in England. Queues have greater coordination success than does the spot market.
The most relevant experiment of which we are aware is that of Lefebvre et al. (2012), which studies profits with security-differentiated water rights (mimicking the essence of a queue) versus non-differentiated, equal share rights. The differentiated rights are seen to have profit and risk-management benefits relative to the non-differentiated rights.
|By:||Jordi Brandts (Institutd’AnalisiEconomica(CSIC))
Ayça Ebru Giritligil (Murat Sertel Center for Advanced Economic Studies)
Roberto A. Weber (Department of Economics, University of Zurich)
In many areas of social life individuals receive information about a particular issue of interest from multiple sources. When these sources are connected through a network then proper aggregation of this information by an individual involves taking into account the structure of this network. The inability to aggregate properly may lead to various types of distortions. In our experiment a number of agents all want to find out the value of a particular parameter unknown to all. Agents receive private signals about the parameter and agents can communicate their estimates of the parameter repeatedly through a network, the structure of which is known by all players. We present results from experiments with four different networks. We find that the information of agents who have more outgoing links in a network gets more weight in the information aggregation of the other agents than it optimally should. Our results are consistent with the model of “persuasion bias” of De Marzo et al. (2003) and at odds with an alternative heuristic according to which the most influential agents are those with more incoming links.
==noted by yinung==
|By:||Rebecca Morton (Department of Politics, New York University)
Jean-Robert Tyran (Department of Economics, Copenhagen University)
We investigate experimentally the effects of corrupt experts on information aggregation in committees. We find that non-experts are significantly less likely to delegate through abstention (棄權?) when there is a probability that experts are corrupt. Such decreased abstention, when the probability of corrupt experts is low, actually increases information efficiency in committee decision-making. However, if the probability of corrupt experts is large, the effect is not sufficient to offset the mechanical effect of decreased information efficiency due to corrupt experts. Our results demonstrate that the norm of “letting the expert decide” in committee voting is influenced by the probability of corrupt experts, and that influence can have, to a limited extent, a positive effect on information efficiency.
|Keywords:||Information aggregation, Voting, Asymmetric information, Swing voter’s curse|
|JEL:||C92 D71 D72 D81 D82|
==noted by yinung==
生產落後期的例子: 挖礦 => 金屬生產
… An important aspect of mining is the lag between the time the decision to increase or decrease production
is made and the time the decision actually takes effect in the market. It takes several years for a planned new mine to start producing, …
Numerical Examples 1. l=落後期變長>=4, 價格波動變成發散
Numerical Examples 2. m=預期價格期數變長, 價格波動變成愈穩定
註: m =0 是典型 cobweb 理論, 即只用當期價格, 預測下一期價格
Numerical Examples 3. c= s/d =供給彈性/需求彈性, c 供需彈性比愈大, 價格波動愈不穩定
The classical cobweb theorem is extended to include production lags and price forecasts. Price forecasting based on a longer period has a stabilizing effect on prices. Longer production lags do not necessarily lead to unstable prices; very long lags lead to cycles of constant amplitude. The classical cobweb requires elasticity of demand to be greater than that of supply; this is not necessarily the case in a more general setting. Random shocks are also considered.
* Chiarella (1988)studies a system where expected prices follow adaptive expectations, when the demand curve is linear, while the supply curve is non-linear…[The] paper shows that the system is either (1) stable, (2) unstable but cyclical, or (3) chaotic.
* Chiarella and He (2004). That paper studies the cobweb model from a slightly different point of view (in particular, the supply curve is a specific S-shaped function),
YNY: 這是一篇比較 group 之組成成員能力不同下, 所形成 overbidding 的實驗文獻。
|By:||Philip Brookins (Department of Economics, Florida State University)
John Lightle (Department of Economics, Florida State University)
Dmitry Ryvkin (Department of Economics, Florida State University)
We study experimentally the effects of sorting in contests between groups of heterogeneous players whose within-group efforts are perfect substitutes. The theory predicts that higher aggregate effort will be reached when variation in ability between groups is lower, i.e., by a more balanced sorting. In the experiment, we assign subjects to four types — A, B, C, and D — ranked by their cost of effort, with A having the lowest and D having the highest cost, and conduct contests between two groups of two players each. In the Balanced treatment, (A,D) groups (i.e., groups comprised of a type A and a type D player) compete with (B,C) groups, whereas in the Unbalanced treatment, (A,B) groups compete with (C,D) groups. We find substantial heterogeneity and overinvestment of efforts by all types in both treatments, including the “underdog" (C,D) group which surprisingly is not demoralized by the unbalanced matching. Despite strong overbidding, relative aggregate efforts are remarkably close to equilibrium predictions both between treatments and between groups within each treatment. The results confirm the prediction that balanced sorting leads to higher aggregate effort.
|Keywords:||contest, group, sorting, heterogeneous players, experiment|
|JEL:||C72 C91 M54 D72|
YNY: 這是一篇分析法國2009年實施的 Hadopi law (有在 P2P 網路的軟體盜版行為之法律: 前2次不罰, 第3次偵測到才罰) 的實證影響, 透過網路問卷。
|By:||MICHAEL ARNOLD (Department of Economics,University of Delaware)
ERIC DARMON (CREM, University of Rennes)
SYLVAIN DEJEAN (CREM, LR-MOS, University of La Rochelle)
THIERRY PENARD (CREM, University of Rennes 1 & University of Delaware)
Most developed countries have tried to restrain digital piracy by strength- ening laws against copyright infringement. In 2009, France implemented the Hadopi law. Under this law individuals receive a warning the first two times they are detected illegally sharing content through peer to peer (P2P) networks. Legal action is only taken when a third violation is detected. We analyze the impact of this law on individual behavior. Our theoretical model of illegal be- havior under a graduated response law predicts that the perceived probability of detection has no impact on the decision to initially engage in digital piracy, but may reduce the intensity of illegal file sharing by those who do pirate. We test the theory using survey data from French Internet users. Our econometric results indicate that the law has no substantial deterrent effect. In addition, we find evidence that individuals who are better informed about the law and piracy alternatives substitute away from monitored P2P networks and illegally access content through unmonitored channels.
|Keywords:||Digital Piracy, digital media, Hadopi, three-strikes law, property rights|
|JEL:||L82 O34 K42 D11|