Human decision making is closely related to reward processing because many decisions rely to a certain degree on the evaluation of different outcome values. Reward-based decisions can be health-related, for example if someone has to compare the outcome value of the instant reward of smoking a cigarette to that of the long term goal of keeping well and fit. Such comparisons do not only rely on the nominal value of the alternatives but also on devaluation of rewards over time. The value of being healthy at older age might outweigh the value of smoking a cigarette but since the payoff of the health-outcome will be delayed, humans tend to decrease the value of this option. Therefore in this example one might choose the immediate reward of smoking a cigarette. The proclivity to devaluate the value of rewards over time has been widely investigated with experimental intertemporal choice tasks, in which subjects have to choose between smaller sooner rewards and larger later rewards. A stronger individual devaluation proclivity (i.e. discounting rate) has been reported to be related to addiction. Research in neuroeconomics has suggested the competing neurobehavioural decision systems (CNDS) theory, proposing that an imbalance between an executive (cortical prefrontal brain areas) and an impulsive (i.e. subcortical areas, such as ventral striatum (VS), amygdala) system in the brain leads to steeper discounting and a higher risk for addiction. Additionally, temporal discounting has been proposed as a transdisease process, i.e., “a process that occurs across a range of disorders, making findings from one disorder relevant to other disorders” (Bickel, Jarmolowicz, Mueller, Koffarnus, & Gatchalian, 2012, Abstract). Thus, the CNDS theory and temporal discounting might also have implications for other health-related behaviour than substance use. So far many factors have been shown to be associated with higher discount rates: for instance, adolescent age, lower intelligence and nicotine dependence. Further, it has been shown that adolescents are at highest risk to start smoking. On the other hand a higher education level has been shown to be associated to lower rates of smoking. Thus, it seems likely that a higher discount rate might be one reason why adolescents experiment with smoking, why lower education is associated to nicotine addiction and why dependent smokers are not successful in smoking cessation. But relatively little is known about the neural processes behind these variables, which could be also seen as exemplary risk- and protective factors regarding addiction. The 3 studies of the thesis at hand were conducted to extend the knowledge about neural processes associated to age, intelligence and smoking in their relation to intertemporal choice. The task was chosen because of its relevance for addiction and a variety of health-related behaviour. The first study was conducted to explore the neural correlates of age related differences between adolescents at age 14 and young adults during intertemporal choices. Additionally, the roles of discounting and choice consistency were investigated. Although adoles-cents discounted delayed rewards more steeply than adults, neural processing of reward value did not differ between groups, when controlling reward values for the individual discount rates. However, a higher discount rate was related to a lower responsivity in the ventral striatum to delayed rewards, independent of age. Concerning decision making, adolescents exhib-ited a lower consistency of choices and less brain activity in a parietal network than adults (i.e. posterior and inferior parietal regions). Thus, reward value processing might be more sensitive to the discount rate than to chronological age. Lower consistency of intertemporal choices might indicate ongoing maturation of parietal brain areas from adolescence to young adulthood. The second study was conducted to reveal the associations between neural processes of decision making and intelligence in adolescents. The results of study 2 revealed networks in the adolescent brain where brain activity was related to crystallised intelligence as well as to intertemporal choice behaviour. Specifically, during decision processing higher crystallised intelligence as well as more consistent decisions were associated with higher brain activity in the posterior parietal cortex. Processing of delayed rewards was also related to crystallised intelligence, i.e. more intelligent adolescents showed higher brain activation in the anterior cingulate cortex (ACC) and the inferior frontal gyrus (IFG), which was in turn related to a lower discount rate. Additionally, associations between the parental education level and crys-tallised intelligence of the adolescent participants of the study and their discount rate were found, indicating that parental education as an environmental factor could be related to a low-er risk for addiction. This protective effect might be mediated by the offspring’s crystallised intelligence and discount rate which are both related to brain activity in parts of the same brain networks (i.e. the IFG). The third study was done to