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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.
21

製造業服務化轉型模式之研究 -以台達集團中達電通客戶為例 / Research on the transformation of servitization for a manufacturing corporate–A case study on the Customers of Delta GreenTech (a Delta Group Company)

游文人 Unknown Date (has links)
2008年全球金融海嘯之後,製造業隨著產品的生產變成大批量定制方式,產品的利潤空間越來越受到擠壓,而服務價值所佔的比重需求越來越大,因此服務的增值變成傳統製造業所追求的重點,而逐漸形成製造與服務相融合的新產業形態-服務型製造。服務型製造商向客戶提供的不僅僅是產品,還包括產品的服務,或整體解決方案,也包括圍繞產品生產的各類服務。 透過本研究所設計中國大陸製造業服務化問卷調查,收集到 205 家企業總經理或總經理指定的發言人的意見。以產業組織理論中著名的「結構-行為-績效模型(Structure-Conduct-Performance Paradigm, SCP)」理論,做為製造業服務化的模型,並以結構方程模型(SEM)作為實證工具,檢驗五個假說: H1:製造業環境因素影響製造業服務化需求程度 H2:市場結構集中度愈大,製造業服務化需求程度愈小 H3:企業愈重視製造業服務化,其品牌形象則愈高 H4:製造業服務化程度愈高,則銷售業績會提高 H5:企業品牌形象愈高,則銷售業績會提高 實證結果顯示H1及H4不成立,而H2、H3及H5成立。由假說二成立顯示市場結構和製造業服務化之間存在負向關係,意即市場集中度愈小的廠商愈有傾向採行製造業服務化,而影響是否採行製造業服務化的因素。假說三及假說五的成立說明製造業服務化對銷售業績並未有直接關連,而是透過影響品牌形象後而增加銷售業績,因此存在著間接關係。 而造成製造業服務化與經營績效的因果關係之關鍵因素,本研究實證指出產品複雜度為市場結構構面中影響最大的因素;製造業服務化構面則以品牌行銷影響力最大,至於品牌形象構面因素中以公司形象最具影響力;而業績銷售構面則以營業淨利及營業額成長同樣重要。
22

電磁波問題を対象としたマルチフィジックストポロジー最適化 / デンジハ モンダイ オ タイショウ ト シタ マルチフィジックス トポロジー サイテキカ

野村, 壮史 24 March 2008 (has links)
Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(工学) / 乙第12205号 / 論工博第3994号 / 新制||工||1439(附属図書館) / 26277 / UT51-2008-C975 / (主査)教授 吉村 允孝, 教授 吉田 英生, 教授 田畑 修 / 学位規則第4条第2項該当
23

台北市公共運輸旅運行為之研究 / A Study on the Travel Behavior of Public Transportation in Taipei City

