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因子相關性結構模型之下合成型擔保債權憑證之評價與避險 / The Pricing and Hedging of Synthetic CDO Under Factor Copula Models林恩平 Unknown Date (has links)
近年全球市場出現一些以信用違約交換(CDS)為基礎來編列之信用指數(credit indices),如DJ iTraxx Europe與DJ CDX.NA等,而以這些信用指數為參考資產組合之合成型擔保債權憑證(Synthetic CDO)契約也定期被推出,由於其為標準化契約,故次級市場相當具有流動性,使得全球合成型擔保債權憑證無論在交易量或發行量皆成長快速。
本研究在單因子相關性結構模型之架構下,利用Hull & White (2004)所提出之機率杓斗法則(Probability Bucketing Method)建立合成型擔保債權憑證之評價模型,並於評價之外增加分券(Tranche)風險衡量指標之計算,我們發現額外得到分券之風險衡量指標僅需增加約4%的程式運算時間。本研究之評價模型同時可用於分券避險參數之求算,且不會有蒙地卡羅模擬法(Monte Carlo Simulation)之下避險參數不穩定的情形。
我們發現分券已實現之損失會使分券所面對之風險下降,而分券的信用增強(Credit Enhancement)遭受損耗則使分券所面對之風險上升,故權益分券(Equity Tranche)於契約前期所面對之信用風險大於契約後期,次償分券(Mezzanine Tranche)則是於契約後期面對較大之信用風險。關於分券避險,我們可選擇利用標的信用指數或單一資產信用違約(Single-name CDS)交換來進行避險。最後我們對分券進行違約相關性(Correlation)與違約回復率(Recovery Rate)之敏感度分析,發現權益分券的信用價差與資產違約相關性呈反向關係,而與違約回復率呈正向關係;相反的,先償分券(Senior Tranche)的信用價差則與相關係數呈正向關係,與違約回復率呈反向關係;兩參數對次償分券信用價差之影響則沒有一定的趨勢。
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百貨零售業組織平衡計分卡構面相關性之研究-以台北縣購物中心為例 / A Study on the Relationship between Perspectives of Balanced Scorecard for Retail Malls林耿毅, Lin, Keng-Yi Unknown Date (has links)
Robert Kaplan與David Norton(2004)於策略地圖一書中指出,平衡計分卡四大構面,即財務、顧客、內部流程、學習與成長,是有某種程度的相關性而連結在一起的。提升與整合無形資產,必定能改善內部流程,進而增進顧客構面與改善關係人權益。
針對此一構面相關性的課題,本研究以購物中心為例,建構百貨零售業的策略管理架構,藉由績效衡量指標的建立,實施問卷調查,找出指標重要性。接著以多變量的統計方法分析資料,驗證平衡計分卡各個構面的相關性。
研究結果發現,「學習與成長構面」顯著正向的影響「內部流程構面」;而「學習與成長構面」也顯著正向的影響「財務構面」;但「學習與成長構面」對於「顧客構面」雖然呈現正向影響,在本研究的模式下卻不顯著。另外,「內部流程構面」顯著正向的影響「顧客構面」;而「內部流程構面」對「財務構面」的影響,雖為正向但並不顯著。最後,「顧客構面」顯著正向的影響「財務構面」。
實務上的意義是,百貨公司如果要提升獲利,可以藉由學習成長構面的增進來提升內部流程構面,再藉由內部流程構面的增進來提升顧客構面,進一步由顧客構面的增進來改善財務績效。 / In the book of Strategy Maps, Robert Kaplan and David Norton delineated that the four perspectives of balanced scorecard link together in a chain of cause-and-effect relations. Enhancing and Aligning intangible assets leads to improved process performance, which, in turn, results in customer and shareholder success.
This research was based on a case study of a shopping mall in Taipei County. We established a set of performance measurement indicators and gave members of the shopping center a survey. After applying the SEM and LISREL, the results found how important those indicators were. By using multivariate analysis technique, we demonstrated the chain of causation between various perspectives of balanced scorecard.
