@techreport{CaliendoGoethnerWeissenberger2019, type = {Working Paper}, author = {Caliendo, Marco and Goethner, Maximilian and Weißenberger, Martin}, title = {Entrepreneurial Persistence Beyond Survival: Measurement and Determinants}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {11}, issn = {2628-653X}, doi = {10.25932/publishup-43456}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-434563}, year = {2019}, abstract = {Entrepreneurial persistence is demonstrated by an entrepreneur's continued positive maintenance of entrepreneurial motivation and constantly-renewed active engagement in a new business venture despite counter forces or enticing alternatives. It is thus a crucial factor for entrepreneurs when pursuing and exploiting their business opportunities and to realize potential economic gains and benefits. Using rich data on a representative sample of German business founders, we investigate the determinants of entrepreneurial persistence. Next to observed survival we also construct a hybrid persistence measure capturing also the motivational dimension of persistence. We analyze the influence of individual-level (human capital and personality) and business-related characteristics on both measures as well as their relative importance. We find that the two indicators emphasize different aspects of persistence. For the survival indicator, the predictive power is concentrated in business characteristics and human capital, while for hybrid persistence, the dominant factors are business characteristics and personality. Finally, we show that results are heterogeneous across subgroups. In particular, formerly-unemployed founders do not differ in survival chances, but they are more likely to lack a high psychological commitment to their business ventures.}, language = {en} } @techreport{CaliendoKuennWeissenberger2019, type = {Working Paper}, author = {Caliendo, Marco and K{\"u}nn, Steffen and Weißenberger, Martin}, title = {Catching up or Lagging Behind?}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {12}, issn = {2628-653X}, doi = {10.25932/publishup-43701}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437012}, year = {2019}, abstract = {From an active labor market policy perspective, start-up subsidies for unemployed individuals are very effective in improving long-term labor market outcomes for participants. From a business perspective, however, the assessment of these public programs is less clear since they might attract individuals with low entrepreneurial abilities and produce businesses with low survival rates and little contribution to job creation, economic growth, and innovation. In this paper, we use a rich data set to compare participants of a German start-up subsidy program for unemployed individuals to a group of regular founders who started from nonunemployment and did not receive the subsidy. The data allows us to analyze their business performance up until 40 months after business formation. We find that formerly subsidized founders lag behind not only in survival and job creation, but especially also in innovation activities. The gaps in these business outcomes are relatively constant or even widening over time. Hence, we do not see any indication of catching up in the longer run. While the gap in survival can be entirely explained by initial differences in observable start-up characteristics, the gap in business development remains and seems to be the result of restricted access to capital as well as differential business strategies and dynamics. Considering these conflicting results for the assessment of the subsidy program from an ALMP and business perspective, policy makers need to carefully weigh the costs and benefits of such a strategy to find the right policy mix.}, language = {en} } @techreport{BruttelFelgendreherGuethetal.2019, type = {Working Paper}, author = {Bruttel, Lisa Verena and Felgendreher, Simon and G{\"u}th, Werner and Hertwig, Ralph}, title = {Strategic ignorance in repeated prisoners' dilemma experiments and its effects on the dynamics of voluntary cooperation}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {10}, issn = {2628-653X}, doi = {10.25932/publishup-43188}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-431881}, pages = {30}, year = {2019}, abstract = {Being ignorant of key aspects of a strategic interaction can represent an advantage rather than a handicap. We study one particular context in which ignorance can be beneficial: iterated strategic interactions in which voluntary cooperation may be sustained into the final round if players voluntarily forego knowledge about the time horizon. We experimentally examine this option to remain ignorant about the time horizon in a finitely repeated two-person prisoners' dilemma game. We confirm that pairs without horizon knowledge avoid the drop in cooperation that otherwise occurs toward the end of the game. However, this effect is superposed by cooperation declining more rapidly in pairs without horizon knowledge during the middle phase of the game, especially if players do not know that the other player also wanted to remain ignorant of the time horizon.