莊畫晴, Chuang, Hua-Ching Unknown Date (has links)
台北市政府長期推廣公共運輸發展,自民國98年至104年期間增加延長四條捷運路線,但其公共運輸市占率僅從34.1%微幅提升至37.4%,仍無法突破四成,顯示捷運里程數增加對搭乘使用率之提升助益有限,且與台北市交通局所期待市占率目標值有顯著落差。因此,本研究欲經由目前台北市民眾使用公共運具之情形,探討公共運輸市占率無法提升之背後原因,釐清影響旅運者搭乘公共運輸工具之環境因素,以利提升公共運輸市占率之目標。 首先,透過文獻回顧瞭解都市公共運輸旅運環境之組成,而良好旅運環境建構目的係協助旅運者順利完成都市生活所需活動,其中,硬體層面包含:人行步道系統、自行車道系統、道路系統與公共運輸系統所構成之硬體旅運環境,而軟體範疇含:即時訊息平台、遠端交通資訊控制中心及路況通報中心,旨在利用科技技術進行旅運品質管理,促使優化旅運環境。此外,為瞭解台北市旅運者搭乘公共運輸之特性,彙整影響公共運輸旅運環境因素為:「搭乘安全性之考量」、「無障礙性之設計」、「乘車環境之舒適度」、「運輸系統間之機動性」、「交通訊息通報之即時性」、「準確性之要求」以及「到達目的地之可及性」,這七大公共運輸旅運環境因素影響旅運者對於公共運具之選擇,並以這七大公共運輸旅運環境因素作為公共運輸環境各層面因素量表之設計基礎,進行問卷設計與實證分析。 本研究設定之研究對象為居住於台北市且曾經使用公共運具之民眾,問卷發放期間為民國106年3月1日至3月15日,最後共回收436份樣本,隨即透過結構方程式之雙因素模式進行實證分析,結果得知:當旅運者以捷運為交通運具之旅運決策時,會以七大公共運輸旅運環境因素進行整體性之考量,亦特別重視「可及性」特殊因素之考量。又,當旅運者以公車為交通運具之旅運決策時,針對整體旅運環境進行思考,「機動性」及「可及性」之特殊因素亦為決策重點。透過實證分析可瞭解旅運者搭乘公共運輸之行為意向及實際旅運需求,用以擬定公共運輸環境改善與整合策略,其策略包含:1.公共運輸環境改善策略:研擬道路空間管理、舒適的人行空間、安全候車空間及場站通用設計等面向之規劃策略,以期能藉由實質規劃策略提升公共運輸硬體層面之環境組成;2.公共運輸資源整合策略:研擬公共運輸系統之串聯、即時訊息管理等路網及軟體面向之規劃策略,藉此強化公共運輸軟體層面之應用,並提升公共運輸之旅運效率;3.相關配套措施研擬,旨在促使前述公共運輸環境改善與資源整合之規劃策略得以具體落實,形塑優善之公共運輸旅運環境,進而提升公共運輸市占率。
24

Analysis of the Quantum Heat Transport under Non-Perturbative and Non-Markovian Conditions: The Hierarchical Equations of Motion Approach / 非摂動・非マルコフ環境下における量子熱輸送の解析:階層型運動方程式によるアプローチ

Kato, Akihito 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20194号 / 理博第4279号 / 新制||理||1615(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 谷村 吉隆, 教授 林 重彦, 教授 松本 吉泰 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
25

堰型構造物周辺の河床変動予測手法に関する研究

太田, 一行 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20345号 / 工博第4282号 / 新制||工||1663(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 中川 一, 教授 藤田 正治, 准教授 川池 健司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
26

Studies on linear systems and the eigenvalue problem over the max-plus algebra / Max-plus代数上の線形方程式系と固有値問題に関する研究 / Max-plus ダイスウジョウ ノ センケイ ホウテイシキケイ ト コユウチ モンダイ ニカンスル ケンキュウ

西田 優樹, Yuki Nishida 22 March 2021 (has links)
Max-plus代数は,実数全体に無限小元を付加した集合に,加法として最大値をとる演算,乗法として通常の加法を考えた代数系である.本論文では,max-plus線形方程式に対するCramerの公式の類似物を用いて,線形方程式の解空間の基底が構成できることを示した.さらに固有値問題に関連して,max-plus行列の固有ベクトルの概念を2通りの観点から拡張した. / The max-plus algebra is the semiring with addition "max" and multiplication "+". In the present thesis, the author gives a combinatorial characterization of solutions of linear systems in terms of the max-plus Cramer's rule. Further, the author extends the concept of eigenvectors of max-plus matrices from two different perspectives. / 博士(理学) / Doctor of Philosophy in Science / 同志社大学 / Doshisha University
27

多層次結構方程式模型在大型資料庫上的應用 / Applying Multilevel Structural Equation Modeling to a Large-Scale Database