Our findings showed that learning and growth perspective affected internal process perspective positively. Learning and growth perspective affected financial perspective positively. But learning and growth perspective could not affect customer perspective significantly. On the other hand, internal process perspective affected customer perspective positively, but could not significantly affect the financial perspective. Ultimately, we found that customer perspective affected financial perspective positively.
In practice, if a shopping center wants to raise profit by strengthening customer perspective, it can enhance learning and growth of employees to increase internal process perspective. Then, better internal process can bring out the improvement in customer perspective.
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跨國金融危機擴散效果之分析-以Copula模型為分析方法 / Analysis of transnational financial crisis contagion effect-copula approach莊旭明, Chuang, Shiu Ming Unknown Date (has links)
本篇論文主要是想探討在2008年全球金融危機發生後,美國與亞洲國家股票市場之間的相關性是否發生明顯的改變。藉由2005年至2012年美國、新加坡、台灣、日本和泰國的股票市場資料,來觀察各國股票市場的相關性是否產生不對稱的現象,首先檢定美國對其他四個國家有無產生蔓延效果,並藉由不同期間的資料來檢定蔓延效果以看出各國之間是否在極端的情況下產生尾端相關性,最後,再使用不同的關聯結構函數配適出最適合資料的模型。 / The main idea of this paper is to show whether or not that stock market between U.S and Asian country has been obviously changed after 2008 financial crisis. For the sake of observing if there is or not occurred inconsistence phenomenon in each country’s stock market, we use the information from U.S、Singapore、Taiwan、Japan and Thailand since 2005 to 2012. First, look in that if U.S has contagion affects to other four countries and, checkup the contagion effects through the information from different period to find the tail dependence in extreme situation. Finally, to dispose a model which is the most suitable for the information by using different Copula functions.
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相關性極小化投資組合在台灣股票市場之應用-以元大台灣卓越50ETF為例 / Application of minimum correlation portfolio in Taiwan stock market-Yuanta/ P-shares Taiwan Top 50 ETF蔡伯緣, Tsai, Po-Yuan Unknown Date (has links)
本研究從風險分散的角度,探討近年來廣為討論的準被動式指數策略(Quasi-passive index strategy),其中挑選三大投資組合策略--等權重(Equal Weighted Portfolio, EW)、風險平價(Naïve Risk Parity Portfolio, RP)、相關性極小化(Minimum Correlation Portfolio, MCP),實證應用於元大台灣卓越50ETF,回測基準時間從2004年1月5日起至2016年12月30日止,共計13年。在實證分析中,除了探討一般的投資組合績效結果外,文中也進一步比較文獻回顧中各式風險分散測度指標,其中包含(1)風險分散比率(Diversification Ratio, DR)、(2)集中度比率(Concentration Ratio, CR)、(3)波動性加權平均相關性(Volatility-weighted Average Correlation)、(4)赫芬戴爾指數(Herfindahl Index, Index)等對各種策略的控制成效。
本研究的實證結果如下: 相關性極小化投資組合策略(MCP)在元大台灣卓越50ETF的實證應用下,雖然成分股集中配置於某特定產業類股(即集中度比率、赫芬戴爾比率相對較高),但本策略透過「波動性加權平均相關性」顯著且有效的控制,使得成對資產的相關性極小化,最終達成風險分散的投資目標。 / This article discusses the recently most popular “Quasi-passive index strategy”, especially from risk diversification aspect. We select three major portfolio strategies, including Equal Weighted Portfolio (EW), Naïve Risk Parity Portfolio (RP), and Minimum Correlation Portfolio (MCP), and apply all of three to the Yuanta/ P-shares Taiwan Top 50 ETF in Taiwan. The back-test period of the strategy is from January 5th, 2004, to December 30th, 2016 (around 13 years). In the empirical analysis, we not only compare the performance and risk of different strategies, but also focus on a variety of the measurement of diversification, such as Diversification Ratio (DR), Concentration Ratio (CR), Volatility-weighted Average Correlation (ρ), and Herfindahl Index (HI), all of which can quantify the degree of diversification control.