}, language = {en} } @techreport{CaliendoTuebbicke2019, type = {Working Paper}, author = {Caliendo, Marco and T{\"u}bbicke, Stefan}, title = {New Evidence on Long-Term Effects of Start-Up Subsidies}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {6}, issn = {2628-653X}, doi = {10.25932/publishup-42679}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426798}, pages = {41}, year = {2019}, abstract = {The German start-up subsidy (SUS) program for the unemployed has recently undergone a major make-over, altering its institutional setup, adding an additional layer of selection and leading to ambiguous predictions of the program's effectiveness. Using propensity score matching (PSM) as our main empirical approach, we provide estimates of long-term effects of the post-reform subsidy on individual employment prospects and labor market earnings up to 40 months after entering the program. Our results suggest large and persistent long-term effects of the subsidy on employment probabilities and net earned income. These effects are larger than what was estimated for the pre-reform program. Extensive sensitivity analyses within the standard PSM framework reveal that the results are robust to different choices regarding the implementation of the weighting procedure and also with respect to deviations from the conditional independence assumption. As a further assessment of the results' sensitivity, we go beyond the standard selection-on-observables approach and employ an instrumental variable setup using regional variation in the likelihood of receiving treatment. Here, we exploit the fact that the reform increased the discretionary power of local employment agencies in allocating active labor market policy funds, allowing us to obtain a measure of local preferences for SUS as the program of choice. The results based on this approach give rise to similar estimates. Thus, our results indicating that SUS are still an effective active labor market program after the reform do not appear to be driven by "hidden bias".}, language = {en} } @techreport{BruttelStolleyUtikal2019, type = {Working Paper}, author = {Bruttel, Lisa Verena and Stolley, Florian and Utikal, Verena}, title = {Getting a Yes}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {2}, issn = {2628-653X}, doi = {10.25932/publishup-42763}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427638}, year = {2019}, abstract = {This paper studies how the request for a favor has to be devised in order to maximize its chance of success. We present results from a mini-dictator game, in which the recipient can send a free-form text message to the dictator before the latter decides. We find that putting effort into the message, writing in a humorous way and mentioning reasons why the money is needed pays off. Additionally, we find differences in the behavior of male and female dictators. Only men react positively to efficiency arguments, while only women react to messages that emphasize the dictator's power and responsibility.}, language = {en} } @techreport{Bruttel2019, type = {Working Paper}, author = {Bruttel, Lisa Verena}, title = {Is There a Loyalty-Enhancing Effect of Retroactive Price-Reduction Schemes?}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {5}, issn = {2628-653X}, doi = {10.25932/publishup-42768}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427688}, pages = {25}, year = {2019}, abstract = {This paper presents an experiment on the effect of retroactive price-reduction schemes on buyers' repeated purchase decisions. Such schemes promise buyers a reduced price for all units that are bought in a certain time frame if the total quantity that is purchased passes a given threshold. This study finds a loyalty-enhancing effect of retroactive price-reduction schemes only if the buyers ex-ante expected that entering into the scheme would maximize their monetary gain, but later learn that they should leave the scheme. Furthermore, the effect crucially hinges on the framing of the price reduction.}, language = {en} } @techreport{BruttelNithammerStolley2019, type = {Working Paper}, author = {Bruttel, Lisa Verena and Nithammer, Juri and Stolley, Florian}, title = {"Thanks in Advance"}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {7}, issn = {2628-653X}, doi = {10.25932/publishup-42770}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427706}, pages = {18}, year = {2019}, abstract = {This paper studies the effect of the commonly used phrase "thanks in advance" on compliance with a small request. In a controlled laboratory experiment we ask participants to give a detailed answer to an open question. The treatment variable is whether or not they see the phrase "thanks in advance." Our participants react to the treatment by exerting less effort in answering the request even though they perceive the phrase as polite.}, language = {en} } @techreport{MuellerNeumannWrohlich2019, type = {Working Paper}, author = {M{\"u}ller, Kai-Uwe and Neumann, Michael and Wrohlich, Katharina}, title = {Labor supply under participation and hours constraints}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {3}, issn = {2628-653X}, doi = {10.25932/publishup-42765}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427656}, pages = {50}, year = {2019}, abstract = {The paper extends a static discrete-choice labor supply model by adding participation and hours constraints. We identify restrictions by survey information on the eligibility and search activities of individuals as well as actual and desired hours. This provides for a more robust identification of preferences and constraints. Both, preferences and restrictions are allowed to vary by and are related through observed and unobserved characteristics. We distinguish various restrictions mechanisms: labor demand rationing, working hours norms varying across occupations, and insufficient public childcare on the supply side of the market. The effect of these mechanisms is simulated by relaxing different constraints at a time. We apply the empirical frame- work to evaluate an in-work benefit for low-paid parents in the German institutional context. The benefit is supposed to increase work incentives for secondary earners. Based on the structural model we are able to disentangle behavioral reactions into the pure incentive effect and the limiting impact of constraints at the intensive and extensive margin. We find that the in-work benefit for parents substantially increases working hours of mothers of young children, especially when they have a low education. Simulating the effects of restrictions shows their substantial impact on employment of mothers with young children.