李仁豪, Li,Ren Hau Unknown Date (has links)
本研究的主要目的是藉由實徵的PISA資料庫資料將多層次結構方程式模型的方法學介紹到台灣的教育領域。多層次結構方程式模型適合應用在大型且具階層或巢狀結構的資料,可以解決因群集性抽樣設計所導致的樣本點相依的問題。 本研究中包含三個小研究。在研究一中,實徵的資料經由多層次結構方程式模型步驟化的分析,並與傳統的結構方程式模型的分析結果相互比較。一共有五個構念及其測量指標從PISA 2003資料庫中被選取來建構多層次結構方程式模型。樣本包含948個學校共26,884位15歲來自加拿大的學生。研究結果顯示某些結構係數的正負向關係在組內層次與組間層次是十分不同的,這也彰顯出多層次結構方程式模型與傳統結構方程式模型比較下的價值。研究一的發現指出,在數學興趣與數學工具性動機控制的條件下,教師的支持對學生的數學成績及數學自我效能在組間層次並無效果,但教師的支持對學生的數學自我效能在組內層次具有正向顯著的效果。此外,除了在組間層次上數學興趣對數學成績有顯著的負向效果以及數學工具性動機對數學自我效能沒有顯著效果外,數學興趣與數學工具性動機對數學成績及數學自我效能具有顯著的正向效果。另外,數學成績對數學自我效能具有很大的效果,特別是在組間層次。 在研究二中,藉由評估跨越不同層級二樣本大小(即120、240、360、480、600、720、840、948個學校)時的模式適配度及參數估計值的穩定性,來決定一個最小較佳的層級二樣本數相對於層級二估計參數數目的比值。研究結果顯示,該比值大約至少8:1是較可以被接受的結果。在研究三中,藉由多群組多層次結構方程式模型進行跨國家的比較。根據研究二的較佳最小比例以及亞洲國家在PISA 2003資料庫中有限的層級二樣本數,一個將焦點集中在數學興趣對數學成績的不同層次預測關係之新多層次結構方程式模型被提出。由再次隨機取樣的加拿大145所學校作為西方國家的代表樣本,而由只有143所學校的日本樣本作為東方國家的代表。研究結果顯示,跨越加拿大與日本樣本,在任一層級中出現十分不同的預測效果。數學興趣對數學成績的預測效果在加拿大樣本中的兩層級皆是正向地顯著,但在日本樣本中卻都是負向地顯著。這意謂著未來某些重要的教育及心理學變項之間關係的跨國研究應該在被重視。 / The main purpose of this research was to introduce multilevel structural equation modeling methodology to Taiwan education field by applying empirical example from PISA 2003 database. Multilevel structural equation modeling was suitable to be applied to the large-scale and hierarchical or nested data structure. It could solve the problem of dependency among sample units resulted from clustered sampling design. There were three studies in the research. In study one, the empirical data dealt with multilevel structural equation modeling analysis was undertaken step by step and compared with conventional structural equation modeling analysis. There were five constructs and their measurement indicators from PISA 2003 database mapped to form the multilevel structural equation model. The sample was 948 schools with 26884 15-year-old students from Canada. The result showed the valences of some structural coefficients were quite different in between-level and within-level structural equation models, which characterisized the value of multilevel structural equation modeling when compared with the outcomes from conventional structural equation modeling analysis. The findings of study one indicated that teacher support had no effect on students’ mathematics grades and mathematics self-efficacy in between-level part but had a significant positive effect on mathematics self-efficacy in within-level part when both interest in mathematics and instrumental motivation to mathematics grades were considered in the model. Besides, interest in mathematics and instrumental motivation had positive effects on mathematics grades and mathematics self-efficacy except for negative effect from interest in mathematics to mathematics grades and no effect from instrumental motivation to mathematics self-efficacy in between-level part. In addition, mathematics grades had great influences on mathematics self-efficacy, especially in between-level part. In study two, a better minimum ratio of the number of level-2 units relative to the number of parameter estimates in between-level part was searched by evaluating the model-fit and stability of parameter estimates across several Canada samples with 120, 240, 360, 480, 600, 720 ,840, and 948 schools. The result showed that the ratio at least about 8:1 was appreciated. In study three, cross-national comparisons were processed by multiple group multilevel structural equation modeling. Based on the better minimum ratio from study two and limited level-2 sample sizes from Asian countries in PISA 2003, a new multilevel structural equation model was proposed focusing on the structural coefficient of mathematics grades regressed on interest in mathematics in each level. A random resampling Canada sample with 145 schools was served as the representative of the West nations and the Japan sample with only 143 schools was on behalf of the East nations. The result showed that quite different predictive effect in either level across the Canada sample and the Japan sample. The predictive effects of the interest in mathematics to mathematics grades were positively significant in the Canada sample in each level but were negatively significant in the Japan sample in each level, which implied that cross-national studies in some important relationships among educational and psychological variables should be emphasized in the future.
28

