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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

KLIC作為傾向分數配對平衡診斷之可行性探討 / Using Kullback-Leibler Information Criterion on balancing diagnostics for baseline covariates between treatment groups in propensity-score matched samples

李珮嘉, Li, Pei Chia Unknown Date (has links)
觀察性研究資料中,透過傾向分數的使用,可以使基準變數在實驗與對照兩組間達到某種程度的平衡,並可視同為一隨機試驗,進而進行有效的統計推論。文獻中有關平衡與否的診斷,大多聚焦於平均數與變異數的比較。本文中我們提出使用KLIC(Kullback-Leibler Information Criterion)及KS(Kolmogorov and Simonov)兩種比較分配函數差異的統計量,作為另一種平衡診斷工具的構想,並針對其可行性進行探討與評比。此外,數據顯示KLIC及KS與透過傾向分數配對的成功比例呈現負相關。由於配對成功比例過低將導致後續統計推論結果的侷限性,因此本文也就KLIC及KS作為是否進行配對的一個先行指標之可行性作探討。模擬結果顯示,二者的答案均是肯定的。 / In observational studies, propensity scores are frequently used as tools to balance the distribution of baseline covariates between treated and untreated groups to some extent so that the data could be treated as if they were from a randomized controlled trial (RCT) and causal inferences could thus be made. In the past, balance or not was usually diagnosed in terms of the means and/or the variances. In this study, we proposed using either Kullback-Leibler Information Criterion (KLIC) or Kolmogorov and Simonov (KS) statistic as a diagnostic measure, and evaluated its feasibility. In addition, since low propensity score matching rate decreases the power of the statistical inference and a pilot study showed that the matching rate was negatively correlated with KLIC and KS; thus, we also discussed the possibilities of using KLIC and KS to be pre-indices before implementing propensity score matching. Both considerations appear to be positive through our simulation study.
2

男性婚姻溢酬之研究: 傾向分數配對法之應用 / Marital wage premium for male: an application of propensity score matching

林瑋 Unknown Date (has links)
在勞動市場裡可以觀察到,每個人的工資都不相同。在過去的研究裡,學者嘗試以各種人力資本變數來解釋工資率的差異。其中,在男性的工資方程式中,婚姻狀態特別受到關注,且在過去研究皆發現男性存在著婚姻溢酬。文獻上解釋婚姻溢酬的來源,主要分成三個假說,分別是家庭分工假說、選擇性假說以及雇主的偏好。 本文和過去研究不同的地方在於消除選擇性偏誤的方法。我利用傾向分數配對法使婚姻狀態變成一個隨機決定的過程。配對完,並將資料整理為追蹤資料的型態後,再估計婚姻溢酬。最後結果顯示,在利用配對方法把單一年度資料轉換為兩期的追蹤資料後,婚姻溢酬仍然相當顯著,因此本文不支持選擇性假說。但是因為追蹤資料涵蓋期間過短,因此我無法利用現有的資料區分出家庭分工和雇主的偏好這兩種效果。 / The study of determinants of individual wages is important for exploring why some individuals earn more than other individuals. In the past, numerous efforts have been devoted to explain wage differentials by various human capital variables. Marital status is also used as a control and is of interest in estimating the male’s wage regression. It is commonly acknowledged that in cross-sectional analyses, married men have higher wages than single men, other things being equal. The higher wages paid to married men compared with their single counterparts is defined as marital wage premium. There are three leading hypotheses: family role specialization, selection hypothesis and employer favoritism. This paper uses a new method called propensity score matching to estimate the male marital wage premium. Propensity score matching is used to create a quasi-experiment that makes the decision to get married become a random treatment. The principle is to match a married man to a comparable single man who is closest in terms of important characteristics. And then, I transform the matched sample into panel data where units are observed at two periods, having the unmarried man as a proxy of married man, as if he was single. Therefore, I can apply fixed effect and random effect models to the transformed data. The results show no evidence to support the selection hypothesis since after transforming the data into panel data set and applying the fixed effect model, the marital wage premium is still significant. But being limited by the short period of the quasi-panel data set, I cannot distinguish between family role specialization and employer preference.
3