}, language = {en} } @techreport{BorckSchrauth2019, type = {Working Paper}, author = {Borck, Rainald and Schrauth, Philipp}, title = {Population density and urban air quality}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {8}, issn = {2628-653X}, doi = {10.25932/publishup-42771}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427719}, pages = {53}, year = {2019}, abstract = {We use panel data from Germany to analyze the effect of population density on urban air pollution (nitrogen oxides, particulate matter and ozone). To address unobserved heterogeneity and omitted variables, we present long difference/fixed effects estimates and instrumental variables estimates, using historical population and soil quality as instruments. Our preferred estimates imply that a one-standard deviation increase in population density increases air pollution by 3-12\%.}, language = {en} } @techreport{CaliendoTuebbicke2019, type = {Working Paper}, author = {Caliendo, Marco and T{\"u}bbicke, Stefan}, title = {Do Start-Up Subsidies for the Unemployed Affect Participants' Well-Being?}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {14}, issn = {2628-653X}, doi = {10.25932/publishup-43746}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437468}, pages = {47}, year = {2019}, abstract = {We estimate the long-term effects of start-up subsidies (SUS) for the unemployed on subjective outcome indicators of well-being, as measured by the participants' satisfaction in different domains. This extends previous analyses of the current German SUS program ("Gr{\"u}ndungszuschuss") that focused on objective outcomes - such as employment and income - and allows us to make a more complete judgment about the overall effects of SUS at the individual level. This is especially important because subsidizing the transition into self-employment may have unintended adverse effects on participants' well-being due to its risky nature and lower social security protection, especially in the long run. Having access to linked administrative-survey data providing us with rich information on pre-treatment characteristics, we base our analysis on the conditional independence assumption and use propensity score matching to estimate causal effects within the potential outcomes framework. We find long-term positive effects on job satisfaction but negative effects on individuals' satisfaction with their social security situation. Further findings suggest that the negative effect on satisfaction with social security may be driven by negative effects on unemployment and retirement insurance coverage. Our heterogeneity analysis reveals substantial variation in effects across gender, age groups and skill levels. The sensitivity analyses show that these findings are highly robust.}, language = {en} } @techreport{MuellerWrohlich2019, type = {Working Paper}, author = {M{\"u}ller, Kai-Uwe and Wrohlich, Katharina}, title = {Does subsidized care for toddlers increase maternal labor supply?}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {9}, issn = {2628-653X}, doi = {10.25932/publishup-42772}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427727}, pages = {50}, year = {2019}, abstract = {Expanding public or publicly subsidized childcare has been a top social policy priority in many industrialized countries. It is supposed to increase fertility, promote children's development and enhance mothers' labor market attachment. In this paper, we analyze the causal effect of one of the largest expansions of subsidized childcare for children up to three years among industrialized countries on the employment of mothers in Germany. Identification is based on spatial and temporal variation in the expansion of publicly subsidized childcare triggered by two comprehensive childcare policy reforms. The empirical analysis is based on the German Microcensus that is matched to county level data on childcare availability. Based on our preferred specification which includes time and county fixed effects we find that an increase in childcare slots by one percentage point increases mothers' labor market participation rate by 0.2 percentage points. The overall increase in employment is explained by the rise in part-time employment with relatively long hours (20-35 hours per week). We do not find a change in full-time employment or lower part-time employment that is causally related to the childcare expansion. The effect is almost entirely driven by mothers with medium-level qualifications. Mothers with low education levels do not profit from this reform calling for a stronger policy focus on particularly disadvantaged groups in coming years.}, language = {en} } @techreport{CaliendoSchroederWittbrodt2019, type = {Working Paper}, author = {Caliendo, Marco and Schr{\"o}der, Carsten and Wittbrodt, Linda}, title = {The Causal Effects of the Minimum Wage Introduction in Germany}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {1}, issn = {2628-653X}, doi = {10.25932/publishup-42692}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426929}, year = {2019}, abstract = {In 2015, Germany introduced a statutory hourly minimum wage that was not only universally binding but also set at a relatively high level. We discuss the short-run effects of this new minimum wage on a wide set of socio-economic outcomes, such as employment and working hours, earnings and wage inequality, dependent and self-employment, as well as reservation wages and satisfaction. We also discuss difficulties in the implementation of the minimum wage and the measurement of its effects related to non-compliance and suitability of data sources. Two years after the minimum wage introduction, the following conclusions can be drawn: while hourly wages increased for low-wage earners, some small negative employment effects are also identifiable. The effects on aspired goals, such as poverty and inequality reduction, have not materialized in the short run. Instead, a tendency to reduce working hours is found, which alleviates the desired positive impact on monthly income. Additionally, the level of non-compliance was substantial in the short run, thus drawing attention to problems when implementing such a wide-reaching policy.