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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.
1

財務市場資訊不對稱下之市場現象與參與者行為之研究

謝易霖 Unknown Date (has links)
財務市場資訊不對稱的現象已由不少學者研究, 本文利用真人實驗方法對此一議題再檢驗, 依照擁有資訊的程度分為: 完全知訊者、不完全知訊者與外部者。結果發現, 價格收斂情形與知訊者的多寡有顯著相關, 然而卻與知訊品質的高低相關性較低。成交量與價格收斂情形呈反向關係, 雖顯著但相關性有限, 我們推測對資產定價的落差雖是交易動機的原因之一,但並非僅只有此原因。市場內財富差異性亦與價格收斂有所相關, 價格收斂越好的市場, 市場吉尼係數就越小, 顯示參與者間貧富落差越小。與過去文獻差異較多是擁有較多資訊的參與者不見得有較好的利得,因此, 擁有資訊的程度不再是決定利得的唯一因素, 策略的選擇將是影響利潤的重要因素之一。 根據實驗結果, 發現限價單使用比例與期末利得有顯著的正相關, 且排名較為前面的參與者能較快學習到此一結果。本文將限價單使用比例的增減做為一策略選擇, 並利用三種強化學習模型解釋市場現象, 此三種模型皆從Roth 與Erev 的文獻中而來, 前二種模型中有二種參數: 新進因子與經驗因子, 新進因子表示前一期策略的動機對本期採同一策略動機的影響,經驗因子則表示前其策略所引發的利潤對本期策略動機的影響, 此一參數亦隱含了參與者強化學習之能力。第三種模型則多增加了參與者對利潤敏感的的測度。結果發現, 無論是此三種模型的何種參數, 在不同資訊結構的市場與不同類型的參與者間幾無差異。然而, 若以參與者利得的表現區分, 參與者對過去利潤的反應, 即經驗因子, 有顯著的差異, 說明了利潤高低與是否能從過去利潤結果學習到經驗(即強化學習能力) 有密切關係。上述三個現象說明, 參與者的行為參數在進入實驗室前就已決定了,因此利用市場環境與參與者身份將之分類比較的差異性不大, 但這樣的差異卻會影響之後的利得。故本文的結論與過去文獻不同的是, 在此實驗中決定參與者利得 多寡的不再是資訊掌握程度, 而是其學習(策略) 之能力。
2

賽局理論與學習模型的實證研究 / An empirical study of game theory and learning model

陳冠儒, Chen, Kuan Lu Unknown Date (has links)
賽局理論(Game Theory)大多假設理性決策,單一回合賽局通常可由理論證明均衡(Equilibrium)或是最佳決策,然而如果賽局重複進行,不見得只存在單一均衡,光從理論推導可能無法找到所有均衡。以囚犯困境(Prisoner Dilemma)為例,理論均衡為不合作,若重複的賽局中存有互利關係,不合作可能不是最佳選擇。近年來,經濟學家藉由和統計實驗設計類似的賽局實驗(Game Experiment),探討賽局在理論與實際間的差異,並以學習模型(Learning Model)描述參賽者的決策及行為,但學習模型的優劣大多依賴誤差大小判定,但誤差分析結果可能與資料有關(Data Dependent)。有鑑於學習模型在模型選取上的不足,本文引進統計分析的模型選取及殘差檢定,以實證資料、配合電腦模擬評估學習模型。 本文使用的實證資料,屬於囚犯困境的重複賽局(Repeated Game),包括四種不同的實驗設定,參加賽局實驗者(或是「玩家」)為政治大學大學部學生;比較學習模型有四種:增強學習模型(Reinforcement Learning model)、延伸的增強學習模型(Extend Reinforcement Learning Model)、信念學習模型(Belief Learning Model)、加權經驗吸引模型(Experience-Weighted Attraction Model)。實證及模擬分析發現,增強學習模型較適合用於描述囚犯困境資料,無論是較小的誤差或是適合度分析,增強學習模型都有較佳的結果;另外,也發現玩家在不同實驗設定中的反應並不一致,將玩家分類後會有較佳的結果。 / In game theory, the optimal strategy (or equilibrium) of one-shot games usually can be solved theoretically. But, the optimal strategies of repeated games are likely not unique and are more difficult to find. For example, the defection is the optimal decision for the one-shot Prisoner Dilemma (PD) game. But for the repeated PD game, if the players can benefit from cooperation between rounds then the defection won’t be the only optimal rule. In recent years, economists design game experiments to explore the behavior in repeated games and use the learning models to evaluate the player’s choices. Most of the evaluation criteria are based on the estimation and prediction errors, but the results are likely to be data dependent. In this study, we adapt the model selection process in regression analysis and apply the idea to evaluate learning models. We use empirical data, together with Monte Carlo simulation, to demonstrate the evaluation process. The empirical data used are repeated PD game, including four different experimental settings, and the players of the game are from National Chengchi University in Taiwan. Also, we consider four learning models: Reinforcement learning (RL) model, Extend Reinforcement learning (ERL) model, Belief Learning (BL) model, and Experience-weighted attraction (EWA) model. We found that the RL model is more appropriate to describe the PD data. In addition, the behaviors of players in a group can be quite different and separating the players into different sets can reduce the estimation errors.
3

以減少測量數為目標之無線網路定位系統 / Reducing Calibration Effort for WLAN Location and Tracking System

李政霖, Li, Cheng-Lin Unknown Date (has links)
內容感知的應用在今日已經變的越來越熱門,而位置資訊的可知也因此衍生出許多研究的議題。這篇論文提出了一套精準的室內無線網路系統名為Precise Indoor Location System (PILS)。大部分擁有良好定位精準度的定位系統都必須在事情花費許多的人力在收集大量的訊號上面,使得定位系統的變的不實用與需求過多的人力資源。在這篇論文裡,我們將目標放在減少在建置訊號地圖上的人力資源耗費並且保持住定位系統的精準度在一個可以接受的範圍。我們也提出了在資料收集上、訊號內插上、以及位置估計上的模型。另外我們也考慮了一連串連續訊號的相關度來提高準確度。無線網路訊號傳遞的特性也是我們研究的一部份,大小範圍的遮蔽包含在我們所研究的訊號傳遞現象裡面。最後我們提出了一套學習的模型來調整我們的訊號地圖,以改進因為測量數目的減少所造成的精準度下降。 / Context-aware applications become more and more popular in today’s life. Location-aware information derives a lot of research issues. This thesis presents a precise indoor RF-based WLAN (IEEE 802.11) locating system named Precise Indoor Locating System (PILS). Most proposed location systems acquire well location estimation results but consume high level of manual efforts to collect huge amount of signal data. As a consequence, the system becomes impractical and manpower-wasted. In this thesis, we aim to reduce the manual efforts in constructing radio map and maintain high accuracy in our system. We propose the models for data calibration, interpolating, and location estimation in PILS. In the data calibration and location estimation models, we consider the autocorrelation of signal samples to enhance accuracy. Large scale and small scale fading are involved in the wireless channel propagation model. We also propose a learning model to adjust radio map for improving the accuracy down caused by calibrated data reduction.

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