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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

巨量資料與隱私權─個人資料保護機制的再思考 / Big data and privacy: Rethinking personal data protection mechanisms

鍾孝宇, Chung, Hsiao Yu Unknown Date (has links)
本文主張,隱私是公民社會的構成元素,它保障個人在社會建構的形塑之下,保有日常行為實踐的能動性,得在自我自主經驗與社會建構的來回探索之間,生成個人的主體性。這個動態的主體性發展空間,使我們得以開拓環境中的意外發現並建立心智的批判獨立性,具備如此公民特質的社會,才有能力促進自我決定、創新、人際交往互動等實踐可能性,形塑健全的公民社會。 然而,巨量資料在數位環境中,正全面影響我們日常行為實踐的模式。巨量資料以統計相關性的知識論與方法論,形成不同的洞察與價值,其以資料驅動技術所辨識出的現象模式,建立其宣稱的客觀性優勢。巨量資料脈絡下的數位技術物,不僅是日常生活的輔助工具,而毋寧是我們個人感官的延伸,其精巧的影響我們與周遭世界的關係,積極介入、給予指示、引導行為,甚至定義我們的身分,調整、調控我們的行為。作為一種知識生產與治理模式,巨量資料的監控本質對於個人或群體所加諸的權力作用,將削弱個人主體性的發展空間,進而影響健全的公民社會發展,形成新型態的、難以察覺的隱私權侵害風險。並且,本文認為,商業監控結合監控資本主義邏輯的調控治理,對於公民社會的傷害更鉅。 面臨如此的風險,本文指出作為資訊社會產物的現行個人資料保護機制,無法回應數位環境中巨量資料隱私威脅的三個因素:個人資料性質的改變、告知與同意機制的失敗、資料汙染。並在奠基於隱私權的社會價值理論之上,提出三種原則性建議:巨量資料的應用倫理、巨量資料利用的正當程序原則、社會責任與自律規範。在原則性建議以外,亦將視角拉回我國的個人資料保護機制,參考歐盟一般資料保護規則的相關立法,建議我國應盡速設置專責之資料保護監管機構,並提供具體的個人資料保護規範修法方向:創設涵蓋資料保護影響評估的資料管理機制、建置組織內部資料利用監督機制、以及創設使用者的資料可攜權。
92

金融科技與投資產業 : 新商業模式 / Fintech and Investment : New Business Models

李齊良, Lee, Chi Liang Unknown Date (has links)
摘要 自2008年金融風暴後,長期的經濟動盪造成顧客喪失對於傳統投資產業之信心。在這樣的環境下,從自動化投資管理、社群交易平台到零售演算法交易的興起,提供低成本與先進的替代方案取代傳統的投資管理產業。這種方式獲得廣大消費者的信賴,並使得顧客擁有更多投資管理之控制權。 本研究欲探討賦權投資者於金融科技的浪潮下,競爭者加入後所面臨之挑戰進行情境分析,了解投資者如何以自動化管理及報告、社群交易平台和零售演算法交易改變投資管理業之發展,並使得傳統以顧問諮詢為主的投資管理興起全自動化或財務顧問協助之新商業模式;再者,透過個案分析,分別探討自動化管理及報告為代表之機器人理財公司以及零售演算法交易平台Quantopian,並建議投資產業應善用金融科技結合兩者,因此,未來顧問所扮演的角色將轉型為從旁協助財務規劃之服務,不僅能夠降低成本,亦可大幅提升理專的效率,為更廣大的客群提供高價值之金融服務。 / Abstract The 2008 financial crisis was the worst economic disaster since it has caused public losing confidence in traditional investement management industry. As a result, the three key innovation clusters are booming─automated management and advice, retail algorithmic trading and social trading platform─that offer lower-cost and advanced alternatives to replace the traditional investement management industry. Additionally, those innovation clusters gain more trust to the masses and allow customers to control in their own investment portfolio. This study analyzes three scenarios how the empowered investors face the challenges under the new waves of Fintech. In particular, we consider the investment management industry transfer the traditional model to the new business models of fully automation or advisor-assistant. In the case studies, we compare six typical robo-advisor firms and retail algorithmic trading platform like Quantopian. Furthermore, we suggest that the investment industry should make good use of Fintech that combines both advantage of automated management and retail algorithmic trading;therefore, it can not only reduce costs but also improve the efficiency of financial services.
93

