Este trabalho apresenta três extensões ao modelo de reputação proposto por Shapiro (1983). A primeira torna o modelo original mais adequado para avaliar o problema de informação assimétrica de bens de busca e bens credenciais, a segunda permite identificar o ganho de eficiência gerado pela inclusão de um sistema de informação adicional e, a terceira mostra que a provisão de um volume maior de informação pode gerar efeitos adversos quando o produto em questão possui vários atributos. Em seguida, os desenvolvimentos teóricos são utilizados para avaliar os efeitos da introdução do Exame Nacional de Cursos sobre o mercado de cursos superiores do Brasil. Algumas das predições do modelo são testadas empiricamente, fornecendo indicações de que este Exame possui um papel relevante para mitigar o problema de informação identificado neste mercado. / This essay presents three extensions to the model first proposed by Shapiro (1983) regarding reputation. The first extension adjusts Shapiro’s original model in order to make it more suitable in dealing with the problem of asymmetric information of search goods and credence goods. The second one allows the identification of the efficiency gains obtained after the inclusion of an additional information system, while the third extension demonstrates that additional information could generate adverse effects when the good under consideration has several attributes. These theoretical extensions are then applied to evaluate the effects of the Brazilian experience regarding the introduction of the Courses National Exam - Exame Nacional de Cursos – on Brazil’s market of undergraduate school courses. Some of the theoretical predictions of the model are empirically tested, offering indications that such exam plays a relevant role while diminishing the informational problem that characterizes this market.

L’aléa moral est une source de distorsion économique. La prédiction classique dans un cadre simple est qu’une meilleure couverture conduit à un effort moindre. Cette thèse étudie dans quelle mesure cette prédiction est ou non vérifiée empiriquement dans des cadres plus complexes. Le premier chapitre s’intéresse aux absences pour raison de santé. La politique étudiée est le jour de carence pour arrêt maladie dans la fonction publique de l’Etat en France. Cette politique de remboursement moins généreuse a notamment pour but de réduire l’absentéisme. Elle conduit à une baisse de la prévalence des absences de courte durée. Mais elle conduit aussi à une hausse de la prévalence des absences de longue durée. En conséquence, la prévalence de l’ensemble des absences pour raison de santé reste inchangée. Les deux chapitres suivants s’intéressent aux systèmes de bonus-malus d’un assureur automobile irlandais. Le deuxième chapitre s’intéresse à l’introduction d’un état très protecteur : la protection à vie du bonus. Cette protection est octroyée automatiquement et gratuitement aux assurés sous des conditions restrictives d’historique de sinistre et d’ancienneté. Comparé à la situation dans laquelle cet état protecteur n’existe pas, le taux de sinistre des assurés protégés augmente, tandis que le taux de sinistre des agents non protégés diminue, dans l’espoir d’être récompensés par la protection. L’existence de la protection est à l’origine d’un transfert intertemporel. Les assurés renoncent à de l’utilité présente en exerçant un effort supérieur, afin d’être récompensés par la protection et de profiter d’une utilité future plus élevée due à un effort moindre. Le troisième chapitre étudie la réaction juste après que l’assuré est récompensé par la protection à vie du bonus. Le taux de sinistre augmente immédiatement, mais seulement quand la protection existe depuis quelque temps. Cela suggère que l'effet d'un changement incitatif dépend de sa nature, mais aussi de son contexte. / Moral hazard is a source of economic distortion. The classical prediction in a simple framework is that a better coverage leads to a lower effort. This thesis studies the extent to which this prediction is empirically verified in more complex settings. The first chapter focuses on health-related absences. The policy under study is the one-day waiting period for sick leave in the French central civil service. This less generous reimbursement policy notably aims at reducing absenteeism. It leads to a decrease in the prevalence of short-term absences. But it also leads to an increase in the prevalence of long-term absences. As a result, the prevalence of all health-related absences stay unchanged. The two following chapters focus on bonus-malus systems used by an Irish car insurer. The second chapter focuses of the introduction on a highly protecting state: the lifetime bonus protection. This protection is granted automatically and freely to insurees under restrictive conditions on past claims and seniority. Compared to the situation in which this protecting state does not exist, the claims rate of protected insurees increases, but the claims rate of unprotected insurees decreases, in the hope of being rewarded with the protection. The existence of the protection induces an intertemporal transfer. Insurees waive present utility by exerting more effort, so as to be rewarded with the protection and to enjoy more future utility due to lower future effort. The third chapter studies the reaction just after the insuree is rewarded with the lifetime bonus protection. The claims rate increases immediately, but only when the protection exists for some time. This suggests that the effect of an incentive change depends on its nature, but also on its context.