台灣地區貨幣需求與股市成交量共積關係之研究 / The research of the cointegration relationship between money demand and stock trading volume - the case of Taiwan

李博遠, Li, Po-Yuan Unknown Date (has links)
傳統貨幣需求函數的估計,使用的影響因素包括物價、所得及利率。但是近年股市的蓬勃發展,對貨幣需求造成了一定程度的影響。 Friedman 就股市對貨幣需求的影響提出 4 大效果,分別是交易效果、資產組合調整效果、財富效果及替代效果。其中替代效果為負,其他的效果為正。然而並非只有股市會對貨幣需求造成影響,貨幣需求同樣會影響股市。本文採用 Johansen Procedure 估計法,首先建立一般的貨幣需求模型,使用的雙變數包括貨幣需求、物價、所得及利率,實證結果確定這些變數存在 2 條共積關係,一是貨幣需求共積方程式,一是物價共積方程式。然後我們將股市成交量放入,同樣確定這些變數間具有 2 條共積關係。 Johansen Procedure 有 5 種模型,分別適用於不同的情況,我們要事先由資料來判斷使用哪一個模型並不容易,因此本文採用了多項標準,包括共積係數符號及其大小、向量誤差修正模型誤差項常態性與序列相關檢定、重要統計值(RSS、AIC、SC)等,用來作為選擇最適模型的依據。經由實證結果我們發現,不論是否加入股市成交量,模型三都是最適當的模型,也就是資料有不為零的平均數與線性趨勢,但共積方程式只有截距項。 就貨幣需求共積方程式殘差對各變數的影響來看,M1A 與 M1B 的連續增加,都會使股市成交量擴大,而 M1B 的連續增加還會形成物價上漲的壓力。而就物價共積方程式殘差對各變數的影響來看,解釋上較不容易。這可能是因為台灣地區物價長期處於穩定,加上台灣股市受到心理及消息面的影響性很大,要用總體變數作一個完整的解釋並不十分容易。雖然如此,貨幣市場與股票市場間的互動仍然極具有研究價值。 / Traditionally, when estimating the money demand, we use price index, income, and interest rate as its influcing factors. But the stock market that is booming these years has made certain influence on money demand. Milton Friedman pointed out that there are 4 effects that stock market can influcnce money demand. They are trading effect, portfolio reconstruction effect, wealth effect, and subsitution effect. Among these effects, subsitution effect has negative influence on money demand and other 3 effects have positive influence on mondy demand. However, not only does the stock market has influence on mondy demand, money demand also has influence on stock market. In my thesis, I applied Johansen Procedure estimation method. First, I established a traditional model on money demand. The variables I used including money demand, price index, income, and interest rate. From the empirical outcome we are sure that there are 2 cointegration equations among these variables.One is the money demand cointegration equation and the other is the price cointegration equation. Next we add the stock trading volume to the model. We also make sure that there are 2 cointegration relationships among them. There are 5 models in Johansen Procedure estimation method, and they are applied in different situations. It is not easy to decide which model to apply in advance. So in the thesis, we used many criteria, including the value and the sign of the coefficients, the the serial correlation and the normality test of the residuals from the vector error correction model, and important statistics(RSS, AIC, SC) to decide which model to apply. According to the empirical outcome, whether stock trading volume is included, model 3, which is there are means and linear trend in data but the cointegration equation only has intercept is the proper model we selected. About the residuals from the money demand cointegration quation's influence on variables, we find that the continuous increase in M1A and M1B will make enlarge the stock trading volume. Besides, the coutinuous increase in M1B will cause the price to raise. And about the residuals from the price cointegration equation's influence on variables, it is a little bit difficult to interpret. Maybe it is because the price is very stable in Taiwan and the stock market in Taiwan is affected by psychology side and information side easily. So it is not easy to use the macro economic variables to interpret fully. Althought it is the case, the interaction between the money market and the stock market still worth researching.
29

