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![Research design
a–c We evaluated the efficiency of juries with N jurors by comparing the verdict accuracy with the deliberation time (a) using the majority-vote model with noise on a complete graph (b). The verdict accuracy 〈Accuracy〉 was defined as whether the jury verdicts σjury was the same as the verdicts hypothetically made by the full community members σComm. We then quantified the beneficial effect of N jurors on the verdict accuracy Δ〈Accuracy〉N by calculating how better the verdict accuracy in the N-juror system 〈Accuracy〉N was compared to 〈Accuracy〉2, the accuracy of the most basic collective decision-making system. The deliberation time T was summarised by its median value 〈T〉 because T showed a skewed distribution (c). Finally, we estimated the jury efficiency by calculating the ratio of Δ〈Accuracy〉 to 〈T〉. In the majority-vote model (b), the jurors change their opinions to the majority opinion at a time point with a probability 1–q or to the minor one with a probability q. If the opinion in the jury is equally divided, the jurors change their opinions randomly. The q is a noise parameter, which is also stated as social temperature (Vilela and Stanley, 2018) and anti-conformity index (Nowak and Sznajd-Weron, 2019). The FMajor represents the proportion of the major opinion in the entire community. d. The graph shows an association between the number of jurors N and the critical noise qc in the majority-vote model on complete graphs (Chen et al., 2015). In the range of q was set to [0.05, 0.2] so that q is less than qc even when the number of the jurors is relatively small (e.g., N ~ 10).](publication/343609425/figure/fig2/AS:963466848378925@1606719805993/Research-design-a-c-We-evaluated-the-efficiency-of-juries-with-N-jurors-by-comparing-the.png)
Research design a–c We evaluated the efficiency of juries with N jurors by comparing the verdict accuracy with the deliberation time (a) using the majority-vote model with noise on a complete graph (b). The verdict accuracy 〈Accuracy〉 was defined as whether the jury verdicts σjury was the same as the verdicts hypothetically made by the full community members σComm. We then quantified the beneficial effect of N jurors on the verdict accuracy Δ〈Accuracy〉N by calculating how better the verdict accuracy in the N-juror system 〈Accuracy〉N was compared to 〈Accuracy〉2, the accuracy of the most basic collective decision-making system. The deliberation time T was summarised by its median value 〈T〉 because T showed a skewed distribution (c). Finally, we estimated the jury efficiency by calculating the ratio of Δ〈Accuracy〉 to 〈T〉. In the majority-vote model (b), the jurors change their opinions to the majority opinion at a time point with a probability 1–q or to the minor one with a probability q. If the opinion in the jury is equally divided, the jurors change their opinions randomly. The q is a noise parameter, which is also stated as social temperature (Vilela and Stanley, 2018) and anti-conformity index (Nowak and Sznajd-Weron, 2019). The FMajor represents the proportion of the major opinion in the entire community. d. The graph shows an association between the number of jurors N and the critical noise qc in the majority-vote model on complete graphs (Chen et al., 2015). In the range of q was set to [0.05, 0.2] so that q is less than qc even when the number of the jurors is relatively small (e.g., N ~ 10).
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For judicial democracy, many societies adopt jury trials, where verdicts are made by a unanimous vote of, conventionally, 12 lay citizens. Here, using the majority-vote model, we show that such jury sizes achieve the best balance between the accuracy of verdicts and the time spent for unanimous decision-making. First, we identify two determinants o...
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... В своей статье «Численное исследование эффективного размера жюри» Takamitsu Watanabe пришел к выводу, что эффективный состав жюри это 11,8+3,0 [2]. Другими словами, состав жюри возможен при количестве 9, 12, 15 человек. ...
he authors, based on a comparative analysis of the criminal procedure laws of the USA and Kazakhstan, studied the issues of the activity of courts with the participation of jurors. The choice of the US experience in considering criminal cases by a jury was not accidental, since the USA is the state to use a jury trial and already has its own legal history that is different from the UK. In the course of the analysis, the authors revealed three aspects such as the selection of jurors, the number of jurors, and the voting procedure during sentencing. The selection of jurors under US law has its advantages in comparison with the legislation of the Republic of Kazakhstan in terms of simplifying the selection and the right to refuse to participate as a juror. On the issue of the number of jurors, taking into account the US experience, we believe it is possible to reduce them from 12 to 9 and in some cases to 7 jurors. On the issue of majority voting or unanimous voting, based on the experience of the United States, we hold the opinion on the importance of voting by unanimous decision. Based on the positive experience of the USA, the authors proposed several amendments not only to the criminal procedure legislation of Kazakhstan but also to the Constitution of the Republic of Kazakhstan. Thus, the authors believe it is necessary to expand the category of criminal cases considered by a court with the participation of jurors, to improve the selection procedure and voting procedure. As well as the possibility of consideration of civil cases by a court with the participation of jurors. We believe all these amendments will have a positive effect in protecting the constitutional rights of citizens and building a rule-of-law state.