In the empirical result, we find that Minimum Correlation Portfolio (MCP), applied in the Yuanta/ P-shares Taiwan Top 50 ETF, will allocate highly concentrated on some specific industry (equivalently high CR and high HI). However, this strategy significantly and efficiently controls the factor of “Volatility-weighted Average Correlation (ρ)”. Therefore, MCP can minimize the coefficient correlation between each pair asset and achieve the goal of risk diversification.
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財政結構與內生成長之跨國實證研究黃俊格 Unknown Date (has links)
內生經濟成長認為政府支出結構與收入結構均會影響恆定狀態成長率之觀點和事實是否一致呢?許多先前相關之研究需被修正,因為這些研究在政府預算限制式的設定並不完全,導致實證之結果產生偏誤。本文除了將討論忽略這些偏誤所會導致之影響外,進一步將以One-Way與TwO-Way的固定效果與隨機效果模型來進行估計,並修正先前研究所發生之問題,然後找出強力的證據來支持Barro模型(1990)所做的預測。本文的樣本資料取自東亞經濟前瞻與亞洲開發銀行,以亞洲新、舊四小龍,加上申國,共九個國家的17年時間序列資料所形成的揉合資料(pooling data)為實證對象。分析結果發現在考慮異質性與同期相關性下,若採用似無相關迴歸技巧來對One-Way固定效果模型進行估計,則:(1)不論政府是以租稅收入或是非租稅收入作為融通財源,資本性支出的增加均會提高經濟成長率,經常性支出的增加則均會對經濟成長率造成負面影響;(2)在政府以租稅收入為融通來源下,非租稅收入增加將會降低經濟成長率;若政府以非租稅收入作為融通之財源,則此時租稅收入之增加將會降低經濟成長。
〔關鍵字〕資本支出、經常支出、同期相關性(Contemporaneous correlation)、異質性(HetereSkedaStiCity)、One-Way fixed(random)effect model、Two-way fixed(random)effect model、似無相關迴歸(Seemingly unrelated regression)
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傳染性風險下的信用風險因子模型與多期連續的移轉矩陣 / The credit risk model with the infectious effects and the continuous-time migration matrix許柏園, Hsu, Po-Yuan Unknown Date (has links)
放款的利息收入雖是商業銀行主要之獲利來源, 但借貸行為卻同時使得銀行承受著違約風險。銀行應透過風險管理方法, 計算經濟資本以提列足夠準備來防範預期以及未預期損失。 另外, 若銀行忽略違約行為之間的相關性, 將有可能低估損失的嚴重性。因此, 為了在考量違約相關性下提列經濟資本, 本文由 Merton (1974) 模型出發, 以信用風險因子模型判定放款對象是否違約, 進而決定銀行面對的整體損失為何。 為簡化分析, 本文假設違約損失率 (loss given default) 為 100%。 再者, 為加強相關性, 本文亦將違約傳染性加入因子模型並比較有無傳染性效果時, 模型所計算出的損失孰輕孰重。 而在決定違約與否時, 須利用來自移轉矩陣上的無條件違約機率, 然信評機構所發布之移轉矩陣概遺漏諸多訊息, 依此, 本文以多期連續的移轉矩陣修正之並得到另一不同的無條件違約機率。 最後, 以臺灣的 537 家上市櫃公司作為資產組合, 經由蒙地卡羅模擬得到兩個因子模型的損失分配, 我們發現具有傳染性效果存在時, 預期損失和非預期損失較大且損失分配也較為右偏。 / Despite interest income from loans is a major profit contributor for commercial banks, lending inevitably makes banks bear default risks. For the sake of avoiding expected and unexpected losses, risk management methods ough to be employed by banks to meet the ecomical capital requirement. Besides, loan loss severity may very well be underestimated
if the correlation between default events is disregarded. Therefore, in order to calculate economical capital when taking default correlation into account, we start
from Merton (1974) model, and identify if loans will be in default via facor models for portfolio credit risk and portfolio losses can then be detemined. To simplify our analysis in this paper, loss given default is assumed to be 100%. To intensify correlation, default contagion is, moreover, introduced to our factor model and we investigate
which model results in larger losses as well.