The diploma thesis investigates causes and progression of the financial crisis beginning in 2007 in the United States and leading in the economic recession. Theoretical part of the thesis describes business cycles and their explanations in accordance with the Austrian theory of the business cycle and other theories. Analytical part of the thesis explores the period before the crisis and significant events relevant to it. The main subject of the thesis are institutions and regulatory measures that have major importance for the U.S. real estate market -- including monetary and intervenionist policy of Fed, Community Reinvestment Act, government sponsored enterprises and three major rating agencies. The goal of the work is to provide a comprehensive view of the financial crisis and analyse main factors that influenced its creation -- credit expansion, mortgage market, Fed's monetary policy, bank behavior, etc. This thesis tries to demonstrate an inaccuracy of state inteventions and their impacts on the economy and market system.

Les désastres naturels ont des conséquences particulièrement dévastatrices dans les pays en développement où les individus sont hautement vulnérables et les institutions inefficaces. Néanmoins, leurs impacts sur le bien être des ménages et le rôle des autorités publiques restent encore mal compris. En outre, alors que la plupart des études se focalisent sur le risque climatique, les désastres géologiques, et les éruptions volcaniques en particulier, restent peu étudiés. Pourtant, même si elles représentent une fraction marginale des désastres naturels au niveau mondial, les éruptions volcaniques sont une menace majeure dans certains pays tels que l’Indonésie ou l’Equateur. La présente thèse tente donc de contribuer à la littérature à travers trois essais empiriques traitant de l’effet à long terme du risque volcanique sur l’accumulation de capital des ménages, de l’impact d’une éruption sur le capital social ainsi que du rôle des autorités publiques dans les décisions de migration. / Natural disasters have particularly devastating consequences in developing countries where people are highly vulnerable and institutions remain inefficient. Nevertheless, their impacts on households’ well-being and the role of public authorities are, yet, not fully understood. In addition, while most studies focus on climatic risk, geological disasters, and volcanic eruptions in particular, are clearly understudied. However, despite representing a marginal share of natural disasters at the global level, volcanic eruptions are a major threat in some countries, such as Indonesia or Ecuador. The present dissertation tries to contribute to the literature by investigating the long-term effect of volcanic hazard on farmers’ capital accumulation, the impact of an eruption on social capital, as well as the potential mitigating role of public authorities on migration decisions.