傾向分數配對與確切配對之合併使用: 蒙地卡羅模擬研究與實證分析 / 無

賴致淵 Unknown Date (has links)
在觀察性研究或非隨機試驗研究中,欲探討因果效應時,研究者需要重新對觀察性研究進行設計,設計目的在於重新建立一個隨機指派受試者的機制,使其得以近似一個隨機試驗研究,這樣的研究一般稱為「類隨機試驗研究」(quasi-randomized-experiments)。 傾向分數分析即為一種設計觀察性研究的方法,在不牽涉到反應變數結果之下進行設計。本文於一個病例對照研究(case-control study)中使用傾向分數進行配對接著再進一步估計處理效果,傾向分數配對是可降低觀察性研究中的選擇性偏誤的方法,透過配對可減少實驗組與對照組間的系統性差異,使研究群體在所觀察到的控制變數分配達到相似,進而得到處理效果(treatment effect)的不偏估計,為近年廣受流行病學、經濟學以及社會學領域使用的方法之一。傾向分數本身為一個條件機率,定義為研究受試者在其所觀察到的控制變數之下,接受某處理或被指派至某特定群體的機率,估計傾向分數最常見的方法為羅吉斯迴歸。 此外,自1970年代起,配對方法(matching method)開始被使用來選取合適的實驗組與對照組並進行兩群體的比較,其中「確切配對」屬於最常使用的配對方法,過去文獻中經常可見各種配對方法的結合使用,因此,本文電腦模擬研究部份,欲比較四種情境之下「傾向分數配對」與「確切配對」結合使用的效果,分別以偏誤降低比例、信賴區間覆蓋率、均方誤衡量兩種配對方法結合使用的適合情境。結果顯示若對「與處理指派中度相關的變數」且「與反應變數高度相關的變數」,其效果最為明顯。根據結果,我們總結認為「確切配對與傾向分數配對合併使用」確實會有較好的表現,但表現的好壞也取決於確切配對的變數。實證研究部份,探討家庭結構對青少年偏差行為之影響,欲了解來自非完整家庭之青少年是否較來自完整家庭之青少年更有容易出現偏差行為。 / In observational or nonrandomized studies, treatments are not randomly assigned so that baseline differences between treated and control groups are typically observed. Without properly executed, the differences would bias the treatment effect estimates. There has been a long history of using matching to eliminate confounder bias, and inferences are made based on the matched observations. The theoretical basis for matching has been developed since 1970, and among those matching methods commonly in use, the exact matching is probably the most popular one. On the other hand, introduced by Rosenbuam and Rubin in 1983, propensity scores, the conditional probability of being exposed or treated given the observed covariates, has been a welcome alternative used to adjust for baseline differences between study groups of late. Instead of matching a treated with an untreated subject by their covariates, subjects in both treated and control groups are matched by their propensity scores. In this study, we explore the benefits of using propensity score matching together with the exact matching for adjusting for baseline differences through Monte Carlo simulations. An empirical study is also be provided for illustration.
4

企業社會責任對現金股利影響性之研究 / The impact of corporate social responsibility on cash dividends