investigate neural processes of intertemporal decisions in smokers and non-smokers. To test whether the effects of smoking on the discount rate are due to chronic or acute nicotine intake, non-smokers were additionally assessed under acute nico-tine administration. Study 3 revealed that the effects of nicotine on intertemporal choice behaviour were related to chronic intake of nicotine in smokers rather than to acute nicotine ad-ministration in non-smokers. Regarding the neural processes, smokers compared to non-smokers showed lower brain activity in the posterior parietal cortex. Comparable but weaker effects were found under acute nicotine in non-smokers. Although acute nicotine administra-tion altered neural processes, behavioural changes might only occur after repeated nicotine intake. However, the study did not preclude that the differences are predrug characteristics. Altogether the studies revealed overlapping neural correlates of intertemporal choices which are related to the individual age, the discount rate, the choice consistency, the individual intelligence as well as acute and chronic nicotine intake. This might provide an integrative view on how inter-individual differences and behaviour during intertemporal choices are based on common neural correlates which in turn might have implications for the development and the maintenance of addiction. Specifically, hyposensitivity towards delayed rewards in the adolescent ventral striatum, which has also been found in smokers compared to non-smokers, is associated with higher discount rates and higher risk for smoking initiation. In contrast, higher activation in the IFG and the ACC in more intelligent individuals during reward value processing might enhance behavioural inhibition and control and, hence, might prevent nicotine addiction. In line with the CNDS theory responsivity in subcortical brain areas (i.e. impulsive system), such as the VS was related to the risk factor of adolescent age, whereas activity in cortical areas (IFG and ACC) was related to the protective factors of high-er crystallised intelligence. Since there was only one study beside the studies of the current thesis reporting results regarding consistency, one can only speculate about implications for health-related behaviour, such as addiction. Consistency might play a role, especially for cessation success. Thus, the findings that adolescents as well as less intelligent individuals were less consistent might point to a higher risk for maintenance of nicotine addiction. The higher brain activity in a fronto-parietal network, which has been shown in studies 1 and 2 in adults as well as in more intelligent adolescents, was related to higher consistency of choices in both studies. Thus, the finding might be a possible neural correlate for the association between the risk factor of ado-lescent age, the protective factor of higher crystallised intelligence, and more consistent deci-sion making. In conclusion the findings of the current thesis contribute to a better understanding of how inter-individual differences and environmental factors might be accompanied by neural processes which in turn might be related to individual development of addiction. Further the results might extend the CNDS theory regarding neural correlates of exemplary risk and pro-tective factors regarding adolescents’ health behaviour and smoking in adults.

Background: Serotonin has been implicated in impulsive behaviours such as temporal discounting. While animal studies and theoretical approaches suggest that reduced tonic serotonin levels increase temporal discounting rates and vice versa, evidence from human studies is scarce and inconclusive. Furthermore, an important modulator of serotonin signalling, a genetic variation in the promoter region of the serotonin transporter gene (5-HTTLPR), has not been investigated for temporal discounting so far. Objective: First, the purpose of this study was to test for a significant association between 5-HTTLPR and temporal discounting. Second, we wished to investigate the effect of high/low tonic serotonin levels on intertemporal choice and blood oxygen-level-dependent response, controlling for 5-HTTLPR. Methods: We tested the association of 5-HTTLPR with temporal discounting rates using an intertemporal choice task in 611 individuals. We then manipulated tonic serotonin levels with acute tryptophan interventions (depletion, loading, balanced) in a subsample of 45 short (S)-allele and 45 long (L)/L-allele carriers in a randomised double-blind crossover design using functional magnetic resonance imaging and an intertemporal choice task. Results: Overall, we did not find any effect of serotonin and 5-HTTLPR on temporal discounting rates or the brain networks associated with valuation and cognitive control. Conclusion: Our findings indicate that serotonin may not be directly involved in choices including delays on longer timescales such as days, weeks or months. We speculate that serotonin plays a stronger role in dynamic intertemporal choice tasks where the delays are on a timescale of seconds and hence are therefore directly experienced during the experiment.

