Expert Information and Majority Decisions

==notes by yinung==
又出現有關 group decision 的研究:
* 專家意見的影響 (在人數多的委員會不佳)
*多數決
Date: 2015-09-23
By: Kohei Kawamura
Vasileios Vlaseros
URL: http://d.repec.org/n?u=RePEc:edn:esedps:261&r=net
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
廣告

Risk taking and information aggregation in groups

==notes by yinung==
終於有人做類似我之前的實驗想法…
reverse confirmation bias:
* 決策者對於來自於其他人的且和自己所獲看法相同之私有訊息, 所放的權重較少; 反之, 對和自己所獲看法「衝突」之私有訊息, 所放的權重較多。
they place less weight on information from others that agrees with their private signal and more weight on conflicting information.
* 在 group 分享訊息但不溝通的決策情境中, 此現象會減少…
Date: 2015
By: Spiro Bougheas
Jeroen Nieboer
Martin Sefton
URL: http://d.repec.org/n?u=RePEc:ehl:lserod:64085&r=net
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

Saving Face and Group Identity

==notes by yinung==
很有趣的保留面子 (saving face) 的實驗?
Date: 2015
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)
URL: http://d.repec.org/n?u=RePEc:hal:wpaper:halshs-01161750&r=net
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.

Are Results of Social- and Self-Image Concerns in Voluntary Contributions Game Similar?

==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

Date: 2015-02
By: Martin Daniel Siyaranamual (Department of Economics, Padjadjaran University)
URL: http://d.repec.org/n?u=RePEc:unp:wpaper:201501&r=net
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

The advantage of resource queues over spot resource markets: decision coordination in experiments under resource uncertainty

Fonseca, Miguel A., Alexander Pfaff, and Daniel Osgood. “The advantage of resource queues over spot resource markets: decision coordination in experiments under resource uncertainty." American Journal of Agricultural Economics 94.5 (2012): 1136-1153. [oxfordjournals.org]; [Open Access PDF]

==Notes by yinung==

本文用實驗法探討灌溉水源 (以 water queues 的形式) 的事前分配 (用 bidding) vs 事後水源拍賣,對生產決策 (種高/低水量需求作物) 之影響。以2007-08 英國 Exeter 大學學生和巴西農業區半工半讀的學生或公務員為受試者,實驗結果證明,事前的 water queues 制度,相對於事後的 spot market 分配水源的制度,有助於提昇效率。
其原因主要是在,決策者面對 environmental and strategic 兩種不確定之下, 可以利用先知道對手對環境不確定之選擇,用來當做生產決策協調之依據。
[引文] The advantage of resource queues over spot markets concerns two types of uncertainty, environmental and strategic.
(較早寫的)
此篇用經濟實驗法, 研究農民在灌溉用水不確定下之決策; 投入種子、肥料、整地的成本, 但利潤取決於不確定供水。在環境不確定 (雨量多寡) 前,先以 bidding (water queues) 決定用水優先序,可做為投入種植決策之協調機制,使得在事前 water queues 制度下, 比雨量確定後才拍賣決定水權制度更有效率。

==abstract==

Farmers have to make key decisions, such as which crops to plant or whether to prepare the soil, before knowing how much water they will get. They face losses if they make costly decisions but do not receive water, and they may forego profits if they receive water without being prepared. We consider the coordination of farmers’ decisions, such as which crops to plant or whether to prepare the soil when farmers must divide an uncertain water supply. We compare ex-ante queues (pre-decision) to
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.

==References==

Lefebvre, M., L. Gangadharan, and S. Thoyer. 2012. “Do Security-Differentiated Water Rights Improve the Performance of Markets?” American Journal of Agricultural Economics. doi:10.1093/ajae/aas060.
本文回顧到這篇:
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.