When determining default, we have to utilize rating transition matrices to obtain unconditional probability of default. Transition matrices published by credit rating agencies, however, have embedded drawback of insufficient information. We correct this flaw by means of another transition matrix based on continuous-time observations and produce different unconditional probability of default. Through Monte Carlo simulation, loss distributions are calibrated respectively from the two factor models under portfolio of 537 Taiwan listed and OTC companies. We find that expected and unexpected losses are larger and loss distribution is more right-skewed when infectious effects exsit.
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品牌併購相關性與品牌個性相似度對品牌權益與購買意願之影響 / Effects of Merger Type and Brand Personality on Brand Equity and Purchase Intention in Brand Merger and Acquisition謝文豪, Hsieh, Wen Hao Unknown Date (has links)
隨著資金、市場與人才國際化的趨勢,企業面對的競爭越來越激烈,企業從單品牌策略逐漸走向多品牌策略;其中,併購品牌為最快速、控制與投資程度高的品牌組合建立方式,也是目前品牌組合建立的主要趨勢,尤其以國際大型集團發起的併購案件,近幾年於市場上更是層出不窮。然而,目前關於併購行為所產生的益處與影響,多著重於有形資產財務指標的表現,而忽略無形資產的變化,然而品牌是企業彰顯價值以及與消費者溝通的橋梁,是競爭優勢來源之一,因此,本研究欲以消費者的觀點,探討品牌併購會消費者品牌認知的影響。
本研究選定保養品牌作為研究目標,操弄「併購類型相關性」與「品牌個性相似度」等變數,探究品牌併購前後,消費者對主併品牌與被併品牌「品牌權益」與「購買意願」的變化;本研究首先進行前測,找出保養品牌個性差異小與個性差異大的品牌組合,以作為正式實驗之研究標的;接著透過實驗分組,探究受試者對這些品牌組合的反應,以得到其對品牌權益與購買意願產生的變化。
本研究結果顯示,對主併品牌而言,在併購之後,對品牌權益與消費者購買意願變化並無明顯差異,但有相關性併購優於非相關性併購、品牌個性相近組合優於品牌個性相異組合的傾向;而對被併品牌而言,在被併購之後,品牌權益與消費者購買意願變化皆有顯著提升,並且相關性併購提升程度大於非相關性併購,品牌個性相似組合提升程度亦大於品牌個性相異組合。透過本研究結果分析,發現併購活動會造成企業無形資產品牌權益與購買意願的變化,因此,企業在進行併購活動時,應將品牌納入併購活動策略考量中,同時也應注重併購品牌的相關性與品牌個性相似度,以避免對彼此的品牌受損。 / With the internationalization of capital, market and human resources, companies are facing more and more intense competitions. In order to deal with this situation, companies moves from single brand strategy to multi-brand strategy, especially the strategy of merger and acquisition (M&A), which is a fast, highly controlled and highly invested method to develop multi brands. At the same time, M&A is the most common way nowadays to apply multi-brand strategy, especially for international corporations. However, the researches about the advantages and influences of M&A have focused on tangible assets, such as financial performance, instead of focusing on intangible assets, such as brand equity and brand image, which are also important to the corporations. Brand is not only a channel for company to communicate with customers but also a source of competitive advantages. Therefore, this study wants to research how the brand merger and acquisition affects customers’ brand recognitions.