The purpose of this thesis is to examine the monetary policy of the Swedish central bank, Riksbanken, from the perspective of the Austrian School of Economics. The thesis starts with a description of the actions of Riksbanken, its objectives of the monetary policy and what tools are used to achieve those objectives. The thesis continues with an analysis of possible consequences for the Swedish business cycles that the monetary policy of Riksbanken may have caused. The theory that is used to answer the research question is Austrian economic theory and primarily Austrian Business Cycle Theory. A review of relevant theory is made, and an examination of relevant macroeconomic factors is produced. The examination shows that the factors have changed over time according to the prediction of the Austrian School of Economics. The Riksbank's monetary policy decisions have been affected by concerns about the household indebtedness. This concern is in line with the warnings of the Austrian school. The Riksbank has, on the other hand, not considered the Austrian schools' fears of malinvestment and artificial boom in its monetary policy decisions. The conclusion of the essay is that the monetary policy of Riksbanken may contribute to strengthening business cycles, according with the perspective of the Austrian School of Economics. If the inflation prognosis’s from Riksbanken would have been correct, they probably had exercised a more aggressive monetary policy, primary by lowering the interest rate. It would have increased the variations of the business cycles trough increasing the gap between the natural interest rate and the market rate. / Syftet med uppsatsen är att granska Riksbankens penningpolitik utifrån den österrikiska skolans synsätt. Uppsatsen redogör för Riksbankens mål för penningpolitiken och vilka verktyg de använder för att uppnå dessa. Granskningen av den förda penningpolitiken genomförs utifrån den österrikiska ekonomiska teorin, främst dess konjunkturcykelteori. En genomgång av denna teori genomförs, och en analys av bakomliggande faktorer utförs. Analysen slår fast att de flesta av de undersökta variablerna har förändrat i linje med vad som kan förväntas enligt den österrikiska teorin. Riksbankens penningpolitiska beslut har påverkats av oron för hushållen skuldsättning. Denna oro ligger i linje med vad österrikiska skolan varnar för. Den österrikiska skolans farhågor för felinvesteringar och konstlad högkonjunktur har Riksbanken däremot inte tagit hänsyn till i sina penningpolitiska beslut. Slutsatsen för uppsatsen blir att Riksbankens penningpolitik kan ha bidragit till att förstärka konjunktursvängningarna. I det fall att Riksbankens inflationsprognoser varit mer träffsäkra, skulle de under större delen av perioden enligt sina egna handlingsregler ha fört en mer aggressiv penningpolitik, främst genom lägre styrränta. Det skulle i så fall stärkt konjunktursvängningarna än mer enligt den österrikiska konjukturcykelteorin.

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本論文目的在於探討「異質期望」(heterogeneous expectations)、「資訊密度」(information arrival intensity)、以及「跳躍風險」(jump risk) 這些因素對於期貨價格的影響，並且透由「跨期模型」(intertemporal models) 的建立，推導出具有封閉解形式的期貨價格理論公式。 誠如 Harrison and Kreps (1978) 所言：除非所有市場參與者的行為方式完全相同、而且他們都打算抱著股票直到永遠，否則「投機交易」(speculation transactions) 與「異質期望」就不可能自市場當中滅絕。有鑑於此，本論文在第二章中討論「異質期望」對於期貨價格的影響；同時為了反映交易者看法可能會隨時間演進而發生改變的可能性，「調整效果」(adjustment effects) 是本章另一個討論重點；第三、為了區別期貨契約與遠期契約的基本差異，「利率」這個隨機因子也被納入模型當中。由「部分均衡」(partial equilibrium) 觀點下具有封閉解形式的期貨價格公式來觀察，這三個重要因素以及彼此間存在著的複雜交互作用，可以協助解釋一些實證現象與重要變數之間的關係。 