A network experiment in continuous time: The influence of link costs

In recent work on non-cooperative network formation star-shaped networks play an important role. In a particular theoretical model of Bala and Goyal (2000) center-sponsored stars are the only strict Nash networks. In testing this theoretical model, Falk and Kosfeld (2003) do not find experimental evidence that players select the center-sponsored star. Based on a slight modification of Bala and Goyal’s model, we design a network formation experiment in which, depending on link costs, periphery-sponsored stars and the empty network are the only strict Nash networks. We observe that almost all groups not only reach a strict Nash network once but also switch the center player in periphery-sponsored stars several times. The main innovation in our experiment is to use a continuous time framework which we believe to be a more realistic setting to study behavior in network formation situations and which makes coordination on stars much easier than simultaneous strategy adaptation in discrete time. Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s10683-006-9125-1. JEL Classification C72 · C92 · D81     

Experimental evidence on coverage choices and contract prices in the market for corporate insurance

In this paper, we present experimental evidence on the effect adverse selection has on coverage choices and pricing in corporate insurance markets. Two sets of experimental data, each generated by experiments utilizing a specific parameterization of a corporate insurance decision, are presented to gauge these effects. In the first, subject behavior conforms to a unique equilibrium in which high risk firms choose higher coverage and contracts are priced accordingly. Insurers act competitively and convergence to equilibrium behavior is marked. In the second set, there is little evidence that subject behavior is consistent with either of the two equilibrium outcomes supported by the experimental setting—pooling by fully insuring losses and pooling by self insuring. JEL Classification C90, G14, G22 Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s10683-006-9152-y.     

Bias-corrected estimates of reduction of post-surgery length of stay and corresponding cost savings through the widespread national implementation of fast-tracking after liver transplantation: a quasi-experimental study

Background: Fast-tracking is an approach adopted by Mayo Clinic in Florida’s (MCF) liver transplant (LT) program, which consists of early tracheal extubation and transfer of patients to surgical ward, eliminating a stay in the intensive care unit in select patients. Since adopting this approach in 2002, MCF has successfully fast-tracked 54.3% of patients undergoing LT.

Objectives: This study evaluated the reduction in post-operative length of stay (LOS) that resulted from the fast-tracking protocol and assessed the potential cost saving in the case of nationwide implementation.

Methods: A propensity score for fast-tracking was generated based on MCF liver transplant databases during 2011–2013. Various propensity score matching algorithms were used to form control groups from the United Network of Organ Sharing Standard Analysis and Research (STAR) file that had comparable demographic characteristics and health status to the treatment group identified in MCF. Multiple regression and matching estimators were employed for evaluation of the post-surgery LOS. The algorithm generated from the analysis was also applied to the STAR data to determine the proportion of patients in the US who could potentially be candidates for fast-tracking, and the potential savings.

Results: The effect of the fast-tracking on the post-transplant LOS was estimated at approximately from 2.5 (p-value?=?0.001) to 3.2 (p-value?Conclusion: The fast-track program was found to be effective in reducing post-transplant LOS, although the reduction appeared to be less than previously reported. Nationwide implementation of fast-tracking could result in substantial cost savings without compromising the patient outcome.     

Global public goods and unilateral matching mechanisms

While conventional agreements on international public goods require bilateral or multilateral cooperation, we show that unilateral action through matching mechanisms with a self‐commitment device can possibly generate Pareto‐improving outcomes. Even without commitment, unilateral matching may also benefit both players at corner situations. We further characterize the conditions under which this desirable outcome is achieved, particularly highlighting the role of the income distribution and its interplay with the preferences. Moreover, we propose a variant of unilateral matching that can generate Pareto‐improving outcomes regardless of the preferences and the income distribution, indicating that income inequality may not be an obstacle for improving public good provision through unilateral matching.     

The impact of endowment heterogeneity and origin on contributions in best-shot public good games

Economists and psychologists have long argued the origin of wealth influences individual behavior. In a previous study (Cherry et al., 2005), we found the origin of endowment did not significantly affect behavior in linear public good games with summation contribution technology. In such games, however, both Nash behavior (everybody gives nothing) and social optimal behavior (everybody gives the entire endowment) call for symmetric levels of contributions. Results from this new study indicate that the origin of wealth might matter in more asymmetric situations, such as in a best-shot public good game with heterogeneous groups. Electronic Supplementary Material Supplementary material is available in the online version of this article at . JEL Classification C72, C92, H41     

Does studying abroad enhance employability?