This study chooses beauty care brands as research object, and “merger type” and “brand personality” as variables. By undergoing an experiment, this study examines the changes of “brand equity” and “purchase intention” after M&A for both acquiring and acquired brands. The findings are, for the acquiring brand, there is no significant change in brand equity and purchase intention after M&A, and related M&A is better than unrelated M&A, while the similar brand personality combination is better than distinc one. As for the acquired brand, there are significant rises in brand equity and purchase intention after M&A, and just like the acquiring brand, related M&A is better than unrelated M&A, while the similar brand personality combination is better than distinc one as well.
This study’s results show that the M&A would actually affect corporation’s intangible assets, brand equity and purchase intention. Therefore, when corporations decide to implement M&A strategy, they should take “brand” in consideration. Also, corporations should pay attention on the merger type and brand personality between acquiring and acquired brand to prevent the harm on both brands after M&A.
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大投資組合異質分配假設下之信用結構商品內蘊風險分析 / The Risk Profiles of Credit-Structured Products under the Large Portfolio Assumption with Heterogeneous Distributions楊啟均, Yang, Chi Chun Unknown Date (has links)
本文延伸Hull and White (2010)之跨池因子繫聯結構模型中違約相關性之描述,藉由納入Normal Inverse Gaussian分配並允許其帶有狀態轉換之特性,我們探究信用結構式商品清償順位結構中,影響次順位信用保護層(subordination level)之因素。我們以房屋抵押擔保貸款債權憑證(MBS CDO)為例,分析資產違約相關性、資產池微粒化程度、跨池違約相關性等結構性變數如何影響分券評等之合理性及風險特徵。本文的研究結果呼應Azzalini and Capitanio(2003)中所提及採用Gaussian因子繫聯結構模型之於評價信用結構商品的缺失。我們發現增進信用資產池損失分配的之厚尾性描述,得以改善高估或低估分券信用價差的情況。 / By incorporating the Normal Inverse Gaussian distribution and allowing for regime shifts in the correlation structure of the multi-pool factor copula of Hull and White (2010), in this thesis we explorer the factors constituenting the subordination levels of credit-structured products. Using MBS CDOs as an example, we examine how model-embedded variables, such as default correlation, reference-portfolio granularity, and cross-pool correlation, affect the risk profiles of MBS CDO tranches. Our numerical results echo the findings of Azzalini and Capitanio(2003) in that correlation structure obtained under the Gaussian factor copula model may be inadequate in capturing the fact-tailed characteristic of the reference-pool loss distribution, thus can result in over/under-estimation of CDO tranche spreads.
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關於信用集中度風險的兩篇論述 / Two Essays on Credit Concentration Risk傅信豪, Fu, Hsin Hao Unknown Date (has links)
【第一篇論文中文摘要】
集中度風險於結構式商品的量化與分析:以房屋抵押貸款證券為例
"Martin and Wilde (2002)與Gordy (2003)" 針對巴塞爾協定(Basel Accords)中金融機構之投資組合所內藴之集中度風險提出了相對應的微粒化調整(Granularity Adjustment)風險量化準則,然而該模型僅止於單因子架構下探究單一信用標的集中度風險之量化。本文將其架構延用至結構式商品中,允許債權群組內之信用標的具不同區域別,我們採用Hull and White(2010)之跨池違約相關性描述,並結合Pykhtin (2004)中延拓單因子聯繫模型至多因子之方式,進而求取債權群組之單一資產集中度(Name Concentration)與區域類別集中度(Sector Concentration)風險的量化。本文以房屋抵押貸款證券(Mortgage Backed Securities, MBSs)為例,於集中度風險的考量下,藉由檢視不同風險情境下分券之損失起賠點,重新評估房屋抵押貸款證券AAA投資級分券信用評級之合理性。研究結果顯示,AAA評等之分券高度曝險於系統性風險,且於高風險情境下,標的房貸之區域集中現象擴大了違約相關性對債權群組損失分配的影響,致使AAA分券之損失起賠點得以超過其實際擔保額度(subordination)範圍。
【第二篇論文中文摘要】
美國銀行放款多角化對其報酬與風險之影響:相關性與傳染的觀點