第三章主要是借用Clark (1973) 與Chang et al. (1988) 「資訊時間」(information time) 的概念，取代一般模型所使用的「日曆時間」(calendar time) 設定方法，並且額外納入「利率」與「便利所得」(convenience yield) 這兩個廣為一般期貨定價文獻所認定的重要隨機因素，推導出「部分均衡」觀點下的期貨價格封閉解。根據1998/7/21 至 2003/12/31 台灣期交所「台灣證券交易所總加權股價指數期貨」的實證結果來看，本章模型的定價績效不僅勝過「持有成本模型」(the cost of carry model)，也比同時考慮「利率」與「便利所得」兩個隨機因子的「日曆時間」模型要來的好。 第四章則是嘗試結合Hemler and Longstaff (1991) 的「無偏好模型」(preference-free model) 以及Merton (1976) 的「跳躍」(jumps) 設定，重新推導「一般均衡」(general equilibrium) 模型下、考慮「跳躍風險」(jump risk) 後的期貨價格封閉解。根據本章各種比較靜態與模擬分析的結果顯示，整個經濟體系或是「狀態變數」(state variables) 的安定程度，決定了市場變數間的關係；另一方面，這些關聯會因為「跳躍風險」規模的遞增 — 不管是肇因於「發生機率」(occurring probability) 或是「衝擊效果」(impulse effect) — 而變的更加不可預測。 / The dissertation contains three essays on intertemporal futures pricing models allowing for heterogeneous expectations, information-time based setting, and jump risk. As Harrison and Kreps (1978) have noted, unless traders are all identical and obliged to hold a stock forever, speculation would not extinguish in market, and heterogeneity in expectations yields whereby. The first essay develops intertemporal futures pricing formulas accounting for such reality, adjustment effect, and stochastic interest rate in a partial-equilibrium sense. The closed-form solutions show that the three factors complicated with each others can help to explain some existing empirics on relationships between futures prices and other important market variables such as indeterminate converging pattern. The second essay extends Chang et al. (1988) option pricing model to derive futures prices with information-time based processes. Stochastic interest rate and convenience yield are also taken into account to derive closed-form formulas. According to empirical results of transaction data of TAIEX index and its corresponding TFETX futures contract through 1998/7/21 to 2003/12/31, the analytic solution performs better than the cost of carry model and its calendar-time based counterpart, especially when information arrival intensity estimates become larger. The last essay combines Hemler and Longstaff’s (1991) preference-free model and Merton’s (1976) jump setting to measure effects from jump risk and a futures pricing formula is derived in its closed-form as well. According to miscellaneous comparative static and simulation results, the bounded degrees of state variables, or economy, affect co-varying extents among variables, while the increasing jump risk, including the size of occurring probability and its corresponding impulse effect, makes them un-tractable.

近年來，信用衍生性金融商品蓬勃發展，市場上陸續出現不同特色的信用擔保憑證。過去評價信用衍生性金融商品多採用Hull & White (2004)年所發表的因子相關結構型模型(factor copula approach)。由於因子相關模型在描述違約事件，可降低處理維度，使得計算更容易處理，更方便建立出損失分配，讓評價工作更順利進行。但是，降低維度的便利，卻犧牲了違約時點的動態描述，在因子模型中，我們無法掌握損失分配的期間結構，所以只能處理單一到期日的信用衍生性金融商品。 但市場上逐漸出現具有時間相關性的信用金融商品，例如：遠期生效型信用擔保憑證(Forward-starting CDO)、信用擔保憑證分券選擇權(Option on CDO tranches)、重設型信用擔保憑證等。其中遠期生效契約的特色在於，在生效日之前，標的資產若違約，並不構成損失的發生，只會將此商品從投資標的中剔除。故投資人在生效日之前，受到一層信用保護，所以相較於同天到期的信用擔保憑證，會使遠期契約的信用價差會比較低，可降低發行商的成本。在加上近年來，信用曲線出現越來越陡峭的情形，代表到期日相差越長，報酬差異越大，所以投資較長天期的商品，相對報酬提高較多。而次順位分券信用價差近年來下降許多，不少投資人為了達到報酬目標，轉而投資較長天期的信用投資產品。而且信用曲線過於陡峭，投資人預期未來違約環境會呈現平緩或變佳的趨勢，可以透過購買遠期契約，來獲得投資利潤。 由於我們不想放棄因子相關性結構模型在使用上簡便的優勢，所以試圖將跨期相關因子引入因子模型，將期間之間的相關性考慮進去，讓遠期生效信用擔保憑證的評價工作得以運行。除此之外，我們分析各分券對參數的敏感性，並加以探討其中的經濟意涵，最後以討論遠期信用擔保憑證避險的策略作結。