利用混合模型估計風險值的探討

阮建豐 Unknown Date (has links)
風險值大多是在假設資產報酬為常態分配下計算而得的,但是這個假設與實際的資產報酬分配不一致,因為很多研究者都發現實際的資產報酬分配都有厚尾的現象,也就是極端事件的發生機率遠比常態假設要來的高,因此利用常態假設來計算風險值對於真實損失的衡量不是很恰當。 針對這個問題,本論文以歷史模擬法、變異數-共變異數法、混合常態模型來模擬報酬率的分配,並依給定的信賴水準估算出風險值,其中混合常態模型的參數是利用準貝式最大概似估計法及EM演算法來估計;然後利用三種風險值的評量方法:回溯測試、前向測試與二項檢定,來評判三種估算風險值方法的優劣。 經由實證結果發現: 1.報酬率分配在左尾臨界機率1%有較明顯厚尾的現象。 2.利用混合常態分配來模擬報酬率分配會比另外兩種方法更能準確的捕捉到左尾臨界機率1%的厚尾。 3.混合常態模型的峰態係數值接近於真實報酬率分配的峰態係數值,因此我們可以確認混合常態模型可以捕捉高峰的現象。 關鍵字:風險值、厚尾、歷史模擬法、變異數-共變異教法、混合常態模型、準貝式最大概似估計法、EM演算法、回溯測試、前向測試、高峰 / Initially, Value at Risk (VaR) is calculated by assuming that the underline asset return is normal distribution, but this assumption sometimes does not consist with the actual distribution of asset return. Many researchers have found that the actual distribution of the underline asset return have Fat-Tail, extreme value events, character. So under normal distribution assumption, the VaR value is improper compared with the actual losses. The paper discuss three methods. Historical Simulated method - Variance-Covariance method and Mixture Normal .simulating those asset, return and VaR by given proper confidence level. About the Mixture Normal Distribution, we use both EM algorithm and Quasi-Bayesian MLE calculating its parameters. Finally, we use tree VaR testing methods, Back test、Forward tes and Binomial test -----comparing its VaR loss probability We find the following results: 1.Under 1% left-tail critical probability, asset return distribution has significant Fat-tail character. 2.Using Mixture Normal distribution we can catch more Fat-tail character precisely than the other two methods. 3.The kurtosis of Mixture Normal is close to the actual kurtosis, this means that the Mixture Normal distribution can catch the Leptokurtosis phenomenon. Key words: Value at Risk、VaR、Fat tail、Historical simulation method、 Variance-Covariance method、Mixture Normal distribution、Quasi-Bayesian MLE、EM algorithm、Back test、 Forward test、 Leptokurtosis
94