本文目的在於分析銀行放款的多角化行為對其報酬與風險之影響。研究發現納入銀行放款投資組合相關性之考量,亦即標的資產之相關性結構以及資產間因契約關係所隱含跨投資組合之傳染途徑,將降低多角化之成效。文中透過因子模型(factor model)建構資產之報酬,同時決定其相關性結構,其中將資產間殘差項相關性作為傳染指標,進一步分析投資組合內標的資產間的平均相關係數、傳染與多角化程度間的關聯性。我們以美國銀行作為研究樣本,分別以赫芬達-赫希曼指數估算投資組合權重分配之集中度、使用組合內標的產業股票報酬資訊來計算投資組合內相關程度,接著利用標的產業與投資組合外產業間的殘差相關性來捕捉產業傳染效果,將此三項指標作為衡量多角化指標,分析其在1987年至2014年間聯貸投資組合多角化情形並試圖分析放款多角化對銀行績效之影響。透過契約關係的界定進而探討顧客傳染如何影響銀行績效。
研究發現於市場處於平穩期間(tranquil period),所有多角化指標銀行放款均呈現放款多角化程度越高越有助於提高銀行的報酬並降低其風險。然而於危機期間(turmoil period),銀行應將放款權重集中於部分產業、建構相關性較低之組合或選擇較低之傳染效果之產業作為放款的對象,用以提高銀行績效。隱含在危機期間銀行應該選擇適度之多角化策略,若僅以赫芬達-赫希曼指數作為多角化之衡量將顯示危機期間越集中越有助於銀行的表現,此舉將造成解釋上的偏誤。說明於投資組合多角化的衡量上,不該忽略由相關性結構所引發之集中度風險。 / 【Essay I】
Quantification and Analysis of Concentration Risk in Structured Products: the Case of Mortgage Backed Securities
Granularity adjustments, introduced by Martin and While (2002) and Gordy (2003), allow one to quantify the concentration exposures of credit portfolios due to imperfect diversification. However, they focus solely on name concentrations under an Asymptotic Single Risk Factor (ASRF) framework. In this study, by adapting the multi-pool correlation structure of Hull and White (2010) under the multi-factor setting of Pykhtin (2004), we derive quantitative measures of name and sector concentration that facilitate subsequent analysis of the risk profiles embedded in Mortgage Backed Securities (MBSs). Under different stress scenarios, we examine the impacts of concentration exposures on the internal credit enhancements, in particular, the AAA tranche attachment points. We show that, under severe market conditions, the presence of sector concentrations in the underlying mortgage pools can further amplify the effects of default correlation on the portfolio loss distributions. As a direct consequence, the predetermined subordination level determined by the assignment of tranche attachment points can be exceeded.
【Essay II】
How Loan Portfolio Diversification Affects U.S. Banks’ Return and Risk: Correlation and Contagion Perspectives.
In this paper we investigate how loan portfolio diversification affects the banks’ return and risk. We argue that, the dependence structure of bank loan portfolios, namely, the correlation structure among loan assets and the presence of contagion channels due to contractual relationships across the border of portfolio, contributes to the costs of diversification. Under the factor model framework, we derive a theoretical model to depict the asset returns and their dependence structure. Based on data of US bank loans collected from 1987-2014, our empirical study employs HHI, intra-portfolio correlation, and contagion as proxies for diversification to examine how loan portfolio diversification affects the banks’ profitability and riskiness. In addition, contractual relationships are identified and we investigate how customer contagion affects the bank’s performance. We find that all diversification measures exhibit a positive effect on the performance of U.S. banks during tranquil periods. However, for turmoil periods, banks with loan portfolios of more concentrated weight distributions, lower intra-portfolio correlation, or lower consumer contagion effects would have improved returns and reduced risk. In other words, during crisis, banks should choose an appropriate concentration strategy rather than focus on selected industries as determined solely by the HHI.