本研究共包含三篇論文，首先修正von Hagen and Hepp(2000)所建立模型分析政府的財源轉移之風險分散與重分配動態效果。整體而言，補助與協助收入或統籌分配款所產生的所得與稅收風險分散或重分配效果相當有限，且各分區(北、中、南與全區)的結論差異甚大，顯示財源轉移發揮的效率不足。統籌分配款對於改善稅收的風險分散與重分配上，效果優於補助與協助收入。各縣市取得的補助與協助收入或統籌分配款高於長期所得與稅收風險分散與重分配所應對應的額度，造成資源浪費。就全區而言，前幾期稅收(所得)風險分散變化，可作為短期調整補助與協助收入(統籌分配款)的依據；統籌分配款與稅收的風險分散、補助與協助收入或統籌分配款與稅收重分配均存在雙向因果關係。 其次，在分析勞動者的休閒時間選擇時，本文修正跨期選擇模型，考慮勞動者持有投資組合與採取避險措施，並面對租稅問題下，以導出休閒時間方程式。實證上採用混合估計法針對12種樣本產業及兩種不同休閒時間衡量方式進行估計，結果顯示不同休閒時間衡量方式，影響估計結果甚鉅；金融市場的變化與波動攸關休閒時間變動：國內外利率、匯率與遠期匯率等與投資組合報酬相關的變數，在多數情況下顯著地影響休閒時間變動，且各變數對於休閒時間的影響程度，在工業中的次級產業大於服務業中的次產業。此外，採行周休二日制度確實改變制度採行前後的休閒時間，惟在三個工業次產業上則不明顯。 最後，修正Bo and Sterken (2002) 所建立的最適動態模型，分析公司價值不確定與租稅措施對海運廠商投資的影響，經由最大化公司價值導出影響台灣海運公司投資的三種不確定來源與避險措施，並進行實證估計。實證結果顯示，不確定的衡量方式攸關投資函數的估計結果，以指數加權移動平均標準差衡量不確定時，其估計結果優於以GARCH(1,1)衡量不確定，隱含廠商較在乎可預期波動對投資的影響。一般而言，廠商利率與原油價格的波動增加，均不利於公司投資，其中以原油價格不確定對於投資的影響最大，其效果約略與廠商利率相當。其次，影響海運公司投資最重要的三項因素均分別為BDI、負債與廠商利率，顯示價格與債務規模的重要性更甚於利率。此外，三種公司價值不確定來源對投資的影響，在多數個別公司之間並無顯著的差異，有助於採行總體財金政策以刺激投資。 / This dissertation contains three articles. First I revise the models set up by von Hagen and Hepp (2000) to analyze the dynamic effects of the Aid and Assistance and central government’s Tax Redistribution Fund on income (or tax) risk sharing and redistribution. For all the counties in Taiwan area the effects are tiny, but those are diverse among the counties in each Taiwan sub-area. The Aid and Assistance and central government’s Tax Redistribution Fund actually obtained by each county are larger than the amounts required to maintain long-term risk sharing and redistribution effects. These all imply that fiscal transfer is inefficiency. The effects of the central government’s Tax Redistribution Fund on risk sharing and redistribution are larger than those of Aid and Assistance. The central government can adjust the Aid and Assistance based on the change of earlier-period ax (income) risk sharing effect. Moreover, the existence of significant short-run interaction between the central government’s Tax Redistribution Fund and tax risk sharing, the Aid and Assistance and tax redistribution. Secondly, I revise intertemporal choice model by considering portfolio selection, hedging and taxation problems to derive economic agent’s leisure time equation. In empirical study, we focus on twelve sample industries and two different leisure time measurements, then adopt pooled estimation to estimate leisure time equation. Empirical results show that different measurement of leisure time influences estimation outcomes tremendously. Furthermore, the financial variables affecting portfolio return, including domestic and foreign interest rates, exchange rate and forward rate almost have remarkable effect on leisure time. Finally, the effect of each explanatory variable on leisure time is larger in industry than in service industry. Finally, I revise the optimal intertemporal model, constructed by Bo and Sterken (2002), by maximizing corporate value to derive three uncertainty sources and hedging influencing shipping-firm investment. Empirical evidences show that it is relevant for the estimation results to adopt which methods to measure the uncertainty. The outcomes derived from taking the Exponential Weighted Moving Average model to measure uncertainty are better than those from adopting the GARCH(1,1) model. Generally, as the volatilities in firm’s interest rate and crude oil price increase, firm investment decreases and the effect of crude oil price uncertainty on investment, the largest among the four effects, is nearly equal to that of firm interest rate on investment. Furthermore, BDI, debt and firm interest rate are the most important variables influencing firm investment. Finally, the effects of three uncertainty sources on investment are almost indifferent among the ten shipping-firms.