}, language = {en} } @techreport{CaliendoFossenKritikos2019, type = {Working Paper}, author = {Caliendo, Marco and Fossen, Frank M. and Kritikos, Alexander}, title = {What Makes an Employer?}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {13}, issn = {2628-653X}, doi = {10.25932/publishup-43736}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437360}, year = {2019}, abstract = {As the policy debate on entrepreneurship increasingly centers on firm growth in terms of job creation, it is important to better understand which variables influence the first hiring decision and which ones influence the subsequent survival as an employer. Using the German Socio-economic Panel (SOEP), we analyze what role individual characteristics of entrepreneurs play in sustainable job creation. While human and social capital variables positively influence the hiring decision and the survival as an employer in the same direction, we show that none of the personality traits affect the two outcomes in the same way. Some traits are only relevant for survival as an employer but do not influence the hiring decision, other traits even unfold a revolving door effect, in the sense that employers tend to fail due to the same characteristics that positively influenced their hiring decision.}, language = {en} } @techreport{AudretschHafensteinKritikosetal.2019, type = {Working Paper}, author = {Audretsch, David B. and Hafenstein, Marian and Kritikos, Alexander and Schiersch, Alexander}, title = {Firm Size and Innovation in the Service Sector}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {4}, issn = {2628-653X}, doi = {10.25932/publishup-42767}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427670}, pages = {46}, year = {2019}, abstract = {A rich literature links knowledge inputs with innovative outputs. However, most of what is known is restricted to manufacturing. This paper analyzes whether the three aspects involving innovative activity - R\&D; innovative output; and productivity - hold for knowledge intensive services. Combining the models of Crepon et al. (1998) and of Ackerberg et al. (2015), allows for causal interpretation of the relationship between innovation output and labor productivity. We find that knowledge intensive services benefit from innovation activities in the sense that these activities causally increase their labor productivity. Moreover, the firm size advantage found for manufacturing in previous studies nearly disappears for knowledge intensive services.}, language = {en} } @techreport{GallegoGranadosWrohlich2020, type = {Working Paper}, author = {Gallego Granados, Patricia and Wrohlich, Katharina}, title = {Selection into Employment and the Gender Wage Gap across the Distribution and Over Time}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {15}, issn = {2628-653X}, doi = {10.25932/publishup-44169}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441691}, year = {2020}, abstract = {Using quantile regression methods, this paper analyses the gender wage gap across the wage distribution and over time (1990-2014), while controlling for changing sample selection into full-time employment. Our findings show that the selection-corrected gender wage gap is much larger than the one observed in the data, which is mainly due to large positive selection of women into full-time employment. However, we show that selection-corrected wages of male and female workers at the lower half of the distribution have moderately converged over time. The reason for this development have been changes in the composition of the male full-time employment force over time, which in spite of the rather constant male full-time employment rate, have given place to a small but rising selection bias in male observed wages. In the upper half of the wage distribution, however, neither the observed nor the selection-corrected gender wage gap has narrowed over time.}, language = {en} } @techreport{FrodermannWrohlichZucco2020, type = {Working Paper}, author = {Frodermann, Corinna and Wrohlich, Katharina and Zucco, Aline}, title = {Parental Leave Reform and Long-run Earnings of Mothers}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {16}, issn = {2628-653X}, doi = {10.25932/publishup-44318}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-443188}, pages = {44}, year = {2020}, abstract = {Paid parental leave schemes have been shown to increase women's employment rates but decrease their wages in case of extended leave durations. In view of these potential trade-offs, many countries are discussing the optimal design of parental leave policies. We analyze the impact of a major parental leave reform on mothers' long-term earnings. The 2007 German parental leave reform replaced a means-tested benefit with a more generous earnings-related benefit that is granted for a shorter period of time. Additionally, a "daddy quota" of two months was introduced. To identify the causal effect of this policy on long-run earnings of mothers, we use a difference-in-difference approach that compares labor market outcomes of mothers who gave birth just before and right after the reform and nets out seasonal effects by including the year before. Using administrative social security data, we confirm previous findings and show that the average duration of employment interruptions increased for high-income mothers. Nevertheless, we find a positive long-run effect on earnings for mothers in this group. This effect cannot be explained by changes in working hours, observed characteristics, changes in employer stability or fertility patterns. Descriptive evidence suggests that the stronger involvement of fathers, incentivized by the "daddy months", could have facilitated mothers' re-entry into the labor market and thereby increased earnings. For mothers with low prior-to-birth earnings, however, we do not find any beneficial labor market effects of this parental leave reform.