Browsing by Subject "Selection"

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Economic problems of health insurance : reforms and competition
(2016) Lange, Renate; Schiller, Jörg
Although most modern societies agree that everyone should receive adequate access to medical treatment, health care systems worldwide vary greatly in terms of financing of health care costs, the provision of medical services, and regulatory aspects. Rising costs, economic downturns, and the demographic development have embraced the call for change particularly with regard to financing of health care costs and access to health insurance. Most health care systems have developed historically, but underwent fundamental changes as a consequence of policy decisions and reforms. Looking back on recent health reforms in the U.S. and Germany two divergent trends can be observed: Over the last two decades, German Statutory Health Insurance (SHI) primarily experienced benefit cuts and had to implement economic incentives and market-based instruments to a solidary-based social security model in order to overall contain costs. At the same time, recent health reforms in the U.S. have shown that a solely market-based health insurance system is hardly consistent with modern society’s ideas on fairness and distributive justice. Furthermore, the exclusion of large parts of the population from seeking health insurance as a result of high premiums is not only associated with high costs and negative effects (even for those holding insurance coverage), but overall seen as highly inefficient. This thesis aims to draw a comprehensive picture of economic problems of health insurance and, thereby, assesses economic goals and analyzes effects of recent health reforms in the two historically grown very different health insurance systems of Germany and the U.S. More specifically, three research questions will be addressed: First, looking at the demand for supplemental health insurance (SuppHI) in the aftermath of benefit reductions in German SHI, it investigates what factors drive the demand for SuppHI and what are possible sources of selection. Furthermore, this thesis offers new insights on what the two health insurance systems can learn and take over from each other. In this context, it discusses how new trends in health insurance in the U.S. (i.e. Health Savings Accounts (HSAs)) could be implemented in German SHI. The third focus of this thesis is on the mutual interdependence of public and private health insurance markets. Analyzing financial data of private health insurers in the U.S., it looks into the question of how premiums in Private Health Insurance (PHI) are affected by public health insurance programs (i.e. Medicaid).
Genomic selection in synthetic populations
(2017) Müller, Dominik; Melchinger, Albrecht E.
The foundation of genomic selection has been laid at the beginning of this century. Since then, it has developed into a very active field of research. Although it has originally been developed in dairy cattle breeding, it rapidly attracted the attention of the plant breeding community and has, by now (2017), developed into an integral component of the breeding armamentarium of international companies. Despite its practical success, there are numerous open questions that are highly important to plant breeders. The recent development of large-scale and cost-efficient genotyping platforms was the prerequisite for the rise of genomic selection. Its functional principle is based on information shared between individuals. Genetic similarities between individuals are assessed by the use of genomic fingerprints. These similarities provide information beyond mere family relationships and allow for pooling information from phenotypic data. In practice, first a training set of phenotyped individuals has to be established and is then used to calibrate a statistical model. The model is then used to derive predictions of the genomic values for individuals lacking phenotypic information. Using these predictions can save time by accelerating the breeding program and cost by reducing resources spent for phenotyping. A large body of literature has been devoted to investigate the accuracy of genomic selection for unphenotyped individuals. However, training individuals are themselves often times selection candidates in plant breeding, and there is no conceptual obstacle to apply genomic selection to them, making use of information obtained via marker-based similarities. It is therefore also highly important to assess prediction accuracy and possibilities for its improvement in the training set. Our results demonstrated that it is possible to increase accuracy in the training set by shrinkage estimation of marker-based relationships to reduce the associated noise. The success of this approach depends on the marker density and the population structure. The potential is largest for broad-based populations and under a low marker density. Synthetic populations are produced by intermating a small number of parental components, and they have played an important role in the history of plant breeding for improving germplasm pools through recurrent selection as well as for actual varieties and research on quantitative genetics. The properties of genomic selection have so far not been assessed in synthetics. Moreover, synthetics are an ideal population type to assess the relative importance of three factors by which markers provide information about the state of alleles at QTL, namely (i) pedigree relationships, (ii) co-segregation and (ii) LD in the source germplasm. Our results show that the number of parents is a crucial factor for prediction accuracy. For a very small number of parents, prediction accuracy in a single cycle is highest and mainly determined by co-segregation between markers and QTL, whereas prediction accuracy is reduced for a larger number of parents, where the main source of information is LD within the source germplasm of the parents. Across multiple selection cycles, information from pedigree relationships rapidly vanishes, while co-segregation and ancestral LD are a stable source of information. Long-term genetic gain of genomic selection in synthetics is relatively unaffected by the number of parents, because information from co-segregation and from ancestral LD compensate for each other. Altogether, our results provide an important contribution to a better understanding of the factors underlying genomic selection, and in which cases it works and what information contributes to prediction accuracy.
