Wintersemester 2017/2018

18.10.2017Marina Schröder, Universität Köln


The Rocky Road to Gender Equality - Immediate Effects of Quotas on Performance, Sabotage, and Representation

We study the immediate effect of a quota on performance, sabotage, and representation of the different groups affected. In an experimental study, we vary whether a quota is implemented and whether it is justified or not. We find that unjustified quotas result in a decrease in the performance of affirmed types, an increase in sabotage activity targeted at affirmed types, and a reduction in help received by affirmed types. We do not find such negative effects when the implemented quota is justified. Our findings suggest that information about the justification of a quota crucially determines the success of this intervention.

25.10.2017Anja Steinbach, UDE

Stepgrandparent-Stepgrandchild Relationships. Emotional Closeness and Frequency of Contact in Childhood and Adulthood

The many years shared by family members of three generations today have in general a positive impact on grandparents’ relations with their grandchildren. However, high divorce and remarriage rates, which lead to nontraditional family forms such as stepfamilies, challenge these relations, as some family members leave and others join during the process of repartnering. This paper focuses on emotional closeness and frequency of contact between stepgrandparents and their stepgrandchildren in childhood and adulthood. Based on the German Ageing Survey (DEAS) from 2014, 7,710 grandparent-grandchild and 465 stepgrandparent-stepgrandchild dyads nested within 4,992 families are analyzed. Hierarchical linear regression results provide support for the assumption that stepgrandparents feel significantly less close to their stepgrandchildren than biological grandparents to their biological grandchildren independent of family members’ characteristics. In contrast, the differences between stepgrandparents and grandparents in the frequency of contact with their (step-)grandchildren disappear when family members’ characteristics are controlled.






08.11.2017Paul Heidhues, HHU

Browsing versus Studying Offers
We introduce a simple model of a market in which consumers must make tradeoffs between "browsing" more products superficially, and "studying" fewer products in detail. Each firm chooses two price components, a headline price and an additional price, and specifies conditions under which a consumer can avoid the additional price. Each consumer can either fully understand the offer of one firm (studying), or look at only the headline prices of two firms (browsing). In equilibrium, high-value consumers browse and pay the additional price, but low-value consumers study to avoid the additional price. Although high-value consumers pay higher total prices, the average price consumers pay is decreasing in the share of high-value consumers. This result is consistent with evidence that a number of essential products are more expensive in lower-income neighborhoods, and our model also helps explain why entry into such neighborhoods does not solve the problem. More importantly, our framework generates a novel and powerful competition-policy-based argument for regulating the additional price or other secondary product features. In contrast to existing arguments that such regulations may be ineffective or even distortionary, we show that they have a multiplier effect: because consumers do not need to worry about the regulated feature, they do more browsing, enhancing competition. In many situations, the increase in competition also increases efficiency, but we identify a class of situations in which there is a tradeoff between competition and efficiency.


15.11.2017Prof. Dr. Johann Hurink, Universität Twente, Eschede

Decentralized Energy Management: New Challenges for Operations Research

Our energy systems undergo a fundamental change. Where in the past the energy mainly was generated in large power plants using fossil fuels, in the future a large part of the generation will result from small plants in decentralized locations using uncontrollable renewable sources. This leads to a loss of control over a larger fraction of the generation. To be able to compensate for this loss in flexibility on the generation side, we have to create and use flexibility on the consumption side.
This has led to the concept of ‘Smart Grids’ and ‘Decentralized Energy Management’ is seen as a key element for these Smart Grids.
In this talk we first give an overview of the relevant developments in the Energy Supply Chain. Based on the changes we sketch possible concepts and methods for future control of these supply chains. Hereby Decentralized Energy Management is seen as one of the key elements. In a second part, we argue that new upcoming devices with inherent storage (like e.g. batteries or electric vehicles) offer large portions of flexibility and discus a range of scheduling problems that come up for these devices. For a few of these problems we sketch possible solution approaches.