吳昕樺, Wu, Hsin Hua Unknown Date (has links)
本研究主要探討企業社會責任與現金股利之間的關聯性,並利用傾向分數配對方法(Propensity Score Matching method)控制可能會影響落實企業社會責任的因子,再進一步探討企業社會責任本身是否對現金股利仍具有正向影響性。由於企業社會責任由許多構面所組成,我們將繼續探討企業社會責任各個構面的落實是否對股利政策具有顯著的影響效果,並將研究落實企業社會責任是否會為企業帶來保險效果。本研究利用傾向分數配對方法,根據公司的傾向分數是否相近來進行樣本的配對,藉由分析落實企業社會責任公司與其反事實樣本(其特性變數和落實企業社會責任公司極為相似但實際上未落實企業社會責任的公司)來降低選擇性偏誤與內生性問題。本研究以2007年至2016年之上市上櫃公司(不包括金融類股)為樣本,實證結果發現落實企業社會責任的公司現金股利發放較多,且企業社會責任之評分與現金股利亦呈正向影響。此外,各項構面對現金股利發放皆有正面影響,然而落實企業社會責任並無顯著保險效果。同時以傳統解決選擇偏誤問題的Heckman(1979)兩階段估計法作為傾向分數配對法之穩健性檢定,實證結果與前述結果類似。 / This research examines the impact of corporate social responsibility (CSR) on firm’s dividends and the impact between different components on dividends. (i.e. Corpo-rate Governance, Corporate Commitment, Social participation, Environmental Pro-tection). This research suggests that corporate social responsibility have positive im-pact on dividends. We also examine the insurance effect of CSR activities. In this research, we use propensity score matching method to prevent from the contamina-tion of CSR-effect and the selection bias. This research uses all listed company at stock exchange market and over the counter data which financial stocks are exclud-ed and defines the winners of Excellence in Corporate Social Responsibility Award which conferred by Common Wealth Magazine as firms with CSR during 2007 to 2016. The findings support the view of relationship between CSR and dividends is positive. Moreover, each component has positive effect on dividends, while the in-surance effect does not exist. We also use the Heckman two-stage model (1979) as robust test, and find the similar results as using propensity score matching method.
5

綜合高中分流政策對學生學習成就的影響 / Effects of comprehensive high school policy on students’ achievement: evidence from taiwan education panel survey

李敦義, Lee, Duen Yi Unknown Date (has links)
我國自1996年起開始試辦綜合高中,迄今已有十餘年。試辦綜合高中的目的在於促使我國後期中等教育能在高中、高職之外,提供另一條不同的選擇進路,俾使學生得以適性發展,學得多方面的知識,達到適性教育的目標。過去國內關於綜合高中分流政策的研究,大都集中在探討綜合高中的辦學績效和實施困難,而非該政策對學生學習成就的影響之探討。有鑑於此,本研究進一步探討:(1)哪些因素會影響國中畢業生選擇就讀普通高中和綜合高中學術導向組;(2)就讀綜合高中的學生,其學生學習成就是否優於就讀一般高中或高職;(3)綜合高中的課程分流政策是否能減少教育階層化的產生。 原始資料取自臺灣教育長期追蹤資料庫(Taiwan Education Panel Survey)公開使用版中的第一波到第四波國中追蹤樣本資料,並使用傾向分數配對法(Propensity Score Matching)探討上述三個研究目的。研究結果發現:(1)控制其它相關因素之後,過去學習成就和家庭社經背景愈佳者,愈有可能就讀普通高中及綜合高中學術導向組;(2)在學生學習成就表現上,就讀綜合高中的學生並不比就讀一般高中或高職的學生來得好;(3)綜合高中分流政策和制度性分流一樣,都會產生教育階層化現象。最後,本研究說明本研究結果對綜合高中分流政策的意涵,及提出研究建議供後續研究之用。 / Since 1996, Taiwan government launched the policy of Comprehensive High School (CHS) to relax the traditional system of curriculum tracking at the level of the senior secondary education. A number of studies and on-site evaluation reports on CHS have been made. So far, these studies and reports focused on exploring the performance of comprehensive high schools and difficulties in implementation of the policy. No evaluation of the impacts of the CHS policy on student achievement has yet been done. The purpose of this study is to examine the effects of the CHS policy on students’ achievement in the upper secondary education in Taiwan. This study attempts to answer the following research questions: (1) What factors influence junior-high school graduates’ decision on attending general high schools, and the academic track in comprehensive high schools? (2) Do students enrolling in comprehensive high schools perform better academically than those enrolling in general or vocational high schools? (3) Do curriculum tracking in comprehensive high schools enhance or reduce inequality in educational achievement? Using the data from the public released core panel data of the Taiwan Education Panel Survey (TEPS) in 2001, 2003, 2005, and 2007, this study employs the method of propensity score matching (PSM) to estimate the average treatment effect of CHS policy on student achievement. All results of PSM analysis indicate that (1) all else being equal, students with higher prior student achievement and better socio-economic backgrounds have more opportunities to enroll in an academic track, including senior high schools and the academic track in comprehensive high schools, than those with lower level of prior achievement or socio-economic backgrounds; (2) for those enrolled in comprehensive high schools, there is virtually no gain in student achievement from the CHS policy; and (3) tracking in comprehensive high schools produce inequality in educational achievement, which is similar to tracking between general and vocational high schools. Finally, the present study discusses the implications of the CHS policy and suggests directions for future research.
6