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中文名詞多義性與詞彙認知歷程 / Multiple Senses of Mandarin Chinese Nominals: Implications for Lexical Access林千哲, Lin, Chien-Jer Charles Unknown Date (has links)
本論文以語意學、認知語言學及心理語言學的觀點,探討中文名詞的多義現象。本篇論文討論詞彙多重意義的語言及心理語言表徵,並研究詞義如何在心理詞彙庫中被擷取。
文中藉由認知語言學者Tuggy(1993)所提出的認知語意架構,及詞彙語意學中「同形異義詞(homonymy)」、「一詞多義(polysemy)」及「模糊意義(vagueness)」等觀念之區辨,探索詞義之本質。本文所談之意義(sense)根據Ahrens(1999)之定義有以下三個特性:(1)意義非轉喻(metonymy)或部分/全體(meronymy)之延伸,但可以是隱喻性延伸;(2)意義之間的延伸關係無法由在同類名詞中直接以規律獲得;(3)除非特意,一詞的不同意義不會在同一語境中同時出現。
針對詞彙辨識歷程的語意效應,本論文有三大研究主題--意義數目效應、意義相關性效應及相對意義頻率效應。各效應之預測如下:「意義數目效應」認為意義數目較多的詞彙在詞彙判斷作業(lexical decision tasks)中比較容易辨識;「意義相關性效應」認為當一個詞的意義之間的相關性較高時,該詞的辨識時間亦會較快;「相對意義頻率效應」則認為一個詞意義之間頻率差異程度越小,該詞越有歧義之特質,也因此越容易辨識。
本研究旨在以實證方式探討這些語意向度在詞彙辨識歷程中所扮演的角色。由受試者提供200個中文名詞的意義並決定意義間的相關性;進行電腦詞彙判斷作業,得到辨識每個詞所需的反應時間;再由統計考驗反應時間來驗證各效應。
本研究結果發現只有「意義數目效應」達顯著水準,意義數目較多的詞彙在詞彙判斷作業中比較容易辨識。此一效應支持心理詞彙庫的隨機觸接模型(random access model)及平行觸接模型(parallel access model)並駁斥「序列搜尋模型(serial access model)」。 / This thesis studies the multiple senses of Chinese nominals from semantic, cognitive linguistic, and psycholinguistic viewpoints. It discusses the linguistic and psycholinguistic representations of a word's multiple senses, and the access of these senses in the mental lexicon.
The nature of lexical meaning is examined by discussing lexical semantic notions such as homonymy, polysemy, and vagueness, and by introducing Tuggy's (1993) cognitive linguistic representation of a word's multiple lexical meanings. The "senses" of a word are defined according to the lexical semantic theory of Ahrens (1999) as having three properties: (1) A sense is not an instance of metonymic or meronymic extension, but may be an instance of metaphorical extension. (2) The extension links between two senses cannot be inherited by a class of nouns. (3) Senses cannot appear in the same context (unless the complexity is triggered).
This thesis specifically looks into three semantic effects on word recognition, including the word's number-of-sense (NOS) effect, the effect of sense relatedness, and the effect of relative sense frequency. The predictions of these effects are as follows: The NOS effect predicts that words with more senses are recognized faster than those with fewer senses. The effect of sense relatedness predicts that words with more closely related senses are easier to recognize than those with distantly related senses. The effect of relative sense frequency predicts that words with equal sense frequencies are more easily recognized than words with unequal sense frequencies.
This research aims at empirically verifying these three effects during the recognition of isolated lexical items. Subjects generate the senses of 200 Chinese nominals, and rate the relatedness among these senses. Lexical decision tasks are conducted to obtain the reaction times required to recognize each stimulus item. The semantic effects are verified by comparing the reaction times of different groups of experimental stimuli.
The experimental results confirm only the NOS effect, giving support to the random and parallel access models of lexical access, and refuting the serial access model of the mental lexicon.
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