企業併購的成敗，基本上應視其併購的策略性目標是否達成，然而策略性的目標往往只能從收購後整體的營運績效或投資收益來進行評估。事實上，企業併購即是一種投資活動，投資後的環境變化事先即難以掌握，如何有效的預防企業併購的風險問題，尤為進行併購規劃時重要的課題。本文嘗試以「代理問題」來解釋企業併購完成後的「雙方道德風險問題」，希望利用支付方式的財務規劃，有效的對企業併購完成後的道德風險作防範。 本文的主要目的在於，利用訊息理論中的代理模型（principal-agent model），研究企業併購雙方在「資訊不對稱」下，利用「雙方道德風險模型」（double-sided moral hazard model）的建立，規劃最適的支付方式設計，並對模型最適支付方式契約特性與影響因素作分析。設定企業併購的買方公司（the bidder）為所有人角色，目標公司（the target）為代理人角色，並且雙方公司皆為「風險趨避」的態度，以期望效用極大作為決策依據。買方公司基於「風險分散(risk- sharing)」與「契約誘因(incentives)」的考量，設計一種最適的「簡單線性支付方式」契約型態，綜合部分現金與部分股票支付的「混合性支付方式」，進行併購投資的要約行動。 模型的結果，買方公司所提出的最適目標公司持股比例，為雙方的風險趨避係數、公司價值的變異風險，以及雙方努力投入的成本係數所決定。並且進一步求出最適的努力水準，與最適現金支付金額，設計最適的股票與現金支付比例，以作為企業併購支付方式財務規劃的建議。 分析最適支付契約的比較靜態結果。在其他條件不變之下，(1) 若買方公司風險趨避態度增加時，買方公司將提高目標公司持股比例的契約設計，增加契約誘因強度，以避免承擔過多企業併購的不確定風險；(2) 當公司價值估計變異風險增加（外在不確定風險增加），若買方公司的風險趨避係數大於目標公司的風險趨避係數時，買方公司將增加目標公司持股比例作為要約；(3) 若買方公司的努力成本增加時，買方公司愈不願意付出努力水準，傾向於提高誘因機制給目標公司增加目標公司的持股比例作要約。 修正訊息結構的假設，引入契約中加入「承諾付出一定努力」的條款，加入「買方承諾」條款時，雙方道德風險的最適契約設計可以簡化為單方道德風險模型。加入「雙方承諾」的條款時，模型則可簡化成以「完全訊息」沒有道德風險問題的方式來分析。比較三個方面的差異：(1) 誘因強度大小的比較：在單方道德風險下，最適目標公司持股比例契約，將大於雙方道德風險模型下設計的最適契約；雙方道德模型則需視彼此道德風險問題的抵換，誘因強度不一定大於完全訊息模型。(2) 比較靜態結果比較：就影響方向而言，風險趨避係數變動，對不同訊息設計影響方向皆相同；外生誤差風險變動時，單方道德風險的影響則確定為負；至於努力成本的影響方向則不變。就影響大小而言，雙方道德風險模型誘因強度敏感性則恆小於單方道德風險模型的影響；與完全訊息的敏感程度大小則不一定。(3) 雙方期望效用總和比較：在雙方道德風險模型下，最適契約符合契約雙方期望效用確定等值極大的條件。 修正風險趨避特性的假設，探討風險中立假設下，最適的簡單線性支付契約適用性的問題。可得在風險中立情況下，只有雙方道德風險模型，混合性支付方式線性契約的誘因機制仍存在。最後，利用「制度性的比較靜態分析」，歸納出企業併購雙方道德風險問題下，當外生變數變動時，「完全現金支付」與「混合性支付方式」的選擇取捨。