臺灣工業產品出口供需之實證分析——聯立方程式分析法的應用

余吉政, Yu, Ji-Zheng Unknown Date (has links)
第一節為研究之動機與目的, 說明何以會撰寫本文。第二節為研究的方法: 內就1.單 一方程式與聯立方程式分析法之比較; 2.商品分類之應用; 3.資料之收集與編制。 第二章為理論模型之探討, 分成三節, 第一節為前人研究所用模型之回顧; 第二節為 本文所用模型之設立, 分成出口需求函數與出口供給函數, 由二條方程式之聯立分別 估計出臺灣出口需求的所得彈性, 相對價格彈性, 競爭價格彈性以及臺灣出口供給的 所得彈性、生產彈性; 第三節討論本聯立方程式模型之認定問題, 是否能滿足秩條件 及階條件。 第三章為實證分析, 把臺灣出口之工業產品依中華民國進出口貨物分類表第十六版之 分類法, 對第二類至第八類產品依次作實證分析。 第四章結論: 提出著者之建議, 說明本文之缺失, 以及應如何補救。
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Consumption Euler Equation: The Theoretical and Practical Roles of Higher-Order Moments / 消費尤拉方程式:高階動差的理論與實證重要性

藍青玉, Lan, Ching-Yu Unknown Date (has links)
本論文共分三章,全數圍繞在消費尤拉方程式中,消費成長的高階動差在理論與實證上的重要性。分別說明如下: 本論文第一章討論消費高階動差在實證估計消費結構性參數之重要性。消費尤拉方程式是消費者極大化問題的一階條件,而自Hall (1978)起,估計消費結構參數如跨期替代彈性時,也多是利用這個尤拉方程式所隱涵的消費動態關係,進行估計。但是由於消費資料存在嚴重的衡量誤差問題,實證上多將尤拉方程式進行對數線性化,或是二階線性化後進行估計。 然而前述一、二階線性化,固然處理了資料的衡量誤差問題,卻也造成了參數估計上的近似誤差(approximation bias)。其原因來自於線性化過程中所忽略的高階動差實為內生,而與迴歸式中的二階動差相關。這使得即便用工具變數進行估計,仍然無法產生具有一致性的估計結果。這當中的原因在於足以解釋二階動差,卻又與殘差項中的高階動差直交的良好(valid)的工具變數無法取得。 我們認為在資料普遍存在衡量誤差的情況下,線性化估計尤拉方程式不失為一可行又易於操作的方法。於是我們嘗試在線性化的尤拉方程式中,將高階動差引入,並檢視這種高階近似是否能有效降低近似誤差。我們的模擬結果首先證實,過去二階近似尤拉方程式的估計,確實存在嚴重近似誤差。利用工具變數雖然可以少部份降低該誤差,但由於高階動差的內生性質,誤差仍然顯著。我們也發現,將高階動差引入模型,確實可以大幅降低近似誤差,但是在偏誤降低的同時,參數估計效率卻也隨之降低。 高階動差的引入,除了降低近似偏誤外,卻也必須付出估計效率降低的代價。我們因此並不建議無限制地放入高階動差。則近似階次選取,乃為攸關估計績效的重要因素。本章的第二部份,即著眼於該最適近似階次選取。我們首先定義使參數估計均方誤(mean squared error, MSE)為最小的近似階次,為最適近似階次。我們發現,該最適階次與樣本大小、效用函數的彎曲程度都有直接的關係。 然而在實際進行估計時,由於參數真值無法得知,MSE準則自然無法作為階次選取之依據。我們於是利用目前在模型與階次選取上經常被使用的一些準則進行階次選取,並比較這些不同準則下參數估計的MSE。我們發現利用這些準則,確實可以使高階近似尤拉方程式得到MSE遠低於目前被普遍採用的二階近似的估計結果,而為估計消費結構參數時更佳的選擇。 本論文第二章延續前一章的模擬結果,嘗試利用消費高階動差間的非線性關係,進一步改善高階近似消費尤拉方程式的估計表現。由第一章的研究結果,我們發現高階近似估計確有助大幅降低近似誤差,但這其中可能產生的估計效率喪失,卻是輕乎不得的。這個效率喪失,很大一部份來自於我們所使用的工具變數,雖然可以有效掌握消費成長二階動差的變動,但是當這同一組工具變數被用來解釋如偏態與峰態等這些更高階動差時,預測力卻大幅滑落。這使待得當我們將這些配適度偏低的配適後高階動差,放到迴歸式中進行估計時,所能提供的額外情報也就相當有限。而所造成的共線性問題,也自然使得估計效率大幅惡化。 於是在其他合格的工具變數相對有限的情況下,我們利用高階動差間所存在的均衡關係,將原來的工具變數進行非線性轉換,以求得對高階動差的較佳配適。由於消費動差間之關係,尚未見諸相關文獻。於是我們首先透過數值分析,進一步釐清消費高階動差間之關係。這其中尤為重要的是由消費二階動差所衡量的消費風險,與更高階動差間之關係。因為這些關係將為我們轉換工具變數之依據。 我們發現與二階動差相一致地,消費者對這些高階動差之預期,都隨其財富水準的提高而減少。這隱涵消費風險與更高階動差間之正向關係。更進一步檢視消費風險與高階動差間之關係也發現,二者間確實存在非線性之正向關係。而這也解釋了何以前一章線性的工具變數,雖可適切捕捉消費風險,但對高階動差的解釋力卻異常薄弱。 利用這些非線性關係,我們將原始的工具變數進行非線性轉換後,用以配適更高階動差。透過模擬分析,我們證實了這些非線性工具變數,確實大幅改善高階近似尤拉方程式的估計表現。除了仍保有與線性工具變數般的一些特性,諸如隨樣本的增加,最適近似階次也隨之增加之外,相較於線性工具變數,非線性工具變數可以在較低的近似階次下,就使得估計偏誤大幅下降。在近似階次愈高估計效率愈低的情況下,這自然大幅度地提高了估計效率。比較兩種工具變數估計結構數參數所產生的MSE也證實,非線性工具變數確實有遠低於原始線性工具變數的MSE表現。 然而我們同時也發現,利用非線性工具變數估計,若未適當選擇近似階次,效率喪失的速度,可能更甚於線性工具變數時。這凸顯了選擇近似階次的重要性。於是我們同樣檢視了前述階次選擇準則在目前非線性工具變數環境下的適用性。