社會責任指數之加入與剔除對股東財富之影響 / The shareholder effects of social index addition or deletion

郭懿萱, Kuo, Calista Unknown Date (has links)
自1990年代中期,隨著環保、消費者權利、童工…等這些議題被廣泛檢討,越來越多人同意各別公司與整個社會是價值共享且相互依存的,若要達到共存共榮的理想,則公司必定要將社會責任融入其自身追求競爭力和商業策略的核心架構中。企業社會責任(Corporate Social Responsibility)並無公認標準,但一般泛指企業除了追求股東的利益極大化外,還必須兼顧員工、顧客、供應商、合作夥伴、社區團體、環境…等。 道瓊永續性指數(Dow Jones Sustainability Index)為現今資本市場衡量企業社會責任的標竿指數,而企業名列在被大眾認可的永續性指數上,就是企業可以傳達給利益相關者(stakeholders),表明他們注重企業社會責任的訊號之一。藉由研究企業被涵蓋在聲譽卓著的永續性指數之內是否能為股東創造價值,本論文將探討企業永續發展和企業價值之間的複雜關係。 本研究利用傾向分數配對法(Propensity Score Matching),降低進入與退出道瓊永續性指數這兩組公司間的異質性,以求得出的結果較不受公司規模、財務槓桿、產業等外在其他因素干擾。將2002至2009年間的樣本數配對後,以道瓊永續性指數作為企業社會責任之代理變數,以累積異常報酬率(Cumulative abnormal return)代表為股東創造之財富,我們追蹤資本市場對於企業進入和退出道瓊永續性指數的反應,來探討股東是否認同公司參與企業社會責任是創造價值之行為。 本研究結果顯示如下: 第一、當企業被加入道瓊永續性指數時,該企業之股東將獲得正向且顯著性的累積異常報酬率,這代表名列著名的的永續性指數是一個股東認可,且企業應追尋的目標。第二、當企業被道瓊永續性指數剔除時,該企業之股東將獲得負向但不顯著的累積異常報酬率。因此我們至少可以推論,從事企業社會責任活動,並不會破壞企業整體之價值。 / Corporate social responsibility (CSR) gradually becomes an important corporate strategy to every company in the worldwide economy. The social performance of a firm can shape the images to key stakeholders, no matter they are employees, suppliers, customers or investors, and influence decision making and relationships with the firm in the later stage. While corporations are busy engaging and enhancing CSR practices, there are few established empirical research on CSR effects and relevance in the capital markets. Hence, my thesis explores the relationship between corporate sustainability and firm value by asking whether membership on a recognized sustainability index is value generating. As stakeholders are urging that firms demonstrate their commitment to sustainability, one signal that companies can send to stakeholders to indicate that they are sustainable is membership on a recognized sustainability index. My research investigates this issue by tracing the market reaction to corporate entries and exits from Dow Jones Sustainability Index, recognized as a CSR benchmark, between 2002 and 2009. Instead of using regression models, I employ a propensity score matching (PSM) pairs design to overcome heterogeneity between different firms. My thesis highlights two main findings: a significant share price rising trend in cumulative abnormal returns (CAR) of the samples under the addition situation, suggesting that inclusion on the Dow Jones Sustainability Index (DJSI) is a goal that firms should pursue. Another is an insignificant negative stock market reaction while firms are removed from the DJSI, and I can draw from the results that, at the very least, adopting CSR doesn’t deteriorate the value of the firms. Our results suggest that the benefits of being included on the DJSI outweigh or equal to the costs associated with applying a membership on DJSI.
7

企業社會責任行為對財務績效的影響與金控銀行與獨立銀行的績效比較-配對方法的應用 / The Effects of Corporate Social Responsibility on Financial Performance and the Performance Comparisons between FHC-banks and Independent Banks-An Application of Matching Methods