本研究之目的在於瞭解臺灣地區有關醫療需求與利用之行為，並進而藉其 研究結果來推估部分負擔之實施成效。針對「八十年家庭收支記帳調查」 之 1,327戶家庭之資料，本研究分別以多元迴歸之線性模型與指數模型來 從事分析，並獲致下列之重要結果及發現： 1.門診價格偏彈性為 -0.27 至 -0.28 之間；住院價格偏彈性為 -0.06之間。可見兩者均欠缺彈性， 且住院較門診的彈性值更小。 2.門診之住院交叉彈性為 0.0015 至 0.0016 之間，顯示門診與住院之間有些替代效果存在。 3.門診之所得偏 彈性係數為 0.19至 0.22之間，表示門診是種正常品，且其彈性值並不大 。 4.部分負擔在門診上所節省之保險給付，若以負擔率為 10%來看，約 佔保費收入之 6.6%至 10.2%；醫療給付之 8.2%至 24.9%。但若提高部分 負擔至 25%時，則上述各數值約增加為兩倍。可見部分負擔對於保險財務 之補充，實具有相當功效。 5.以 10% 至 25% 的門診部分負擔率來估算 ，一般家庭於一年內須自付之門診費用，約佔家庭消費支出之 0.3%至 1.3%，佔儲蓄金額之0.7%至 3.0%，佔可支配所得之 0.2% 至 0.9%。其比 率並不算高，應不至於對一般家庭形成過重之經濟壓力。但若常使用醫療 資源的話，負擔將會更加提高且不容忽視。 / This research attempts to estimate the financial effects of cost-sharing system in Taiwan's health insurance. According to book-keeping data of 1,327 families, the study uses the linear & exponential model of the multiple regression to analyze the demand of the medical resources in Taiwan. The major results are as following: 1. The partial price elasticity of the outpatient care is esti- mated between -0.27 and -0.28, while the partial price elasti- city of the inpatient care is -0.06. Both are inelastic, but the inpatient care is ever more inelastic than the outpatient care. 2. The cross elasticity of the outpatient visits demanded with respect to inpatient price is between 0.0015 and 0.0016. It shows that there are some substitutions between two kinds of medical care. 3. The partial income elasticity of the outpatient care is esti- mated between 0.19 and 0.22, which reveals that the outpatient care is a normal good though the elasticity is small. 4. As to the potential effect of cost-sharing system on saving outpatient benefit, if the cost-sharing ratio were 10%, the reduced payment as the share of the premium is expected from 6.6% to 10.2% and as the share of the medical benefit from 8.2% to 24.9% depending on varying assumptions. If the ratio were raised to 25% , the reduced payment is projected to be twice as above. It implies that the cost-sharing system could be effective to improve the insurance finance. 5. It is further estimated that, when the cost-sharing ratio of the outpatient care were 25%, the cost-sharing burden for an average family is 1.3% with respect to the consumption expend- iture, 3.0% with respect to the savings and 0.9% with respect to disposable income. These ratios are not too high and an av- erage family can afford it. However, for those using medical services more heavily, their burden could be much higher and should be seriously considered.

全民健保自1995年施行以來，已成為照顧國人健康最重要的社會安全措施之一，更創造世界各國稱羨的社會健康保險奇蹟。然由於全民健保的保障，使國人忽略平時對個人健康管理之風險控制，因被保險人心理危險所導致之醫療浪費極為嚴重，醫療費用不斷增加，造成健保財務負擔與效率低落，若不進行調整，將危及健保的永續經營。 從社會福利國演進歷史觀之，社會連帶思想與分配正義原則，雖強調人民具人性尊嚴生存之權利及國家之保護義務，但並非單純將個人風險轉由社會共同承擔，而是以國民對於自我社會責任的履行為前提，因天賦或環境等因素，對於無法以自身能力來克服及排除社會風險所帶來的負面影響，使其無法維持「具人性尊嚴之生存」時，始將該風險轉由社會共同承擔，且以保障其基本生活為原則，以求「禁止過度侵害」與「禁止保護不足」原則間之平衡。因此全民健保雖為社會連帶原則之體現，但仍應以個人責任為基礎。 國內外研究皆指出，與個人直接相關之生活型態及遺傳等因素，為影響健康的主要風險來源，醫療服務的影響力約僅佔一成，而加重被保險人責任可有效抑制心理危險因素，透過部分負擔，誘導被保險人重視個人健康責任，以健康之生活型態配合政府之健康檢查與各種篩檢措施，降低罹病率或及早治療，即使不幸罹患重病亦應遵從醫囑，以最經濟的手段達到必要之治療成效。因此，全民健保為達其增進全體國民健康之目的，應以國人之健康風險控制為主，而非將資源過度投注於醫療費用補助，始為根本之道。 反觀我國全民健保，將絕大多數資源用於治療疾病，卻忽略了預防保健的重要性，亦未強調被保險人對自身健康風險之控制責任，近來健保改革聲浪亦多集中於保費收取、藥價、支付制度等議題，忽略個人健康風險控制與心理危險防範之重要性，造成被保險人對個人健康風險控制的不重視，以及預防保健篩檢率偏低、醫療成本負擔逐漸龐大等種種效應。 本文建議，應強化全民健保健康促進功能，免費提供經濟效益高而侵犯性低之預防保健項目，此外，政府應建立重大遺傳疾病通報制度，提供高風險民眾諮詢與檢測等相關服務。再者，健保給付應以基本醫療需求為限，並兼採自負額與共保制，加重被保險人承擔個人健康風險控制責任，且在制度上與社會救助明確區隔，廢除免部分負擔制度，對無力支付部分負擔者改由社會救助支付，以降低被保險人心理危險因素，藉由健康促進之生活方式與配合政府推行保健措施等健康風險控制手段，降低疾病發生率及健康風險損失幅度，始能達成全民健保增進國人健康之目的，並大幅降低健保醫療支出。