Occupational licensing and the gender wage gap
(2020) Rostam-Afschar, Davud; Pagliero, Mario; Koumenta, Maria
We use a unique survey of the EU labor force to investigate the relationship between occupational licensing and the gender wage gap. We find that the gender wage gap is canceled for licensed self-employed workers. However, this closure of the gender wage gap is not mirrored by significant changes in the gender gap inhours worked. Our results are robust using decomposition methods, quantile regressions, different datasets, and selection correction.
Strategies for selecting high-yielding and broadly adapted maize hybrids for the target environment in Eastern and Southern Africa
(2012) Windhausen, Sandra Vanessa; Melchinger, Albrecht E.
Maize is a major food crop in Africa and primarily grown by small-holder farmers under rain-fed conditions with low fertilizer input. Projections of decreasing precipitation and increasing fertilizer prices accentuate the need to provide farmers with maize varieties tolerant to random abiotic stress, especially drought and N deficiency. Genetic improvement for the target environment in Eastern and Southern Africa can be achieved by: (i) direct selection of grain yield in random abiotic stress environments, (ii) indirect selection for a secondary trait or grain yield in optimal, low-N and/or managed stress environments, or (iii) index selection using information from all test environments. At present, the maize hybrid testing programs of the International Maize and Wheat Improvement Center (CIMMYT) select primarily for grain yield under managed stress and optimal environments and subdivide the target environment according to geographic and climatic differences. It is not known to what extend the current strategy contributes to selection gains. The same holds true for genomic prediction, a strategy that is not yet implemented into the CIMMYT maize breeding program but that may accelerate breeding progress and reduce cycle length by predicting genotype performance based on molecular markers. Regarding the different strategies mentioned for selecting high-yielding and broadly adapted maize hybrids, the breeder needs to decide which of them are most promising to increase genetic gains. Consequently, the objectives of my thesis were to (1) evaluate the potential of leaf and canopy spectral reflectance as novel secondary traits to predict grain yield across different environments, (2) estimate to what extent indirect selection in managed drought and low-N stress environments is predictive of grain yield in random abiotic stress environments, (3) investigate whether subdividing the target environment into climate, altitude, geographic, yield level or country subregions is likely to increase rates of genetic gain, and (4) evaluate the prospects of genomic prediction in the presence of population structure. The measurement of spectral reflectance (495 ? 1853 nm) of both leaves and canopy at anthesis and milk grain stage explained less than 40% of the genetic variation in grain yield after validation. Consequently, selection based on predicted grain yield is only suitable for pre-screening, while final yield evaluation will still be necessary. Nevertheless, the prospect of developing inexpensive and easy to handle devices that can provide, at anthesis, precise estimates of final grain yield warrants further research. Based on a retrospective analysis across 9 years, more than 600 trials and 448 maize hybrids, it was shown that maize hybrids were broadly adapted to climate, altitude, geographic and country subregions in Eastern and Southern Africa. Consequently, I recommend that the maize breeding programs of CIMMYT in the region should be consolidated. Within the consolidated breeding programs, genotypes should be selected for performance in low- and high yielding environments as the genotype-by-yield level interaction variance was high relative to the genetic variance and genetic correlations between low- and high-yielding environments were moderate. Genetic gains were maximized by index selection, considering the yield-level effect as fixed and appropriately weighting information from all trials. To allow better allocation of resources, locations with high occurrence of random abiotic stress need to be identified. Heritability in trials conducted at these locations may be increased by the use of row- and column designs and/or spatial adjustment. Furthermore, resources invested into managed drought trials should be maintained during early breeding stages but shifted to the conduct of low-N trials at later breeding stages. Investments in a larger number of low-N trials may increase selection gain, because performance under low-N and random abiotic stress was highly correlated and genotypes can be easily selected under different levels of soil N. Prospects are promising to accelerate breeding cycles by the use of genomic prediction. Based on two large data sets on the performance of eight breeding populations, it was shown that prediction accuracy resulted primarily from differences in mean performance of these populations. Genomic prediction may be implemented into the CIMMYT maize breeding program to predict the performance of lines from a diversity panel, segregating lines from the same or related crosses, and progenies from closed populations within a recurrent selection program. The breeding scenarios in which genomic prediction is most promising still need to be defined. Generally, the construction of larger training sets with strong relationship to the validation set and a detailed analysis of the population structure within the training and validation sets are required. In conclusion, combining index and genomic selection is the most promising strategy for providing high-yielding and broadly adapted maize genotypes for the target environments in Eastern and Southern Africa.