Over 200,000 European students study abroad under the Erasmus programme. It appears that studying abroad may impart skills which are helpful for professional careers after graduation. Approximately, 54% of European students report that participation in the Erasmus exchange programme helped them to obtain a first job; however, interestingly, those from Central and Eastern European countries report it much more often—in 73% of cases. The aim of this paper is to find out whether studying abroad enhances the employability of higher education graduates in Poland. Using the propensity score matching method and data from a nationwide tracer survey of Polish graduates, we find that Polish students who completed at least one semester of their studies abroad do not benefit in terms of a higher employment rate after graduation.     

Identity,homophily and in-group bias

Many instances of social interaction display either or both of the following well-documented phenomena. People tend to interact with similar others (homophily). They also tend to treat others of shared social identity more favorably (in-group bias). While both phenomena involve some degree of discrimination towards others, a systematic study of their relations and interplay is yet missing. In this paper we report the findings of an experiment designed to address this issue. Participants are exogenously and randomly assigned to one of two groups. Subsequently they play a sequence of eight games with either an in-group or an out-group member. In treatment EXO in- and out-group matches are formed exogenously, while in ENDO participants can choose between in- and out-group matches. We find strong evidence of in-group bias in EXO, and strong evidence of homophily in ENDO. In-group biases, however, either decrease or disappear altogether under endogenous matching. We show that self-selection of homophilous agents into in-group matches cannot explain this fact. We also find that homophily is strongly correlated with risk aversion, and we build on this evidence to derive a rationale for both the existence of homophily and the disappearance of in-group biases under endogenous matching.     

Matching mechanisms and matching quality: Evidence from a top university in China

We compare competing college admission matching mechanisms that differ in preference submission timing (pre-exam, post-exam but pre-score, or post-score) and in matching procedure (Boston (BOS) and serial dictatorship (SD) matching). Pre-exam submission asks students to submit college preferences before entrance exam scores are known, whereas post-score (post-exam) submission removes (reduces) score uncertainties. Theoretical analyses show that although mechanisms with post-score submission or SD matching are ex-post fair and efficient, they are not so ex-ante. Instead, the mechanism with pre-exam submission and BOS matching can be more fair and efficient ex-ante. These hypotheses are supported by empirical test on data from a top school at a top-ranked Chinese university with identification based on temporal and provincial changes. We find that although students admitted under the pre-exam BOS mechanism have lower college entrance exam scores than students admitted through other mechanisms on average, they exhibit similar or even better college academic performance.     

Testing subgame perfection apart from fairness in ultimatum games

We present an experiment designed to separate the two commonplace explanations for behavior in ultimatum games—subjects’ concern for fairness versus the failure of subgame perfection as an equilibrium refinement. We employ a tournament structure of the bargaining interaction to eliminate the potential for fairness to influence behavior. Comparing the results of the tournament game with two control treatments affords us a clean test of subgame perfection as well as a measure fairness-induced play. We find after 10 iterations of play that about half of all non-subgame-perfect demands are due to fairness, and the rest to imperfect learning. However, as suggested by models of learning, we also confirm that the ultimatum game presents an especially difficult environment for learning subgame perfection. Electronic Supplementary Material Supplementary material is available in the online version of this article at . JEL Classification C91, D64, J52     

Counterintuitive number effects in experimental oligopolies

Recent theoretical research on oligopolistic competition suggests that under certain conditions prices increase with the number of competing firms. However, this counterintuitive result is based on comparative-static analyses which neglect the importance of dynamic strategies in naturally-occurring markets. When firms compete repeatedly, supra-competitive prices can become sustainable but this is arguably more difficult when more firms operate in the market. This paper reports the results of laboratory experiments investigating pricing behavior in a setting in which (static) theory predicts the counterintuitive number effect. Under a random matching protocol, which retains much of the one-shot nature of the model, the data corroborates the game-theoretic prediction. Under fixed matching duopolists post substantially higher prices, whereas prices in quadropolies remain very similar. As a result, the predicted effect is no longer observed, and towards the end the reverse effect is observed.

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Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.      