}, language = {en} } @techreport{AndresBruttelFriedrichsen2020, type = {Working Paper}, author = {Andres, Maximilian and Bruttel, Lisa Verena and Friedrichsen, Jana}, title = {Choosing between explicit cartel formation and tacit collusion - An experiment}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {19}, issn = {2628-653X}, doi = {10.25932/publishup-47388}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-473885}, pages = {55}, year = {2020}, abstract = {Numerous studies investigate which sanctioning institutions prevent cartel formation but little is known as to how these sanctions work. We contribute to understanding the inner workings of cartels by studying experimentally the effect of sanctioning institutions on firms' communication. Using machine learning to organize the chat communication into topics, we find that firms are significantly less likely to communicate explicitly about price fixing when sanctioning institutions are present. At the same time, average prices are lower when communication is less explicit. A mediation analysis suggests that sanctions are effective in hindering cartel formation not only because they introduce a risk of being fined but also by reducing the prevalence of explicit price communication.}, language = {en} } @techreport{CaliendoHennecke2020, type = {Working Paper}, author = {Caliendo, Marco and Hennecke, Juliane}, title = {Drinking is Different!}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {18}, issn = {2628-653X}, doi = {10.25932/publishup-46979}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-469790}, year = {2020}, abstract = {Unhealthy behavior can be extremely costly from a micro- and macroeconomic perspective and exploring the determinants of such behavior is highly important from an economist's point of view. We examine whether locus of control (LOC) can explain alcohol consumption as an important domain of health behavior. LOC measures how much an individual believes that she is in control of the consequences of her own actions for her life's future outcomes. While earlier literature showed that an increasing internal LOC is associated with increased health-conscious behavior in domains such as smoking, exercise or diets, we find that drinking seems to be different. Using German panel data from the Socio-Economic Panel (SOEP) we find a significant positive effect of having an internal LOC on the probability of moderate and regular drinking. We suggest and discuss two likely mechanisms for this relationship and find interesting gender differences. While social investments play an important role for both men and women, risk perceptions are especially relevant for men.}, language = {en} } @techreport{CaliendoCobbClarkObstetal.2020, type = {Working Paper}, author = {Caliendo, Marco and Cobb-Clark, Deborah A. and Obst, Cosima and Uhlendorff, Arne}, title = {Risk Preferences and Training Investments}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {23}, issn = {2628-653X}, doi = {10.25932/publishup-48092}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-480927}, pages = {35}, year = {2020}, abstract = {We analyze workers' risk preferences and training investments. Our conceptual framework differentiates between the investment risk and insurance mechanisms underpinning training decisions. Investment risk leads risk-averse workers to train less; they undertake more training if it insures them against future losses. We use the German Socio-Economic Panel (SOEP) to demonstrate that risk affinity is associated with more training, implying that, on average, investment risks dominate the insurance benefits of training. Crucially, this relationship is evident only for general training; there is no relationship between risk attitudes and specific training. Thus, as expected, risk preferences matter more when skills are transferable - and workers have a vested interest in training outcomes - than when they are not. Finally, we provide evidence that the insurance benefits of training are concentrated among workers with uncertain employment relationships or limited access to public insurance schemes.}, language = {en} } @techreport{BruttelGuethNithammeretal.2020, type = {Working Paper}, author = {Bruttel, Lisa Verena and G{\"u}th, Werner and Nithammer, Juri and Orland, Andreas}, title = {Inefficient Cooperation under Stochastic and Strategic Uncertainty}, series = {CEPA Discussion Papers}, journal = {CEPA Discussion Papers}, number = {20}, issn = {2628-653X}, doi = {10.25932/publishup-47550}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-475500}, year = {2020}, abstract = {Stochastic uncertainty can cause difficult coordination problems that may hinder mutually beneficial cooperation. We propose a mechanism of ex-post voluntary transfers designed to circumvent these coordination problems and ask whether it can do so. To test this, we implement a controlled laboratory experiment based on a repeatedly played Ultimatum Game with a stochastic endowment. Contrary to our hypothesis, we find that allowing voluntary transfers does not entail an efficiency increase. We suggest and analyze two main reasons for this finding: First, the stochastic uncertainty forces proposers to accept high strategic uncertainty if they intend to cooperate by claiming a low amount (which many proposers do not). Second, many responders behave only incompletely conditionally cooperative by transferring too little (which hinders cooperation in future periods).}, language = {en} }