變數轉換之離群值偵測 / Detection of Outliers with Data Transformation

吳秉勳, David Wu Unknown Date (has links)
在迴歸分析中,當資料中存在很多離群值時,偵測的工作變得非常不容易。 在此狀況下,我們無法使用傳統的殘差分析正確地偵測出其是否存在,此現象稱為遮蔽效應(The Masking Effect)。 而為了避免此效應的發生,我們利用最小中位數穩健迴歸估計值(Least Median Squares Estimator)正確地找出這些群集離群值,此估計值擁有最大即50﹪的容離值 (Breakdown point)。 在這篇論文中,用來求出最小中位數穩健迴歸估計值的演算法稱為步進搜尋演算法 (the Forward Search Algorithm)。 結果顯示,我們可以利用此演算法得到的穩健迴歸估計值,很快並有效率的找出資料中的群集離群值;另外,更進一步的結果顯示,我們只需從資料中隨機選取一百次子集,並進行步進搜尋,即可得到概似的穩健迴歸估計值並正確的找出那些群集離群值。 最後,我們利用鐘乳石圖(Stalactite Plot)列出所有被偵測到的離群值。 在多變量資料中,我們若使用Mahalanobis距離也會遭遇到同樣的屏蔽效應。 而此一問題,隨著另一高度穩健估計值的採用,亦可迎刃而解。 此估計值稱為最小體積橢圓體估計值 (Minimum Volume Ellipsoid),其亦擁有最大即50﹪的容離值。 在此,我們也利用步進搜尋法求出此估計值,並利用鐘乳石圖列出所有被偵測到的離群值。 這篇論文的第二部分則利用變數轉換的技巧將迴歸資料中的殘差項常態化並且加強其等變異的特性以利後續的資料分析。 在步進搜尋進行的過程中,我們觀察分數統計量(Score Statistic)和其他相關診斷統計量的變化。 結果顯示,這些統計量一起提供了有關轉換參數選取豐富的資訊,並且我們亦可從步進搜尋進行的過程中觀察出某些離群值對參數選取的影響。 / Detecting regression outliers is not trivial when there are many of them. The methods of using classical diagnostic plots sometimes fail to detect them. This phenomenon is known as the masking effect. To avoid this, we propose to find out those multiple outliers by using a highly robust regression estimator called the least median squares (LMS) estimator which has maximal breakdown point. The algorithm in search of the LMS estimator is called the forward search algorithm. The estimator found by the forward search is shown to lead to the rapid detection of multiple outliers. Furthermore, the result reveals that 100 repeats of a simple forward search from a random starting subset are shown to provide sufficiently robust parameter estimators to reveal multiple outliers. Finally, those detected outliers are exhibited by the stalactite plot that shows greatly stable pattern of them. Referring to multivariate data, the Mahalanobis distance also suffers from the masking effect that can be remedied by using a highly robust estimator called the minimum volume ellipsoid (MVE) estimator. It can also be found by using the forward search algorithm and it also has maximal breakdown point. The detected outliers are then displayed in the stalactite plot. The second part of this dissertation is the transformation of regression data so that the approximate normality and the homogeneity of the residuals can be achieved. During the process of the forward search, we monitor the quantity of interest called score statistic and some other diagnostic plots. They jointly provide a wealth of information about transformation along with the effect of individual observation on this statistic.
95

狀態轉換下利率與跳躍風險股票報酬之歐式選擇權評價與實證分析 / Option Pricing and Empirical Analysis for Interest Rate and Stock Index Return with Regime-Switching Model and Dependent Jump Risks

巫柏成, Wu, Po Cheng Unknown Date (has links)
Chen, Chang, Wen and Lin (2013)提出馬可夫調控跳躍過程模型(MMJDM)描述股價指數報酬率,布朗運動項、跳躍項之頻率與市場狀態有關。然而,利率並非常數,本論文以狀態轉換模型配適零息債劵之動態過程,提出狀態轉換下的利率與具跳躍風險的股票報酬之二維模型(MMJDMSI),並以1999年至2013年的道瓊工業指數與S&P 500指數和同期間之一年期美國國庫劵價格為實證資料,採用EM演算法取得參數估計值。經由概似比檢定結果顯示無論道瓊工業指數還是S&P 500指數,狀態轉換下利率與跳躍風險之股票報酬二維模型更適合描述報酬率。接著,利用Esscher轉換法推導出各模型下的股價指數之歐式買權定價公式,再對MMJDMSI模型進行敏感度分析以評估模型參數發生變動時對於定價公式的影響。最後,以實證資料對各模型進行模型校準及計算隱含波動度,結果顯示MMJDMSI在價內及價外時定價誤差為最小或次小,且此模型亦能呈現出波動度微笑曲線之現象。 / To model asset return, Chen, Chang, Wen and Lin (2013) proposed Markov-Modulated Jump Diffusion Model (MMJDM) assuming that the Brownian motion term and jump frequency are all related to market states. In fact, the interest rate is not constant, Regime-Switching Model is taken to fit the process of the zero-coupon bond price, and a bivariate model for interest rate and stock index return with regime-switching and dependent jump risks (MMJDMSI) is proposed. The empirical data are Dow Jones Industrial Average and S&P 500 Index from 1999 to 2013, together with US 1-Year Treasury Bond over the same period. Model parameters are estimated by the Expectation-Maximization (EM) algorithm. The likelihood ratio test (LRT) is performed to compare nested models, and MMJDMSI is better than the others. Then, European call option pricing formula under each model is derived via Esscher transformation, and sensitivity analysis is conducted to evaluate changes resulted from different parameter values under the MMJDMSI pricing formula. Finally, model calibrations are performed and implied volatilities are computed under each model empirically. In cases of in-the-money and out-the-money, MMJDMSI has either the smallest or the second smallest pricing error. Also, the implied volatilities from MMJDMSI display a volatility smile curve.

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