Applications of zero-inflated count data models have proliferated in health economics. However, zero-inflated Poisson or zero-inflated negative binomial maximum likelihood estimators are not robust to misspeci*fication. This paper proposes Poisson quasi-likelihood estimators as an alternative. These estimators are consistent in the presence of excess zeros without having to specify the full distribution. The advantages of the Poisson quasi-likelihood approach are illustrated in a series of Monte Carlo simulations and in an application to the demand for health services.
Employment contracts are often incomplete, leaving many responsibilities subject to workers’ discretion. High work morale is therefore essential for sustaining voluntary cooperation and high productivity in firms. We conducted a field experiment to test whether workers reciprocate wage cuts and raises with low or high work productivity. Wage cuts had a detrimental and persistent impact on productivity, reducing average output by more than 20 percent. An equivalent wage increase, however, did not result in any productivity gains. The results from an additional control experiment with high monetary performance incentives demonstrate that workers could still produce substantially more output, leaving enough room for positive reactions. Altogether, these results provide evidence consistent with a model of reciprocity, as opposed to inequality aversion.
Some of the most beautiful results in mechanism design depend crucially on Myerson's (1981) regularity condition. E.g., the second-price auction with reserve price is revenue maximizing only if the type distribution is regular. This paper offers two main results. First, an interpretation of regularity is developed in terms of being the next to fail. Second, using expanded concepts of concavity, a tight sufficient condition on the density function is formulated. New examples of parameterized distributions are shown to be regular. Applications include standard design problems, optimal reserve prices, the analysis of bidding data, and multidimensional types.
What determines reciprocity in employment relations? We conducted a controlled field experiment to measure the extent to which monetary and non-monetary gifts affect workers’ performance. We find that non-monetary gifts have a much stronger impact than monetary gifts of equivalent value. We also observe that when workers are offered the choice, they prefer receiving money but reciprocate as if they received a non-monetary gift. This result is consistent with the common saying, "it’s the thought that counts". We underline this point by showing that also monetary gifts can effectively trigger reciprocity if the employer invests more time and effort into the gift’s presentation.
This paper examines the role of cooperativeness and impatience in the exploitation of common pool resources (CPRs) by combining laboratory experiments with field data. We study fishermen whose main, and often only, source of income stems from the use of fishing grounds with open access. The exploitation of a CPR involves a negative interpersonal and inter-temporal externality because individuals who exploit the CPR reduce the current and the future yield both for others and for themselves. Economic theory – which assumes the existence of general across-situational traits – thus predicts that fishermen who exhibit more cooperative and less impatient behavior in the laboratory should be less likely to exploit the CPR, which our findings confirm. We thus corroborate the economic theory and extend the scope of other-regarding preference theories to crucial economic decisions with lasting consequences for the people involved. In addition, we establish cooperativeness and impatience as two distinct traits related to resource conservation in the field and validate laboratory preference measures.
Ein Zusammenbruch des Euro und sogar der EU wäre nicht das Ende Europas. Die Länder würden sich schnell auf neue Vereinbarungen einigen, je nach Interessenlage. Ein Zusammenschluss Europas unter Verwendung solch flexibler, sich überlappender Verträge auf funktionaler Ebene wäre wünschenswert.
This study presents a simple empirical framework suitable for describing individuals' subjective evaluations of wage inequality and their normative assessment of market justice. The framework is illustrated using survey data from the International Social Survey Program from Switzerland. Although most individuals accept the fact that there are quite large pay differentials across different occupations, they would still prefer a more equal distribution of market wages. The empirical analysis further shows that financial self-interest, normative beliefs, and perceptions of how wages are determined all have an impact on the assessment of market justice. Finally, subjective inequality measures and the assessment of market justice turn out to be substantive predictors of individuals' general support for the welfare state and their party identification.
Modulations of sensory processing in early visual areas are thought to play an important role in conscious perception. To date, most empirical studies focused on effects occurring before or during visual presentation. By contrast, several emerging theories postulate that sensory processing and conscious visual perception may also crucially depend on late top-down influences, potentially arising after a visual display. To provide a direct test of this, we performed an fMRI study using a postcued report procedure. The ability to report a target at a specific spatial location in a visual display can be enhanced behaviorally by symbolic auditory postcues presented shortly after that display. Here we showed that such auditory postcues can enhance target-specific signals in early human visual cortex (V1 and V2). For postcues presented 200 msec after stimulus termination, this target-specific enhancement in visual cortex was specifically associated with correct conscious report. The strength of this modulation predicted individual levels of performance in behavior. By contrast, although later postcues presented 1000 msec after stimulus termination had some impact on activity in early visual cortex, this modulation no longer related to conscious report. These results demonstrate that within a critical time window of a few hundred milliseconds after a visual stimulus has disappeared, successful conscious report of that stimulus still relates to the strength of top-down modulation in early visual cortex. We suggest that, within this critical time window, sensory representation of a visual stimulus is still under construction and so can still be flexibly influenced by top-down modulatory processes.
Transcranial magnetic stimulation (TMS) is increasingly used to perturb targeted human brain sites non-invasively, to test for causal effects on performance of cognitive tasks. TMS might also be used in non-human primates to complement invasive work and compare with human studies. Here, we targeted the frontal eye fields (FEF) in two macaques with a continuous theta-burst (cTBS) protocol, testing the impact on visually guided saccades. After unilateral cTBS over the FEF in either hemisphere, a small (mean 7 ms) but highly consistent decrease in saccadic reaction times (RTs) was observed. Lower latencies arose for saccades both contra- and ipsilateral to the stimulated FEF after cTBS. These results provide the first demonstration that TMS can be used to affect saccadic behavior in non-human primates. The unexpectedly bilateral impact on RTs may reflect an impact on 'fixation' neurons in the FEF and/or transcallosal modulation of both FEFs induced by unilateral cTBS. In either case, this study demonstrates a clear behavioral effect induced by TMS in awake behaving monkeys performing a cognitive task. This opens new opportunities for investigating the causal roles of targeted brain areas in behavior, for measuring physiological consequences of TMS in the primate brain, and ultimately for human-monkey comparisons.
Humans are noted for their capacity to over-ride self-interest in favor of normatively valued goals. We examined the neural circuitry that is causally involved in normative, fairness-related decisions by generating a temporarily diminished capacity for costly normative behavior, a 'deviant' case, through non-invasive brain stimulation (repetitive transcranial magnetic stimulation) and compared normal subjects' functional magnetic resonance imaging signals with those of the deviant subjects. When fairness and economic self-interest were in conflict, normal subjects (who make costly normative decisions at a much higher frequency) displayed significantly higher activity in, and connectivity between, the right dorsolateral prefrontal cortex (DLPFC) and the posterior ventromedial prefrontal cortex (pVMPFC). In contrast, when there was no conflict between fairness and economic self-interest, both types of subjects displayed identical neural patterns and behaved identically. These findings suggest that a parsimonious prefrontal network, the activation of right DLPFC and pVMPFC, and the connectivity between them, facilitates subjects' willingness to incur the cost of normative decisions.