Stability of risk preference parameter estimates within the Becker-DeGroot-Marschak procedure

This paper reports new data from both selling and buying versions of the Becker-DeGroot-Marschak (BDM) procedure. First, when using the selling version of BDM, the cross-sectional mean of CRRA risk preference parameter estimates shifts from a value consistent with “as if” risk-seeking behavior in the early baseline to a value closer to “as if” risk neutrality in the late baseline. Second, when using the buying version of BDM, the cross-sectional mean of CRRA risk preference parameter estimates does not appear to change over time in a statistically significant manner. The cross-sectional mean from the late baseline of the buying version of BDM is closer to “as if” risk neutrality and to the late baseline estimates from the selling version of BDM than it is to either early baseline estimates from the selling version of BDM or typical estimates from the first price auction. Use of dominated offers is correlated with deviations from “as if” risk neutrality; this suggests the possibility that the early deviations from “as if” risk neutrality reflect errors. Electronic Supplementary Material Supplementary material is available in the online version of this article at . JEL Classification D80     

Misperceiving the value of information in predicting the performance of others

Economic models typically allow for “free disposal” or “reversibility” of information, which implies non-negative value. Building on previous research on the “curse of knowledge” we explore situations where this might not be so. In three experiments, we document situations in which participants place positive value on information in attempting to predict the performance of uninformed others, even when acquiring that information diminishes their earnings. In the first experiment, a majority of participants choose to hire informed—rather than uninformed—agents, leading to lower earnings. In the second experiment, a significant number of participants pay for information—the solution to a puzzle—that hurts their ability to predict how many others will solve the puzzle. In the third experiment, we find that the effect is reduced with experience and feedback on the actual performance to be predicted. We discuss implications of our results for the role of information and informed decision making in economic situations. Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s10683-006-9128-y. JEL Classification C91, D83     

Finding partners for complex system innovations through a trans-sectoral ‘matchmaking platform’

Complex system innovations require the concurrent implementation of trans-sectoral co-innovations. The case of fuel cell vehicle development in Germany may serve as an expedient example for this necessity to develop multiple innovative components within largely disconnected ‘technology islands’. The diagonal cooperation among organisations from formerly non-cooperating industries (i.e. from within those technology islands) that so far have not shared a common knowledge base, however, is hindered by structural information deficits, making it difficult to identify the ‘right’ cooperation partners. Based on the requirements as identified in the case study, we therefore propose a ‘matchmaking platform’ that aims at fostering a trans-sectoral dialogue by providing systematically generated corporate capability profiles of organisations with promising cooperation potential. The matching is grounded on factors derived from resource- and market-based theory.     

Choosing propensity score matching over regression adjustment for causal inference: when,why and how it makes sense

Summary

This study identified when regression adjustment fails to adjust adequately for differences in observed covariates and where propensity score matching is the only alternative.

Multivariate analysis might fail to adjust for observed confounders if:

• 1. The means of the propensity scores in the two groups are more than one-half a standard deviation apart unless distributions of the covariates in both groups are nearly symmetric, sample sizes of the two groups are approximately the same and distributions of the covariates in the two groups have similar variances;

• 2. The ratio of the propensity score variances in the two groups is significantly different from one;

• 3. The ratio of residual variances in the two groups after adjusting for the propensity score is significantly different from one.

Conducted retrospective analysis showed that the treatment effect would be an estimated $305 (or 26%) less if the misspecified outcome model had been chosen.     

“Si él lo necesita”: Gypsy fairness in Vallecas

“Si él lo necesita” (if he really needs it) was the most common argument given by the subjects who accepted the zero offer in the ultimatum game (strategy method) during experiments conducted among illiterate (adult) gypsies in Vallecas, Madrid. Interestingly the acceptance of the zero offer was not a rare case but, in contrast, was the modal value. This is even more remarkable if we consider that the 97% of the subjects proposed the equal split. Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s10683-006-9126-0. JEL Classification D63 · D64 · C93 · J15     

Observability and overcoming coordination failure in organizations: An experimental study