本文研究保險人於匯率風險下之最適跨期投資組合。隨著資本市場全球化發展，從事國外投資受到匯率風險之影響加劇。本研究提出動態投資組合模型，針對壽險業之利變型商品，分析保險人於匯率風險之下之最適跨期投資組合。考慮資產集合包含本國現金、本國指數型股票基金、外國現金和外國指數型股票基金四項標的。本文研究方法主要以Cox & Huang(1989, 1991)平賭理論處理最適投資議題，將多期問題變為單期，求得保險人之最適投資組合。最後本文針對不同的匯率走勢與匯率風險波動度，利用電腦模擬，觀察不同風險趨避程度保險人之投資組合變化。 本文結果歸納如下： 1. 於風險市場價值、波動度和國內外無風險短期利率為定值下，保險人最適組合分別是擁有固定比例本國股票部位，外國股票部位則與匯率走勢呈負相關，而本國現金部位與外國現金部位呈現相反趨勢。發現匯率增量趨勢與外國現金帳戶、外國指數型股票基金和本國現金部位趨勢相同。 2. 匯率風險將影響保險人持有外國資產意願。若匯率風險波動度由0.1提高至0.3，則外國現金部位之最大值會從6.23下降到0.66。而外國股票持有部位於短期會增加，但隨著投資期限增加而逐漸遞減。同時短期增加之幅度小於外國現金減少之部分。整體而言，持有外國資產比例隨匯率風險波動度變大而遞減。 關鍵字：匯率風險、跨期投資組合、平賭理論、風險波動度、電腦模擬

The study of economic crises has been a major topic of interest in economics since at least the Great Depression and it has come to the fore once again after the latest crisis of late 2000s. It has also been one of the key themes for the Austrian school of economics in the form of the Austrian Business Cycle Theory (ABCT), which puts emphasis on monetary factors influencing capital structure of the economy. In this thesis we provide a comprehensive exposition of the distinctive points of Austrian approach to the study of markets, the ABCT's propositions and conclusions and also the most important criticism of the theory and replies to it. The theoretical part is accompanied by an empirical illustration on the economy of the United States of America in the period starting at the end of the latest crisis. Powered by TCPDF (www.tcpdf.org)

L’objectif de la thèse est d’identifier la pertinence des modèles en équilibre général calculable (MEGC) pour analyser la problématique posée par les Accords de Partenariat Économique (APE) entre l’Union européenne et les pays ACP. Une revue de la littérature est d’abord réalisée, puis un modèle en équilibre général calculable (MEGC) à dynamique intertemporelle est construit pour analyser l’impact de l’APE sur un pays spécifique : le Ghana. À partir du constat portant sur la diversité des résultats de simulations, qui dépendent essentiellement de la structure du modèle et des modes de fermeture choisis par le modélisateur, ce travail cherche à mettre en évidence la largeur du faisceau de résultats possibles et l’impossibilité de mettre en avant les bénéfices potentiels qui peuvent être attendus d’un tel accord en s’appuyant simplement sur des MEGC néoclassiques standards. / This work aims to analyze to what extent the use of an applied general equilibrium model (AGE) allows to correctly assess the potential economic impact of EPAs between ACP countries and the European Union. First, a review of the literature is conducted and then an intertemporal dynamic AGE model is built in order to assess the potential impact of EPA on a specific country: Ghana. From the variety of results resulting from the models simulations and depending on hypothesis made on the model structure and the type of closure chosen by the modeler, our work aims to stress the risk of using standard neoclassical Walrasian models to assess the potential benefits of an EPA on ACP countries economy.