Which factors best explain the regional variation in sick-listing and early retirement? Data from the Swedish Social Insurance Agency is fitted against variables describing different regional characteristics that have been linked to sickness insurance consumption in the literature. Results, in line with earlier empirical investigation, suggest that particularly the employment rate, the populations‟ age, and its wealth are strong determinants of regional insurance usage. Two further factors, though less discussed in the literature, appear to have some relevance as well: A high share of large workplaces is found to predict higher rates of early retirement, while a large share of foreign-born predict lower sick-listing rates. Both effects have been found before, though the first one perhaps not in Swedish cross section analysis and the latter does not appear to be well understood in the literature. A tentative explanation for it is given here.

<p>Which factors best explain the regional variation in sick-listing and early retirement? Data from the Swedish Social Insurance Agency is fitted against variables describing different regional characteristics that have been linked to sickness insurance consumption in the literature. Results, in line with earlier empirical investigation, suggest that particularly the employment rate, the populations‟ age, and its wealth are strong determinants of regional insurance usage. Two further factors, though less discussed in the literature, appear to have some relevance as well: A high share of large workplaces is found to predict higher rates of early retirement, while a large share of foreign-born predict lower sick-listing rates. Both effects have been found before, though the first one perhaps not in Swedish cross section analysis and the latter does not appear to be well understood in the literature. A tentative explanation for it is given here.</p>

This thesis is concerned with recursive partitioning of models of a generalized linear model type (GLM-type), i.e., maximum likelihood models with a linear predictor for the linked mean, a topic that has received constant interest over the last twenty years. The resulting tree (a ''model tree'') can be seen as an extension of classic trees, to allow for a GLM-type model in the partitions. In this work, the focus lies on applied and computational aspects of model trees with GLM-type node models to work out different areas where application of the combination of parametric models and trees will be beneficial and to build a computational scaffold for future application of model trees. In the first part, model trees are defined and some algorithms for fitting model trees with GLM-type node model are reviewed and compared in terms of their properties of tree induction and node model fitting. Additionally, the design of a particularly versatile algorithm, the MOB algorithm (Zeileis et al. 2008) in R is described and an in-depth discussion of how the functionality offered can be extended to various GLM-type models is provided. This is highlighted by an example of using partitioned negative binomial models for investigating the effect of health care incentives. Part 2 consists of three research articles where model trees are applied to different problems that frequently occur in the social sciences. The first uses trees with GLM-type node models and applies it to a data set of voters, who show a non-monotone relationship between the frequency of attending past elections and the turnout in 2004. Three different type of model tree algorithms are used to investigate this phenomenon and for two the resulting trees can explain the counter-intuitive finding. Here model tress are used to learn a nonlinear relationship between a target model and a big number of candidate variables to provide more insight into a data set. A second application area is also discussed, namely using model trees to detect ill-fitting subsets in the data. The second article uses model trees to model the number of fatalities in Afghanistan war, based on the WikiLeaks Afghanistan war diary. Data pre-processing with a topic model generates predictors that are used as explanatory variables in a model tree for overdispersed count data. Here the combination of model trees and topic models allows to flexibly analyse database data, frequently encountered in data journalism, and provides a coherent description of fatalities in the Afghanistan war. The third paper uses a new framework built around model trees to approach the classic problem of segmentation, frequently encountered in marketing and management science. Here, the framework is used for segmentation of a sample of the US electorate for identifying likely and unlikely voters. It is shown that the framework's model trees enable accurate identification which in turn allows efficient targeted mobilisation of eligible voters. (author's abstract)