Motivated by problems of coordination failure in organizations, we examine how overcoming coordination failure and maintaining coordination depend on the ability of individuals to observe others’ choices. Subjects’ payoffs depend on coordinating at high effort levels in a weak-link game. Treatments vary along two dimensions. First, subjects either start with low financial incentives for coordination, which typically leads to coordination failure, and then are switched to higher incentives or start with high incentives, which usually yield effective coordination, and are switched to low incentives. Second, as the key treatment variable, subjects either observe the effort levels chosen by all individuals in their experimental group (full feedback) or observe only the minimum effort (limited feedback). We find three primary results: (1) When starting from coordination failure the use of full feedback improves subjects’ ability to overcome coordination failure, (2) When starting with good coordination the use of full feedback has no effect on subjects’ ability to avoid slipping into coordination failure, and (3) History-dependence, defined as dependence of current effort levels on past incentives, is strengthened by the use of full feedback. Electronic Supplementary Material Supplementary material is available in the online version of this article at . JEL Classification C92, D23, J31, L23, M52     

产学研合作知识共享影响因素实证研究——以知识共享情境为调节变量

本文通过对产学研合作以及知识共享的相关理论进行归纳和分析,探讨了产学研合作知识共享过程中学研机构、企业作为知识主体的表现以及知识情境的影响要素方面的问题.在此基础上,基于Albino提出的知识共享基础模型,构建了以企业与学研机构知识共享情境匹配度为调节变量的产学研合作知识共享研究框架.通过30余家企业、院校、科研院所224份调查问卷的数据分析,对产学研知识共享能力与知识共享绩效的作用关系,以及知识共享情境在其中的调节作用进行了探讨.结果显示:学研机构能力、企业能力以及产学研交互关系与共享绩效显著正相关,且随着企业与学研机构知识共享情境匹配度的提升,对绩效的影响越大.该结果表明共享情境调节产学研合作知识共享能力对共享绩效的影响.     

中国信贷市场匹配机制的再设计

我国的银行信贷市场呈现二元结构--目标客户与非目标客户信贷市场.两者有着不同的运行机制.目标客户信贷市场的议价过程存在一个类似企业"求婚"的递延接受程序,市场的运行结果稳定.非目标客户信贷市场不存在导致稳定结果的分散化匹配程序,市场广度和深度不够.为提高非目标客户信贷市场的稳定性和运行效率,我们建议通过公布银行信贷方案、设立非目标客户信贷中心、设立中央化的匹配清算所等,把分散化的议价过程变成中央化的匹配程序,从而完善和降低中小企业的交易成本,为中小企业的发展拓展广阔空间.     

Contracting inside an organization: An experimental study

In this paper we propose and test a contracting mechanism, Multi-Contract Cost Sharing (MCCS), for use in the management of a sequence of projects. The mechanism is intended for situations where (1) the contractor knows more about the true costs of various projects than does the contracting agency (adverse selection), and (2) unobservable effort on the part of the contractor may lead to cost reductions (moral hazard). The proposed process is evaluated in an experimental environment that includes the essential economic features of the NASA process for the acquisition of Space Science Strategy missions. The environment is complex and the optimal mechanism is unknown. The design of the MCCS mechanism is based on the optimal contract for a simpler related environment. We compare the performance of the proposed process to theoretical benchmarks and to an implementation of the current NASA ‘cost cap’ procurement process. The data indicate that the proposed MCCS process generates significantly higher value per dollar spent than using cost caps, because it allocates resources more efficiently among projects and provides greater incentives to engage in cost-reducing innovations. Electronic Supplementary Material Supplementary material is available in the online version of this article at . JEL Classification C72, C92, D82, L32     

Subsidizing charitable contributions: a natural field experiment comparing matching and rebate subsidies

We report the results of a field experiment conducted in conjunction with a mailed fundraising campaign of a nonprofit organization. The experiment is designed to compare the response of donors to subsidies in the form of matching amounts or rebated amounts. Matching subsidies are used by many corporations as an employee benefit; the US federal tax system encourages giving using a rebate subsidy by making donations tax deductible. The design includes a control group and two levels of subsidy of each type. Our main result is that matching subsidies result in larger total donations to charities than rebate subsidies, a result that is qualitatively similar to the lab findings. The estimated price elasticities for the matching subsidy are very similar to (and insignificantly different from) the lab experiments, while rebate subsidies lead to lower contributions in the field than in the lab. Since rebates in the field involve substantial lags and additional complications as compared with the “instant rebates” of the lab, this latter difference is not unexpected. The matching results are an important step in validating lab estimates of responsiveness to subsidies of charitable giving.

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Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.