Cumulative PhD Thesis, four essays: "Using a randomized field experiment, we show that health care specialists cream-skim patients by their expected profitability. In the German two-tier system, outpatient reimbursement rates for both public and private insurance are centrally determined but are significantly higher for the privately insured. In our field experiment, following a standardized protocol, the same hypothetical patient called 991 private practices in 36 German counties to schedule appointments for allergy tests, hearing tests and gastroscopies. Practices were 4% more likely to offer an appointment to the privately insured. Conditional on being offered an appointment, wait times for the publicly insured were twice as long than for the privately insured. We also find smaller access differences when reimbursement rate differences are smaller. Our findings show that structural differences in reimbursement rates lead to structural differences in health care access." "We study the regional distribution of primary care physicians in Germany to learn about the extent and possible reasons of geographic maldistribution. For this aim, we apply a greedy capacitated algorithm on very fine spatial data and calculate a reference allocation of primary care physicians. We compare this reference allocation to the status quo. Our results suggest that Germany has a shortage of primary care physicians of 6% which is particularly evident in rural areas. Some municipality characteristics like purchasing power and number of schools can explain parts of the difference in the number of physicians between cities and rural areas. Large parts, however, remain unexplained." "We investigate the short- and long-term effects of retirement on loneliness using panel data from the Survey of Health, Aging, and Retirement in Europe. To estimate causal effects, we exploit differences in retirement eligibility rules across and within countries and use retirement thresholds in an instrumental variable setting. On average, we find that entering retirement leads to a significant reduction in loneliness in the long run, although our results show no clear effect in the short run. The reduction is driven by individuals being less likely to feel socially isolated and lacking companionship. Our results suggest that individuals adapt to retirement by increasing their activity levels and reap the benefits in terms of reduced loneliness and social isolation. A heterogeneity analysis by gender reveals that retirement increases feelings of loneliness for women in the short term and that this effect seems to be driven by women lacking companionship when their partner is not yet retired." "Hypothetical bias is the discrepancy between stated preferences and actual choices. As such, it is one of the key issues regarding the use of hypothetical survey methods and therefore highly relevant for economists in understanding human behavior and refining policy interventions. Hypothetical survey methods are often used to inform our view on decision making in health and financial settings. However, there is limited understanding of the extent and underlying factors of hypothetical bias within the context of health insurance. This study contributes to this understanding and explores the extent of hypothetical bias and its correlation with personality traits and behavioral patterns in a health insurance setting. Using large-scale survey data in tandem with detailed information on health plans, I show that the majority of enrollees overestimate their willingness to switch health plans when facing a price increase: 64% show hypothetical bias. Especially conscientious, impulsive or negative reciprocal individuals are prone to hypothetical bias. In contrast, internal locus of control correlates with consistent preferences. These findings can help refine mitigation strategies and assess the reliability of stated preferences."

Ruhr-Universität Bochum