... Complex networks consist of a natural preference for the study of real-world complex systems, such as climate analysis, biological neural connections, the World Wide Web, public transportation, airline networks, financial markets, and social networks (29)(30)(31)(32)(33)(34)(35)(36)(37)(38). In this context, random graph networks describe the topology of a set of N nodes connected with chance p, thus introducing a fundamental probability distribution across graphs. ...
We investigate financial market dynamics by introducing a heterogeneous agent-based opinion formation model. In this work, we organize individuals in a financial market according to their trading strategy, namely, whether they are noise traders or fundamentalists. The opinion of a local majority compels the market exchanging behavior of noise traders, whereas the global behavior of the market influences the decisions of fundamentalist agents. We introduce a noise parameter, q, to represent the level of anxiety and perceived uncertainty regarding market behavior, enabling the possibility of adrift financial action. We place individuals as nodes in an Erdös-Rényi random graph, where the links represent their social interactions. At any given time, individuals assume one of two possible opinion states ±1 regarding buying or selling an asset. The model exhibits fundamental qualitative and quantitative real-world market features such as the distribution of logarithmic returns with fat tails, clustered volatility, and the long-term correlation of returns. We use Student's t distributions to fit the histograms of logarithmic returns, showing a gradual shift from a leptokurtic to a mesokurtic regime depending on the fraction of fundamentalist agents. Furthermore, we compare our results with those concerning the distribution of the logarithmic returns of several real-world financial indices.
... A third possible limitation is jury size; specifically, juries in the present study contained six persons-the constitutional minimum in the United States. Compared with smaller juries, larger juries are more diverse, collectively remember more evidence, and produce verdicts that are more predictable and in line with community sentiment; however, they also deliberate longer and reduce the likelihood of individual participation (Bornstein & Greene, 2017;Watanabe, 2020). Statistical models show that optimal jury sizebalancing considerations like verdict accuracy and efficiency (that is, costs to both courts and jurors themselves)-varies depending on community factors (for example, opinion homogeneity) but is about nine to 12 (King & Nesbit, 2009;Watanabe, 2020). ...
... Compared with smaller juries, larger juries are more diverse, collectively remember more evidence, and produce verdicts that are more predictable and in line with community sentiment; however, they also deliberate longer and reduce the likelihood of individual participation (Bornstein & Greene, 2017;Watanabe, 2020). Statistical models show that optimal jury sizebalancing considerations like verdict accuracy and efficiency (that is, costs to both courts and jurors themselves)-varies depending on community factors (for example, opinion homogeneity) but is about nine to 12 (King & Nesbit, 2009;Watanabe, 2020). Given larger juries' tendency to recall more evidence and discuss it more accurately (Saks & Marti, 1997), we expect that the effects of jailhouse informant testimony observed here would, if anything, be less with larger juries. ...
This study investigated the impact of jailhouse informant testimony on mock juries. In addition to allowing for jury deliberations, individual judgments (as measured in most prior research) were examined. Two hundred ninety-one undergraduates, in five- to six-member mock juries, heard a fictional murder trial summary in one of three conditions: jailhouse informant testified after receiving an incentive, jailhouse informant testified after receiving no incentive, or no jailhouse informant testimony. Participants made predeliberation judgments, deliberated on a verdict, and made postdeliberation judgments. The primary results showed that there were more guilty verdicts for juries that heard jailhouse-informant testimony than for those that did not hear such testimony. This relationship was fully mediated by perceptions of the defendant (e.g., sympathy for and credibility of). In addition, jury deliberations often produced a change in verdict; those who gave an initial guilty verdict were more likely to switch to not guilty after deliberation. Finally, cognitive network analyses showed that jailhouse informant testimony was the focus of jury deliberations for both guilty (viewed the testimony as reliable) and not guilty (viewed the testimony as unreliable) verdicts. Results are discussed in terms of the importance of how jailhouse informant testimony can influence jury deliberations in both a positive and negative way.
A prominent and publicly influential literature challenges the quality of democratic decision making, drawing on political science findings with specific claims about the ubiquity of cognitive bias to lament citizens’ incompetence. A competing literature in democratic theory defends the wisdom of crowds, drawing on a cluster of models in support of the capacity of ordinary citizens to produce correct outcomes. In this Letter, we draw on recent findings in psychology to demonstrate that the former literature is based on outdated and erroneous claims and that the latter is overly sanguine about the circumstances that yield reliable collective decision making. By contrast, “interactionist” scholarship shows how individual-level biases are not devastating for group problem solving, given appropriate conditions. This provides possible microfoundations for a broader research agenda similar to that implemented by Elinor Ostrom and her colleagues on common-good provision, investigating how different group structures are associated with both success and failure in democratic decision making. This agenda would have implications for both democratic theory and democratic practice.