The economics of elderly care
(2015) Bauer, Jan Michael; Sousa-Poza, Alfonso
Longer life expectancy and low fertility rates increase the share of elderly among the population of most industrialized countries. This demographic change affects the economy and the society and is most likely to proceed in the future. Therefore, policy makers and families need to be aware of the implications associated with an aging population. One particularly great challenge comes with the rising number of fragile elderly people, for which most countries are currently unable to provide sufficient care solutions. Germany, for instance, is facing a constantly rising share of people in need that mostly receive informal care from friends and family. Public support promotes these informal care arrangements (§3 SGB XI) and endorses care receivers to remain in their domestic environment. Even though such informal care arrangements are preferred by most families, caregiving can have a large impact on the caregiver’s life. Policy makers need to measure and incorporate these outcomes in order to provide suitable aid for caring families and, thereby, ensuring sustainable and dignified population aging. This dissertation consists of three academic papers and contributes to the topic in several ways: the first paper reviews the recent literature on the effects of informal caregiving on the caregiver and, thereby, assesses the opportunity costs associated with informal care provision. Further, we evaluated the methodology that is commonly used and identify certain risk groups as well as arrangements that are particularly burdensome. The second paper takes a specific look at the subjective well-being of caregivers in Germany and analyzes effects associated with providing care. In contrast to most prior studies, the paper uses large population-based longitudinal data, accounts for unobserved heterogeneity, and estimates the relationship with different methodologies. The paper further values well-being losses monetarily, which allows a comparison to formal care alternatives. The third paper provides new insights on individual selection behavior in the market for supplemental health insurances. This is an increasingly popular way to insure against long-term care needs, a risk not fully covered despite a statutory long-term care insurance. Private insurance markets are fragile in the presences of asymmetric information and, therefore, might not be a sustainable solution to cover the increasing risks of an aging society. We developed an innovative approach to disentangle different selection behaviors in a heterogeneous sample and identify asymmetric information exemplarily for the market of supplemental dental insurance, despite no risk-coverage correlation for the aggregated sample.
Untersuchungen zu Einfachgebrauchskreuzungen beim Merinolandschaf
(2013) Henseler, Stefanie; Bennewitz, Jörn
The present study examined the meat and carcase quality of lambs slaughtered in the German federal state of Baden-Württemberg in order to determine the sire breeds most suitable for the Merinolandschaf, a Merino land race. For this purpose, rams of the meat breeds Charollais, Ile de France, Blackheaded sheep, Suffolk and Texel were bred to the widespread Merinolandschaf in order to produce cross bred lambs. In addition, rams of the Merinolandschaf were used to produce purebred lambs. The lambs were raised on seven farms, then fattened at one farm and slaughtered. 1600 lambs were used to evaluate meat quality, fattening performance and yield at slaughter. 105 animals were chosen from a total of 1600 lambs used in the study. These were tasted by a panel consisting of 21 persons. Results of this sensory analysis were combined with results in regard to fattening performance, yield at slaughter and quality of meat in a joint index. The net gain from fattening of the Texel sheep surpassed all other crossbreeds. In regard to yield from slaughter, crossbreeds with Charollais, Ile de France and Texel showed improvement in development of haunches and classification. Texel crossbreed ranked highest in respect to meat area of the chops. The parameters determining the quality of the meat – drip loss and loss by cooking – were lowest for pure Merinolandschaf. High shear force was necessary for meat of Suffolk and Texel crossbreeds, whereas Charollais crossbreed showed the lowest value for this parameter. The sensory analysis showed that crossbreeds with Charollais, Blackhead sheep and Suffolk as well as the pure breed Merinolandschaf are well suited to production of high-quality lamb‘s meat. In addition, it was shown that lamb’s meat from the German federal state of Baden-Württemberg differs significantly from lamb’s meat from New Zealand. There is a significant negative correlation between shear force according to Warner-Bratzler and the perceived tenderness of meat. The joint index consists of 10 economically relevant parameters, relatively weighted according to economic factors. The first rank was achieved by the crossbreed with Ile de France, followed by Texel, Suffolk and Blackhead sheep. To choose the optimal rams, i.e. the optimal sire breed, under practical circumstances, it is vital to take the conditions of the individual farm – such as marketing strategies – into consideration. With different weighting of single traits ranking of breeds can differ.