An Experimental Study of Persuasion Bias and Social Influence in Networks

==Noted by yinung==
這篇和我之前的想法有點像, 不同處在於, 我是以小團體 (例如委員會) 中的資訊發表 (或擴散) 模式來探討, 並以多數決、一致決、不同意見發表能見度機率…來建構實驗; 這篇則是以連結數為主的設計 (比較適合一般網路世界)。
突然產生一個研究想法, 若 one of the committee members 想要增加他自已的影響力, 他才有過度發表 (宣傳) 他的意見的動機; 故在實驗設計中:
1. 每個 agent 有自已的 private signals (各有準確的機率), 或某些人還有 public reputation (比自己的 private signal 準確率高/低)
2. 每個 agent 動機都是為 group 好 / 加入 agent 自已的 utility, 認同他的人愈多, 則 utility 愈大)
3. 這個特別的 agent 可能是經理, 主席, 社團領袖, 只是普通的組員 (強調不同決策形成模式)
    經理: 獨裁但負全責
    主席: 多數決, 責任分擔
    社團領袖: 共識決, , 責任分擔
    普通組員: 非意見領袖
Date: 2014-10
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)
URL: http://d.repec.org/n?u=RePEc:beb:wpbels:201403&r=net
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.

Corruption in Committees: An Experimental Study of Information Aggregation through Voting

==noted by yinung==

此實驗的主題是委託專家決定的投票決策慣例是否正確!
這和我之前構想過的 committee (group) 決策行為之實驗有關
委員會中, 有專家和非專家。在專家公正的情況下,非專家棄權是正確的決定; 但若專家可能有 bias, 則非專家 (uninformed) 的投票可以抵消 biased 決策的形
Q1: 本文所提之 information efficiency 定義為何?
==引文==
Individuals often vote in situations where they have less than perfect information about the choices before them. Moreover, information is typically asymmetrically distributed, where somevoters have better knowledge about the choices than others.
專家委員會

one norm is to delegate to the so-called experts, the individuals who are known to have better information
關鍵投票 vote is pivotal, either forces a tie or breaks a tie.
無充分資訊的投票者亦導致不利結果
the uninformed voter’s participation has resulted in a worse outcome.
相關文獻
Feddersen and Pesendorfer (1996, 1999), in a seminal set of papers, pointed out that voters with low information levels should avoid this “swing voter’s curse " and rationally abstain, delegating the choice to fully informed voters.
Battaglini, Morton, and Palfrey (2008, 2010) Önd support for such “delegation through abstention."(以棄權方式來授權)
Using experiments, Morton and Tyran show that the equilibria with delegation through abstention are attractive to voters. Even when it is informationally efficient for all voters to participate, about half the time less informed voters abstain, delegating thedecision to more informed voters. (讓專業決定: let the experts decide)
Date: 2014-09-07
By: Rebecca Morton (Department of Politics, New York University)
Jean-Robert Tyran (Department of Economics, Copenhagen University)
URL: http://d.repec.org/n?u=RePEc:kud:kuiedp:1418&r=net
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

Cobweb Theorems with Production Lags and Price Forecasting

Daniel Dufresne and Felisa Vázquez-Abad (2013). Cobweb Theorems with Production Lags and Price Forecasting. Economics: The Open-Access, Open-Assessment E-Journal, 7 (2013-23): 1—49. http://dx.doi.org/10.5018/economics-ejournal.ja.2013-23
[下載 PDF: Download (pdf, 800.8 kB)](SSCI 期刊)

==noted by yinung==

這篇是理論性文章,數學用了不少,並不好讀。

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, …

主要研究發現:

Numerical Examples 1. l=落後期變長>=4, 價格波動變成發散

 image

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

image

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

image

==original abstract==

(yinung 翻譯的)
在較長期的價格預測下,對價格有穩定作用。較長生產落後期並不會導致價格不穩。很長的生產落後期可導致波動之循環。

Abstract
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.

==references==

* 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),

An experimental study of sorting in group contests

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。

Date: 2014-01
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)
URL: http://d.repec.org/n?u=RePEc:fsu:wpaper:wp2014_01_01&r=net
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

Graduated Response Policy and the Behavior of Digital Pirates: Evidence from the French Three-Strike (Hadopi) Law

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。

Date: 2014
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)
URL: http://d.repec.org/n?u=RePEc:dlw:wpaper:14-07.&r=net
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