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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

台灣上市上櫃公司發行可轉換債券之存活分析研究 / Survival analysis for convertible bonds of listed companies in Taiwan

戴誠蔚 Unknown Date (has links)
可轉換公司債為複合式證券,除了具有債券性質外,並給予持有者於債券流通期間內行使轉換為股票之權利。以存活分析方法探討可轉債之研究尚屬少見,本論文乃以台灣上市櫃公司發行之5年期可轉債為研究資料,先整理出與公司經營有關的變數,再分別以Cox模式與再發事件之兩種邊際模型(marginal model):A-G (Anderson-Gill) 模式、PWP-TT (Prentice-Williams-Petersen)模式為研究分析方法,探討可轉債之流通時間及大量交易時間的問題。本論文並將可轉債分類為債券類型、混合類型和權益類型,且由於不同類型可轉債之流通時間有所差異,因此以其為分層條件加入模式中進行分析。研究結果發現,資產總額、總負債率、TCRI評等及董監持股率等變數,具有顯著解釋可轉債流通時間的能力,可見公司財務負債狀況與穩定性與流通期間有關;而最高差價(當月最高股價與轉換價之相對差價)、長期負債率、總負債率及股價報酬率等變數,則可顯著解釋大量交易的發生時間,表示公司財務負債狀況與股價利潤差與大量交易發生之快慢有關,其中資產總額、最高差價、TCRI評等及股價報酬率之係數均顯著為正,長期負債率、總負債率及董監持股率之係數則顯著為負。由於平均表現之存活曲線與經驗存活曲線相當接近,以Kolmogorov-Smirnov檢定多無顯著差異,顯示這些模式有不錯的配適能力;至於對個別公司估計出之存活曲線,則或有與經驗存活曲線相差較多的現象,顯示所建立的模式可對個別公司提供可轉債即將結束流通或發生大量交易之預警。 / Convertible bonds are hybrid securities that possess the properties of bonds and the right to convert bonds into shocks. Few articles employed survival analysis to analyze the characteristics of convertible bonds. To investigate the effects of the issuer’s financial information to the duration of circulation and the timing of the massive trading about convertible bonds, Taiwan’s 5-year convertible bonds were collected, and three methods of survival analysis were employed:Cox model、A-G (Anderson-Gill) model and PWP-TT(Prentice-Williams-Petersen) model. We classified convertible bonds as debt-like, equity-like, and hedge-like, and then make the classification as a stratification condition later. In summary, total Assets, total debt ratio, TCRI, and the proportion of holding share in supervisors and directors are significant variables on circulation period of convertible bonds. Apparently, the extent of debt and financial stability of issuers have significant effects on circulation period; the difference between stock price and conversion price, long-term debt ratio, total debt ratio and stock return rate contribute significantly on the timing of massive trading of convertible bonds. While the extent of debt and the return of stock hasten the hazard of the timing of massive trading. Furthermore, there are no significant differences between the survival curves evaluated at the average performance levels and the corresponding empirical survival curves, according to the results of Kolmogorov-Smirnov test. However, the differences between individual survival probabilities and overall empirical survival probabilities might be large, which indicates that the models incorporate companies’ performance overtime may provide a warning message for the termination of circulation or the timing of massive trading for a particular convertible bond.
2

再發事件之存活分析之研究 / Survival Analysis For Recurrent Event Data

王麗芬, Wang,Li-Fen Unknown Date (has links)
處理多重事件或再發事件之事件發生時間的資料時,常會以Cox模式為基礎而予以延伸,其中較適合再發事件的模式為:A-G模式、GT-UR 模式、PWP-CP 模式及PWP-GT模式。這些模式又可按照是否以發生次數為分層變數,而分為未分層模式(包含A-G模式、 GT-UR 模式),及分層模式(包含PWP-CP模式、 PWP-GT 模式)。 本論文將以改良的Cox延伸模式,包括對變異數進行修正或加入事故傾向(或隨機效果),探討公務人員升等的快慢與哪些變數有關。變異數修正方式利用穩健標準誤以解決事件之再發時間之間的相依問題;事故傾向模式則主要是以隨機效果代表無法觀察到的個體間之異質性,且同一個體的各次發生時間共享相同的異質性,並假定異質性服從某種特定分配。對於各種Cox的延伸模式,我們可比較採用穩健變異數與否對估計及推論結果的差異,以及事故傾向加入前後,估計及推論結果與模式配適上的差異。 由本論文對公務人員升等資料的分析可發現,採用變異數修正方法時,未分層的模式有較小的變異數估計值,所以顯著的變數較多,包括性別、官等、教育程度及年齡;分層模式中顯著變數則只有官等及教育程度。若假定事故傾向服從對數Gamma分配,並加入於上述四種模式中,則顯著的變數與未加入事故傾向時一致,且各模式之下均無法拒絕所有人的事故傾向同為0的假設。這種現象或許是因為我們無法取得教育程度與公務人員考試及格種類之歷史資料,也有可能是因為公務人員升等的體制健全,且法規制定嚴謹,運作也有正常的模式可循所致。
3

再發事件資料之無母數分析

黃惠芬 Unknown Date (has links)
再發事件資料常見於醫學、工業、財經、社會等等領域中,對再發資料分析研究時,我們往往無法確知再發事件發生的時間或是發生次數的分配。因此,本論文探討的是分析再發事件的無母數方法,包括Nelson提出的平均累積函數(mean cumulative function)估計量,及Wang、Chiang與Huang介紹的發生率(occurrence rate)之核函數(kernel function)估計量。 就平均累積函數估計量來說,藉由Nelson導出的變異數及自然(naive)變異數,可分別求得平均累積函數的區間估計。本文利用靴環法(bootstrap)計算出平均累積函數在不同時點的變異數,再與Nelson變異數及自然變異數比較,結果顯示Nelson變異數與靴環法算出的變異數較接近。因此,應依據Nelson變異數建構出事件發生累積次數之漸近信賴區間。 本論文亦介紹了兩個或多個母體的平均累積函數的比較方法,包含固定時點之比較與整條曲線之比較。在固定時點之下,比較方法分別為平均累積函數成對差異之漸近信賴區間及靴環信賴區間、變異數分析比較法,與排列檢定法;而整條曲線比較方法包含:類似 統計量、Lawless-Nadeau檢定。這些方法應用在本論文所採之實證資料時,所得到的檢定結論是一致的。 / Recurrent event data arise in many fields, such as medicine, industry, economics, social sciences and so on. When studying recurrent event data, we usually don’t know the exact joint or marginal distributions of the occurrence times or the number of events over time. So, in this article we talk about some nonparametric methods, such as the mean cumulative function (MCF) discussed by Nelson, and kernel estimation of the rate function introduced by Wang, Chiang and Huang. As to the estimator of MCF, we can compute the confidence interval by Nelson’s variance and naive variance. We use bootstrap method to compare the performance of Nelson variance of the estimated MCF and naive variance of the estimated MCF. The results show that Nelson variance is better than naive variance, so we should construct the confidence limits for the MCF by Nelson’s variance except when only grouped data are available. We also introduce methods for comparing MCFs, including pointwise comparison of MCFs and comparison of entire MCFs. Methods for pointwise comparing MCFs include approximate confidence limits for difference between two MCFs, analysis-of-variance comparison, permutation test, and bootstrap’s confidence limits for difference between two MCFs. Methods for comparing entire MCFs include a statistic like Hoetelling’s , and Lawless-Nadeau test. Finally, all approaches are employed to analyze a real data, and the conclusions concordance with each other.

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