Heterogeneity and Increasing Returns May Drive Socio-Economic Transitions

There are clear benefits associated with a particular consumer choice for many current markets. For example, as we consider here, some products might carry environmental or `green' benefits. Some consumers might value these benefits while others do not. However, as evidenced by myriad failed attempts of environmental products to maintain even a niche market, such benefits do not necessarily outweigh the extra purchasing cost. The question we pose is, how can such an initially economically-disadvantaged green product evolve to hold the greater share of the market? We present a simple mathematical model for the dynamics of product competition in a heterogeneous consumer population. Our model preassigns a hierarchy to the products, which designates the consumer choice when prices are comparable, while prices are dynamically rescaled to reflect increasing returns to scale. Our approach allows us to model many scenarios of technology substitution and provides a method for generalizing market forces. With this model, we begin to forecast irreversible trends associated with consumer dynamics as well as policies that could be made to influence transition

The dynamics of closeness and betweenness

Although both betweenness and closeness centrality are claimed to be important for the effectiveness of someones network position, it has not been explicitly studied which networks emerge if actors follow incentives for these two positional advantages. We propose such a model and observe that network dynamics differ considerably in a scenario with either betweenness or closeness incentives compared to a scenario in which closeness and betweenness incentives are combined. Considering social consequences, we find low clustering when actors strive for either type of centrality. Surprisingly, actors striving for closeness are likely to reach networks with relatively low closeness and high betweenness, while this is the other way round for actors striving for betweenness. This shows that in both situations the network formation process implies a social dilemma in which the social optimum is not reached by individual optimizing.networks, closeness centrality, betweenness centrality, actor utility, network dynamics, social dilemma

Third-Party Effects

Most theories about effects of social embeddedness on trust define mechanisms that assume someone’s decision to trust is based on the reputation of the person to be trusted or on other available information. However, there is little empirical evidence about how subjects use the information that is available to them. In this chapter, we derive hypotheses about the effects of reputation and other information on trust from a range of theories and we devise an experiment that allows for testing these hypotheses simultaneously. We focus on the following mechanisms: learning, imitation, social comparison, and control. The results show that actors learn particularly from their own past experiences. Considering third-party information, imitation seems to be especially important

Social motives in network formation: an experiment

Literature on network formation typically assumes that people create and remove relations as to maximize their outcome in the network. It is mostly neglected that people might also care about the outcomes of others when creating and removing links. In the current paper, we develop an experiment to investigate whether people show preferences that involve the outcomes of others during network formation. We find varying evidence for effects of social motives in the settings we compare in the experiment. In the final part of the paper, we discuss some explanations for these findings

Выбор режима работы термоэлектрического охлаждающего устройства (ТЭУ), обеспечивающего минимальную интенсивность отказов

Выполнен сравнительный анализ показателей надежности ТЭУ для различных токовых режимов. Показана возможность прогнозирования показателей надежности на стадии проектирования устройств

A state-of-the-art multi-criteria model for drug benefit-risk analysis

Drug benefit-risk analysis is based on firm clinical evidence related to various safety and efficacy outcomes, such as tolerability, treatment response, and adverse events. In this paper, we propose a new approach for constructing a supporting multi-criteria model that fully takes into account this evidence. Our approach is based on the Stochastic Multicriteria Acceptability Analysis (SMAA) methodology, which allows us to compute the typical value judgments that support a decision, to quantify uncertainty, and to compute a comprehensive benefit-risk profile. As an example, we constructed a multi-criteria model for the therapeutic group of second-generation antidepressants. We analyzed Fluoxetine, Paroxetine, Sertraline, and Venlafaxine according to relative efficacy and absolute rates of several common adverse drug reactions using meta-analytical data from the literature. Our model showed that there are clear trade-offs among the four drugs. Based on our experiences from this study, SMAA appears to be a suitable approach for quantifying trade-offs and decision uncertainty in drug benefit-risk analysis.

The dynamics of closeness and betweenness

Although both betweenness and closeness centrality are claimed to be important for the effectiveness of someone's network position, it has not been explicitly studied which networks emerge if actors follow incentives for these two positional advantages. We propose such a model and observe that network dynamics differ considerably in a scenario with either betweenness or closeness incentives compared to a scenario in which closeness and betweenness incentives are combined. Considering social consequences, we find low clustering when actors strive for either type of centrality. Surprisingly, actors striving for closeness are likely to reach networks with relatively low closeness and high betweenness, while this is the other way round for actors striving for betweenness. This shows that in both situations the network formation process implies a social dilemma in which the social optimum is not reached by individual optimizing

Prospective cohort study of routine use of risk assessment scales for prediction of pressure ulcers

Objective To evaluate whether risk assessment scales can be used to identify patients who are likely to get pressure ulcers.Design Prospective cohort study.Setting Two large hospitals in the Netherlands.Participants 1229 patients admitted to the surgical, internal, neurological, or geriatric wards between January 1999 and June 2000.Main outcome measure Occurrence of a pressure ulcer of grade 2 or worse while in hospital.Results 135 patients developed pressure ulcers during four weeks after admission. The weekly incidence of patients with pressure ulcers was 6.2% (95% confidence interval 5.2% to 7.2%). The area under the receiver operating characteristic curve was 0.56 (0.51 to 0.61) for the Norton scale, 0.55 (0.49 to 0.60) for the Braden scale, and 0.61 (0.56 to 0.66) for the Waterlow scale; the areas for the subpopulation, excluding patients who received preventive measures without developing pressure ulcers and excluding surgical patients, were 0.71 (0.65 to 0.77), 0.71 (0.64 to 0.78), and 0.68 (0.61 to 0.74), respectively. In this subpopulation, using the recommended cut­off points, the positive predictive value was 7.0% for the Norton, 7.8% for the Braden, and 5.3% for the Waterlow scale.Conclusion Although risk assessment scales predict the occurrence of pressure ulcers to some extent, routine use of these scales leads to inefficient use of preventive measures. An accurate risk assessment scale based on prospectively gathered data should be developed

Modelling the health-economic impact of the next influenza pandemic in The Netherlands

To optimally develop or adjust national contingency plans to respond to the next influenza pandemic, we developed a decision type model and estimated the total health burden and direct medical costs during the next possible influenza pandemic in the Netherlands on the basis of health care burden during a regular epidemic. Using an arithmetic decision tree-type model we took into account population characteristics, varying influenza attack rates, health care consumption according to the Dutch health care model and all-cause mortality. Actual direct medical cost estimates were based on the Dutch guidelines for pharmaco-economic evaluation. In the base-case scenario with no preventive measure available and an average influenza attack rate of 30%, 4,958,188 influenza infections, 1,552,687 GP consultations, 83,515 hospitalizations and 173,396 deaths will take place in The Netherlands. The burden is highest in adults aged 20 to 64 years. If minimizing the total mortality and sustaining highest net economic returns is the objective, this group needs to be targeted in interventions. (c) 2006 Elsevier Ltd. All rights reserve

The Stability of Exchange Networks

This paper develops a formal model of exchange network stability that combines expected value theory (Friedkin 1995) with the economic literature on network dynamics. We identify stable networks up to size 8 for varying costs and investigate whether they are Pareto efficient and egalitarian. Only a very small number of networks are stable. Odd cycles and networks consisting of dyads and at most one isolate are the only egalitarian, efficient, and stable networks for a large cost range. We show that some of these results are generalizable to networks of any size and are independent of using expected value theory