張元, Chang,Yuan Unknown Date (has links)
本篇論文應用Rubin (1973)、Rosenbaum and Rubin (1983、1985a,b)所發展的配對方法(Matching Method)探討兩個議題,其一是評估企業從事社會責任行為是否可以改善績效,另一則是探討銀行加入金控後對其績效的影響。 / 針對第一個議題,我們將FTSE All-share 指數中被收錄於英國FTSE 社會責任指數的成份股定義為社會責任企業,未被收錄者定義為非社會責任企業,應用配對方法,根據特性變數是否相近為依據進行樣本配對。實證結果發現,不論使用配對前或是配對後的樣本進行分析,皆找不到社會責任企業的平均績效優於非社會責任企業的證據;相反地,部分的證據顯示社會責任企業的財務績效相對較低,因此我們的分析結果傾向支持焦點移轉假說,社會責任行為對財務績效的影響效果為負。 / 另外,我們以遠見雜誌於2006 年公佈的企業社會責任調查為基礎,將衡量企業社會責任績效的三個層面-社區參與、環境保護與財務透明,透過投資組合分析與迴歸分析來評估公司承擔社會責任與財務績效之間的關聯性。實證結果發現,第一,平均來說,公司的社會責任評分愈高,在評比結果公佈後的股票報酬愈低,兩者之間呈現負向關係;第二,公司在不同層面的社會責任行為對於股價報酬的影響具有差異性;第三、透過公司的長期財務資料發現,社會責任評分高的公司其長期平均會計績效相對較佳,但長期平均的股票報酬相對較低,表示社會責任型公司不一定是一個好的投資標的;最後,我們找不到支持社會責任行為可以做為公司績效保險的證據。本文使用各別層面的評比指標,更廣泛地評估社會責任行為對財務績效的影響,改進既有文獻中僅使用單一指標的不足之處。 / 就第二個議題而言,同樣地應用配對方法,根據銀行的特性變數是否相近為依據進行樣本篩選,利用台灣上市上櫃的銀行在2002 年第1 季至2006 年第2季的資料,我們發現在樣本配對前,平均來說,金控銀行在15 個CAMEL 績效指標的表現上皆相對較佳;樣本配對後,金控銀行除了在費用比率之外,其他的評比指標仍相對優於獨立銀行;不論使用配對前或配對後的樣本做分析,皆未出現金控銀行績效顯著較差的證據,因此,我們的實證結果偏向支持綜效假設,銀行加入金控對績效的影響效果為正向。 / 我們的研究架構與方案評估與政策衝擊分析文獻中的方法相一致,而貢獻則在於我們考慮樣本之間特性變數的差異性,進而以樣本配對的方式修正這個差異性,將有效降低既有文獻中在檢驗上述兩個議題上的選擇偏誤問題。 / In this thesis, we apply several matching methods, develop by Rubin (1973)、Rosenbaum and Rubin (1983, 1985a,b), on examing the effects of Corporate Social Responsibility (CSR) on firm financial performance (CSR-effect) and on evaluating the effects of banks being subordinated to FHC on CAMEL indicators (join-FHC effect). / For the former application, two competing hypotheses, social impact hypothesis and shift of focus hypothesis, are proposed, where the former suggests that CSR has a positive relation with performance and the latter are opposite. To ensure the CSR-effect is not contaminated by other factors or the sample is randomly drawn, we employ four matching methods, Nearest, Caliper, Mahala and Mahala Caliper to match the characteristics of the firms with CSR (CSR-firms) and without CSR (NonCSR-firms) to get rid of sample selection bias. Although the four methods yield slightly different results, to our surprised, firms engaging in CSR activities obtain lower values on the return on assets, return on equity, return on sales and earnings per share. Therefore, CSR at the very least does not improve the firm performance, supporting the shift of focus hypothesis. Engaging in CSR activities lead to more pain than gain, at least in the short run. / On the CSR topic, using a set of disaggregated social performance indicators for community participation, environmental protection and fiancail transparency from the Global Views Monthly, we examine the relationship between CSR and financial performance of TSE listing companies. Our main results show that first, scores on composite social performance indicators are negatively related to stock returns and this relationship cannot be rationalized by multi-factor models for explaining the cross-sectional variation in stock returns. Second, the effects of three disaggregated social performance indicators on stock returns are differenct among industries. Third, aggregated social performance indicator is positively related to long-term accounting performance but negatively related to long-term market performance, and thus implies that good companies are good in books, but not good investments. Finally, firms with high CSR ratings do no exhibit smaller decline of their financial performance during stagnations and thus not support the view that CSR is insurance of financial performance. / The second application, two hypotheses, synergy hypothesis and specialization advantage hypothesis, are raised too, where the former suggests that FHC-banks performer better and the latter are contrary. Above four matching methods are still used to fix the characteristics of two groups of banks in order to correct for sample selection bias. Based on after-matching samples, most of our empirical results suggest that FHC-banks, on average, outperform independent banks on most of indicators on capital adequacy, asset quality, earning ability and liquidity but not on management ability and being FHC-banks at the very least does not deteriorate the performance of banks, making our conclusion favors the synergy hypothesis and against specialization advantage hypothesis in Taiwan. / Our framework is identical to many applications of matching method such as Persson (2001), Hutchison (2004), Glick, Guo and Hutchison (2006), and are also parallel to standard medical and biological research.
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單一性別學習環境對高中女生選組行爲的影響: 基於「台灣教育長期追蹤資料庫」的反事實分析 / The Effect of Single-Sex Schooling on High School Girls’ Curriculum Tracking Selection: A Counterfactual Analysis of Taiwan Educational Panel Survey

