Imbens and Angrist (1994) were the first to exploit a monotonicity condition in order to identify... more Imbens and Angrist (1994) were the first to exploit a monotonicity condition in order to identify a local average treatment effect parameter using instrumental variables. More recently, Heckman and Vytlacil (1999) suggested the estimation of a variety of treatment effect parameters using a local version of their approach. We investigate the sensitivity of the respective estimates to random departures from monotonicity. Approximations to the respective bias terms are derived.
Abstract: Pricing pressure indices have recently been proposed as alternative screening devices f... more Abstract: Pricing pressure indices have recently been proposed as alternative screening devices for horizontal mergers involving differentiated products. We extend the concept of Upward Pricing Pressure (UPP) proposed by Farrell and Shapiro (2010) to two-sided markets. Examples of such markets are the newspaper market, where the demand for advertising is related to the number of readers, and the market for online search, where advertising demand depends on the number of users.
Abstract This paper deals with hyperbolic discounting in a macro context. Time consistency is dis... more Abstract This paper deals with hyperbolic discounting in a macro context. Time consistency is discussed in terms of rational behavior and rational expectations. The theory is applied to the intertemporal consumption decision in order to explain undersaving in an economy. Moreover, possible implications on policy makers' decisions on reforms and budget deficits are evinced. Finally, the Ricardian equivalence theorem is shown to heavily rely on the assumption of time consistent choice.
Abstract: Feedback mechanisms that allow partners to rate each other after a transaction are cons... more Abstract: Feedback mechanisms that allow partners to rate each other after a transaction are considered crucial for the success of anonymous internet trading platforms. We document an asymmetry in the feedback behaviour on eBay, propose an explanation based on the micro structure of the feedback mechanism and the time when feedbacks are given, and support this explanation by findings from a large data set. Our analysis implies that the informational content of feedback records is likely to below.
First and foremost, I would like to thank my supervisors Enno Mammen and Konrad Stahl for their s... more First and foremost, I would like to thank my supervisors Enno Mammen and Konrad Stahl for their support and numerous insightful discussions. Furthermore, I am grateful to Andrew Chesher for his support and helpful suggestions during my stay at the University College London in the academic year 2003/4. Chapters 2 through 4 of this dissertation have been written over the last four years.
The effect of private health insurance on medical care utilization and self‐assessed health in Germany
Abstract In Germany, employees are generally obliged to participate in the public health insuranc... more Abstract In Germany, employees are generally obliged to participate in the public health insurance system, where coverage is universal, co-payments and deductibles are moderate, and premia are based on income. However, they may buy private insurance instead if their income exceeds the compulsory insurance threshold. Here, premia are based on age and health, individuals may choose to what extent they are covered, and deductibles and co-payments are common.
eBay's feedback mechanism is considered crucial to establishing and maintaining trust on the worl... more eBay's feedback mechanism is considered crucial to establishing and maintaining trust on the world's largest trading platform. Yet, there is confusion among users about its exact institutional details, which changed substantially in May 2007. Most importantly, buyers now have the possibility to leave additional, anonymous ratings on sellers on four different criteria. We provide a thorough description of the institutional details of eBay's feedback mechanism, including those changes.
Abstract We compare different methods to assess unilateral merger effects in a two-sided market b... more Abstract We compare different methods to assess unilateral merger effects in a two-sided market by applying them to a hypothetical merger in the Dutch newspaper industry. We first specify and estimate a structural model of demand for differentiated products in both the readership and the advertising sides of the market. This allows us to recover price elasticities and indirect network effects. Marginal costs are then recovered from an oligopoly model of the supply side.
Abstract The life cycle model predicts that individuals substitute leisure for consumption when t... more Abstract The life cycle model predicts that individuals substitute leisure for consumption when they retire. We show that the effect of retirement on various well-being measures available in the German Socio-Economic Panel (GSOEP) are compatible with this prediction: the overall effect on life satisfaction is negligible, while satisfaction with the free time increases and satisfaction with household income decreases.
Abstract We confront a representative sample of one 1,102 Dutch individuals with a series of ince... more Abstract We confront a representative sample of one 1,102 Dutch individuals with a series of incentivized investment decisions and also elicit their time preferences. There are two treatments that differ in the frequency at which indiviuals decide about the invested amount. The low frequency treatment stimulates decision makers to frame a sequence of risky decisions broadly rather than narrowly. We find that the framing effect is significantly larger for impatient than for patient individuals.
Abstract: We study a differentiated product market in which an investor initially owns a controll... more Abstract: We study a differentiated product market in which an investor initially owns a controlling stake in one of two competing firms and may acquire a non-controlling or a controlling stake in a competitor, either directly using her own assets, or indirectly via the controlled firm. While industry profits are maximized within a symmetric two product monopoly, the investor attains this only in exceptional cases. Instead, she sometimes acquires a non-controlling stake.
Summary. A regression of wages on firm tenure is likely to yield biased estimates of the returns ... more Summary. A regression of wages on firm tenure is likely to yield biased estimates of the returns to tenure because tenure and wages are confounded by unobserved attributes of the job and the unobserved quality of the match between the firm and the employee. Previously, the within-job variation in tenure has been used as an instrument to estimate the average returns to tenure. We propose to use instead an easy-to-implement control function estimator for the returns to tenure and their dependence on unobserved heterogeneity.
Abstract I outline a theory of choice in situations in which the decisionmaker is uncertain about... more Abstract I outline a theory of choice in situations in which the decisionmaker is uncertain about his preferences. One prediction of this theory is that his willingness to pay for a good is always lower than his valuation. The outcome of an experiment, a repeated sealed-bid second price auction, supports this finding.
Abstract This paper is inspired by the literature on procrastination in behavioral economics. I d... more Abstract This paper is inspired by the literature on procrastination in behavioral economics. I develop a general framework in order to define time consistent choice formally. The distinction between static and dynamic rationality is made and conditions are derived under which choice is time consistent.
Abstract Recent studies debate how the unobserved dependence between the monetary return to colle... more Abstract Recent studies debate how the unobserved dependence between the monetary return to college education and selection into college can be characterised. This paper examines this question using British data. We develop a semiparametric local instrumental variables estimator for identified features of a flexible correlated random coefficient model. These identified features are directly related to the marginal and average treatment effect in policy evaluation.
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Papers by Tobias Klein