1,053 research outputs found
Interview with Jacqueline DeGroot
No full textJacqueline DeGroot, author of Climax and Worth Any Price, discusses how she came to be a writer, her writing process and sources of inspiration, and her experiences with self-publishing
IMPLICATIONS OF MEASUREMENTS OF E+E--]MU+MU-,E+E- AT PETRA-PEP ENERGIES ON ELECTROWEAK THEORIES
No full textDEGROOT EH, Schildknecht D. IMPLICATIONS OF MEASUREMENTS OF E+E--]MU+MU-,E+E- AT PETRA-PEP ENERGIES ON ELECTROWEAK THEORIES. PHYSICS LETTERS B. 1980;95(1):128-132
From the DeGroot Model to the DeGroot-Non-Consensus Model: The Jump States and the Frozen Fragment States
No full textNon-consensus phenomena are widely observed in human society, but more attention is paid to consensus phenomena. One famous consensus model is the DeGroot model, and there are a series of outstanding works derived from it. By introducing the cognition bias, resulting in over-confidence and under-confidence in the DeGroot model, we propose a non-consensus model, namely the DeGroot-Non-Consensus model. It bridges consensus phenomena and non-consensus phenomena. While different in meaning, the new opinion model can reproduce the DeGroot model’s behaviors and supply a series of interesting non-consensus states. We find frozen fragment states for the over-confident population and time-dependent states for strong interaction strength. In frozen fragment states, the population is polarized into opinion clusters formed by extremists. In time-dependent states, agents jump between two opinions that only differ in the sign, which provides a possible explanation for the swing in opinions in elections and the fluctuations in open questions in the absence of external information. All of these states are summarized in the phase diagrams of the self-confidence and the interaction strength plane. Moreover, the transition scenarios along different parameter paths are studied. Meanwhile, the influence of the nodes’ degree is illustrated in the phase diagrams and the relationship is given. The finite size effect is found in the not quite over-confident population. An interesting phenomenon for small population sizes is that neutral populations with large opinion variance are robust to the fluctuations induced by a finite population size
Granular DeGroot Dynamics -- a Model for Robust Naive Learning in Social Networks
No full textWe study a model of opinion exchange in social networks where a state of the
world is realized and every agent receives a zero-mean noisy signal of the
realized state. It is known from [Golub and Jackson 2010] that under DeGroot
dynamics [DeGroot 1974] agents reach a consensus that is close to the state of
the world when the network is large. The DeGroot dynamics, however, is highly
non-robust and the presence of a single ``stubborn agent'' that does not adhere
to the updating rule can sway the public consensus to any other value. We
introduce a variant of DeGroot dynamics that we call \emph{
-DeGroot}. -DeGroot dynamics approximates standard
DeGroot dynamics to the nearest rational number with as its denominator and
like the DeGroot dynamics it is Markovian and stationary. We show that in
contrast to standard DeGroot dynamics, -DeGroot dynamics is highly
robust both to the presence of stubborn agents and to certain types of
misspecifications.Comment: 35 page
The Asynchronous DeGroot Dynamics
No full textWe analyze the asynchronous version of the DeGroot dynamics: In a connected
graph with nodes, each node has an initial opinion in and an
independent Poisson clock. When a clock at a node rings, the opinion at
is replaced by the average opinion of its neighbors. It is well known that the
opinions converge to a consensus. We show that the expected time to reach -consensus is poly in
undirected graphs and in Eulerian digraphs, but for some digraphs of bounded
degree it is exponential.
Our main result is that in undirected graphs and Eulerian digraphs, if the
degrees are uniformly bounded and the initial opinions are i.i.d., then
for every fixed
. We give sharp estimates for the variance of the limiting
consensus opinion, which measures the ability to aggregate information
(``wisdom of the crowd''). We also prove generalizations to non-reversible
Markov chains and infinite graphs. New results of independent interest on
fragmentation processes and coupled random walks are crucial to our analysis
Private Valuation of a Public Good in Three Auction Mechanisms.