22.11.2017fällt aus




13.12.2017Johannes Voget, Universität Mannheim

International Taxation and Productivity Effects of M&As

We investigate the effect of international differences in corporate taxation on the realization of productivity gains in M&A deals. We argue that tax differentials distort the efficient allocation of productive factors following an M&A and thus mitigate the resulting productivity improvement. Using firm-level data on inputs and outputs of production as well as on corporate M&As, we estimate that a 1 percentage point increase in the absolute tax differential between the locations of two merging firms reduces the subsequent total factor productivity gain by 4.5%. This effect is less pronounced when firms can use international profit shifting to attenuate effective differences in taxation. In a complementary analysis, we use an event study design and a fixed effects model to explore the timing of the response of productivity, as well as, labor and capital input to the tax rate differential after the merger separately for the acquirer and the target. We show that our findings are mainly driven by deals with targets residing in locations with a tax advantage with respect to the acquirer. In these transactions, tax differentials reduce the post-merger adjustment in the target firm and inhibit the full realization of productivity gains.
10.01.2018Alexander Koch, Universität Aarhus

Motivational Goal Bracketing: An Experiment

We study in an online, real-effort experiment how the bracketing of non-binding goals affects performance in a work-leisure self-control problem. We externally induce the goal bracket – daily goals or a weekly goal – and within that bracket let subjects set goals for how much they want to work over a one-week period. Our theoretical model predicts (i) that weekly goals create incentives to compensate for a lower than desired performance today with the promise to work harder tomorrow, whereas daily goals exclude such excuses; (ii) that subjects with daily goals set higher goals in aggregate and work harder than those with weekly goals. Our data support these predictions. Surprisingly, however, when goals are combined with an externally enforced commitment that requires subjects to spend less than a minute each day on the task to get started working, performance deteriorates because of high dropout rates from the task.
17.01.2018Arnoud den Boer, Vrije Universiteit Amsterdam

Continuous assortment optimization

Assortment optimization is the problem of determining which products a seller should make available for sale to potential customers, in order to maximize her expected profit. This problem is found in many practical applications, e.g. hotel and airline revenue management, price and assortment optimization for online retailers, online advertisements optimization, optimal product design, and various facility location problems. In the recent operations research and management science literature, much attention goes to discrete assortment problems, where the decision maker can select from a finite number of products. This usually gives rise to computationally complex combinatorial problems, which can only be solved heuristically. In contrast, we turn our attention to continuous assortment problems, where the decision maker selects from a continuum of products. This is motivated from certain practical applications, but also as an alternative approach to large-scale discrete problems.
To give a flavor of the richness of this problem class, we consider two problems in detail.  In the first, the seller selects as assortment a subset of the unit interval, and customers make a purchase from this set according to a continuous multinomial-logit model. We discuss optimization and estimation aspects of this problem, and its relation to the well-studied discrete version. The second problem we discuss is assortment optimization for vertically differentiated products, where customers have minimum quality requirements and (therefore) non-continuous utility functions. We discuss the structure of the optimal assortment, computational aspects, and its relation to the product-design question in which pre-packed quantities a  product should be made available for sale.


24.01.2018Dr. Justus Arne Schwarz, Universität Mannheim

Sales and operations planning for product rollovers

The successful introduction of new products to the market is a key driver for the financial success of companies. A product rollover takes place when a product generation is replaced by its successor. The key decisions are pricing and the offered amount of each product generation as well as the timing of the introduction to and the withdrawal from the market. If the production of the old generation is stopped prior to its withdrawal from the market, an inventory decision has to be made additionally.  In contrast to the existing literature, we consider finite production capacities. These can be found in practice if new technologies are used in the production process or the old and new product share the same capacity. We propose a two-period setting with a vertical demand model to capture effects of product based and stock-out based substitution effects. A numerical analysis demonstrates the impact of limited production capacity on the optimal rollover decisions. Directions for future research are outlined.

31.01.2018Robert Böhm, RWTH Aachen

Understanding and promoting vaccine uptake using behavioral experiments

Vaccination is one of the most effective preventive methods available in medicine. Despite their great success in the past, vaccine hesitancy is an increasing problem in Western societies. This may undermine the collective benefits of herd immunity, i.e., the indirect protection of other, non-vaccinated individuals. In this overview talk, I will present a decision making model describing the direct and indirect effects of vaccination and their consequences for the individual incentives to vaccinate. I will show both theoretically and experimentally -- using an interactive vaccination game -- that individuals have an incentive to free-ride on others indirect protection with increasing vaccination rates. Furthermore, I will show that communicating the concept of herd immunity increases vaccine uptake due to increasing prosocial vaccine uptake. Lastly, I will discuss several policy interventions to increase vaccine uptake (e.g., vaccination recommendations, mandatory vaccination) and provide experimental evidence regarding their potential advantages and drawbacks.