而總結第一、二章的研究結果,我們凸顯了高階動差的重要性,確實助益重要消費結構參數估計。而利用過去尚未被討論過的高階動差間非線性關係,更可大幅度改善估計績效。 本論文的最後一章,則旨在理論上建立高階動差的重要性。我們在二次式的效用函數(quadratic utility function)設定下,推導借貸限制下的最適消費決策。二次式的效用函數,由於其邊際價值函數(marginal value function)為一線性函數,因此所隱涵的消費決策,具有確定相等(certainty equivalence)的特性。這表示消費者只關心未來的期望消費水準,二階以上的更高階動差,都不影響其消費決策。然而這種確定相等的特性,將因為借貸限制的存在而不復存在,而高階動差的重要性也就因此凸顯。 我們證明,確定相等特性的喪失,其背後的理論原因在於,借貸限制的存在,使得二次式效用函數的邊際價值函數,產生凸性。消費者因而因應未來的不確定性,進行預防性儲蓄。透過分析解的求得,我們也得以進一步分析更高階動差的對消費決策的理論性質。同時我們也引申理論推導的實證意涵,其中較重要者諸如未受限消費者因預防性儲蓄行為所引發的消費過度敏感性現象,實證上樣本分割法的選取,以及高階動差的引入模型。 / The theme of this thesis seeks to explore the importance of higher-order moments in the consumption Euler equation, both theoretically and empirically. Applying log-linearized versions of Euler equations has been a dominant approach to obtaining sensible analytical solutions, and a popular choice of model specifications for estimation. The literature however by now has been no lack of conflicting empirical results that are attributed to the use of the specific version of Euler equations. Important yet natural questions whether the higher-order moments can be safely ignored, or whether higher-order approximations offer explanations to the stylized facts remain unanswered. Such inquires as in the thesis thus can improve our understanding toward consumer behaviors over prior studies based on the linear approximation. 1. What Do We Gain from Estimating Euler Equations with Higher-Order Approximations? Despite the importance of estimating structural parameters governing consumption dynamics, such as the elasticity of intertemporal substitution, empirical attempts to unveil these parameters using a log-linearized version of the Euler equation have produced many puzzling results. Some studies show that the approximation bias may well constitute a compelling explanation. Even so, the approximation technique continues to be useful and convenient in estimation of the parameters, because noisy consumption data renders a full-fledged GMM estimation unreliable. Motivated by its potential success in reducing the bias, we investigate the economic significance and empirical relevance of higher-order approximations to the Euler equation with simulation methodology. The higher-order approximations suggest a linear relationship between expected consumption growth and its higher-order moments. Our simulation results clearly reveal that the approximation bias can be significantly reduced when the higher-order moments are introduced into estimation, but at the cost of efficiency loss. It therefore documents a clear tradeoff between