No full textWe evaluate the impact of three auction mechanisms – the Becker–DeGroot–Marschak (BDM) mechanism, the second-price auction (SPA), and the random nth-price auction (NPA) – in the measurement of private willingness-to-pay and willingness-to-accept for a pure public good. Our results show that the endowment effect is lower with the BDM mechanism. In this market mechanism, the effect disappears after a few repetitions. Yet, on a logarithmic scale, the random nth-price auction yields the highest speed of convergence towards equality of welfare indices. We also observe that subjects value public goods in reference to their private subjective benefit derived from their public good funding.auction mechanisms; WTP-WTA disparity; private provisions; public goods;
Private Valuation of a Public Good in Three Auction Mechanisms / Evaluation privée d’un bien public dans trois mécanismes d’enchères
No full textWe evaluate the impact of three auction mechanisms – the Becker–DeGroot–Marschak (BDM) mechanism, the second-price auction, and the random nth-price auction – in the measurement of private willingness-to-pay and willingness-to-accept for a pure public good. Our results show that the endowment effect can be eliminated with repetitions of the BDM mechanism. Yet, on a logarithmic scale, the random nth-price auction yields the highest speed of convergence to welfare indices’ equality. Overall, we observe that subjects value public goods in reference to their private subjective benefit derived from the public good funding.
Nous évaluons l’impact de trois mécanismes d’enchère – le mécanisme Becker-DeGroot-Marschak (BDM), l’enchère au deuxième prix, et l’enchère aléatoire au nième prix – dans l’évaluation des consentement-à-payer et consentement-à-recevoir privés d’un bien public pur. Nos résultats montrent que l’effet de dotation peut être éliminé en répétant le mécanisme BDM. Néanmoins, à l’échelle logarithmique, l’enchère aléatoire au nième prix donne la vitesse de convergence vers l’égalité des indices de bien-être la plus élevée. Plus généralement, nous observons que les sujets d’étude évaluent les biens publics en se référant à l’avantage privé et subjectif qui résulte du financement du bien public.Contingent valuation, WTP-WTA gap, auctions, public good private supply, évaluation contingente, Ecart CAP-CAR, enchères, provision privée des biens publics
Enhanced flux pinning in lithium doped melted grown YBCO by low fluency neutron irradiation
No full textA substantial increase in flux pinning has been reported in Li doped YBCO grains following thermal neutron irradiation. This effect observed in sintered YBCO was attributed to the increased number of defects in the crystal lattice produced by the particles emitted from the fission of 6Li. In this study we report preliminary measurements on the effect of irradiating Li doped melt grown YBCO with thermal neutrons. A single grain was divided into two samples, one of which was then irradiated with ? 1017 neutrons. VSM measurements have revealed that the irradiated sample is far superior at low fields (at best a factor of five increase in Jc at 77 K), but at high fields the magnetic moments become very similar and the irreversibility field remains the same. The absence of fishtail irradiation suggests the introduction of an additional low field pinning mechanism
An experimental study of wine consumers’ willingness to pay for environmental characteristics
No full textThe reduction of pesticides use is becoming a priority for the public authorities in many countries. We conducted an experiment with wine consumers to see whether end-consumers value the dissemination of information about environmentally-friendly production practices. The experiment was devised to (i) evaluate whether there is a premium for environmentally-friendly wines, (ii) determine whether or not consumers are sensitive to label owners who implement and guarantee the environmental actions, (iii) and assess the impact of public messages about the consequences of pesticide use. Some 139 participants were divided randomly into two groups. One group had no specific information about the current state of pesticide use in farming. The other group was given information about pesticide use in farming before making their valuations. Becker-DeGroot-Marshak mechanisms revealed that (i) the environmental signal is valued differently depending on who conveyed the information, and that (ii)dissemination of information about the environmental repercussions of farming methods does not significantly affect willingness-to-pay.Willingness to pay, Wine, Effect of information, Experimental economics, Environment, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,
On the Analysis of the DeGroot-Friedkin Model with Dynamic Relative Interaction Matrices
No full textThis paper analyses the DeGroot-Friedkin model for evolution of the individuals\u27 social powers in a social network when the network topology varies dynamically (described by dynamic relative interaction matrices). The DeGroot-Friedkin model describes how individual social power (self-appraisal, self-weight) evolves as a network of individuals discuss a sequence of issues. We seek to study dynamically changing relative interactions because interactions may change depending on the issue being discussed. In order to explore the problem in detail, two different cases of issue-dependent network topologies are studied. First, if the topology varies between issues in a periodic manner, it is shown that the individuals\u27 self-appraisals admit a periodic solution. Second, if the topology changes arbitrarily, under the assumption that each relative interaction matrix is doubly stochastic and irreducible, the individuals\u27 self-appraisals asymptotically converge to a unique non-trivial equilibrium.This is the extended version of the paper accepted into 20th IFAC World Congress. It contains proofs for the periodic system, and includes arbitrarily issue-varying relative interaction matrices which are all doubly stochasti
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