李尋菲 Unknown Date (has links)
本研究使用「臺灣教育長期追蹤資料庫」第二波(2003)國三與第三波(2005)高二的CP追蹤數據,採用反事實模型框架下的傾向分數配對法估計單一性別環境對臺灣高中女生選組行爲(自然組/社會組)的因果效應。使用學生進入高中前的國三資料,本研究在學生因素,家庭因素和學校、班級因素三個方面充分平衡處置組(進入女校)和控制組(進入男女合校)的樣本,使配對樣本之間除了進入女校或進入男女合校之外,在以上三個方面儘可能相等,嘗試克服觀察性數據因選擇性偏誤問題對因果效應的估計帶來的阻礙。結果顯示,在進行傾向分數配對後,處置組和控制組之間達到了很好的平衡,進入女校的女生與進入男女合班的男女合校中的女生相比,女校顯著地促進了高中女生選自然組的機率,然而該效應在數學成績水平不同的女生中存在異質性,女校顯著地促進了數學成績處於高水平的女生的選擇自然組的行爲。作爲教育分流的重要組成部分,臺灣高中生選組行爲的性別隔離長期存在,選組行爲與學生未來大學科系選擇和職業選擇關係密切,自然組中低比例的女生組成顯現出隱藏的教育機會不平等。該現象長期存在的背後因素,除了學生個人因素和學生家庭背景因素帶來的影響,本研究關注學校這一角色對高中女生選組行爲的影響。 / Based on the Taiwan Educational Panel Survey’s core panel data from wave 2 (junior high school/9th grade) and wave 3 (high school/11th grade), researcher applies the propensity score analysis in counterfactual framework to study the causal effect of single-sex schooling on high school girls’ curriculum tracking (science track or humanity track) selection. Observational data always be the obstacles of making the causal analysis because it's lacking random assignment and being under threat of selection bias and unobserved variables. Using the pretreatment variables from students in 9th grade, students in the treatment group were matched with those in control groups by the individual factors, family factors and school, classroom environment factors. After matching, students come from different groups are supposed to be relatively equivalent on all the matching variables except for attending single-sex school or not. The researcher can make suitable comparison and prediction between well-matched samples. The result shows that more girls in single-sex high schools tend to choose science track. Effect of single-sex schooling is not the same among girls with different level of math scores. It benefits girls with top math performance significantly. As an important part of the educational tracking system, alternative curriculum tracking selection in Taiwan high school is worth noteworthy. The long lasting gender segregation is closely associated with students college major as well as occupation selection and it reveals the hidden educational inequality between gender. Other than focusing on the individual and family background effect on high school girls’ curriculum tracking selection, this study highlights the school effect on it.

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