approximation bias reduction and efficiency loss in the consumption growth regression when higher-order approximations to the Euler equation is considered. A question of immediate practical interest arises ``How many higher-order terms are needed?'' The second part of our Monte-Carlo studies then deals with this issue. We judge whether a particular consumption moment should be included in the regression by the criterion of mean squared errors (MSE) that accounts for a trade-off between estimation bias and efficiency loss. The included moments leading to smaller MSE are regarded as ones to be needed. We also investigate the usefulness of the model and/or moment selection criteria in providing guidance in selecting the approximation order. We find that improvements over the second-order approximated Euler equation can always be achieved simply by allowing for the higher-order moments in the consumption regression, with the approximation order selected by these criteria. 2. Uncovering Preference Parameters with the Utilization of Relations between Higher-Order Consumption Moments Our previous attempt to deliver more desirable estimation performance with higher-order approximations to the consumption Euler equation reveals that the approximation bias can be significantly reduced when the higher-order moments are introduced into estimation, but at the cost of efficiency loss. The latter results from the difficulty in identifying independent variation in the higher-order moments by sets of linear instruments used to identify that in variability in consumption growth, mainly consisting of individual-specific characteristics. Thus, one major challenge in the study is how to obtain quality instruments that are capable of doing so. With the numerical analysis technique, we first establish the nonlinear equilibrium relation between consumption risk and higher-order consumption moments. This nonlinear relation is then utilized to form quality instruments that can better capture variations in higher-order moments. A novelty of this chapter lies in adopting a set of nonlinear instruments that is to cope with this issue. They are very simple moment transformations of the characteristic-related instruments, thereby easy to obtain in practice. As expected, our simulations demonstrate that for a comparable amount of the bias corrected, applying the nonlinear instruments does entail an inclusion of fewer higher-order moments in estimation. A smaller simulated MSE that reveals the improvement over our previous estimation results can thus be achieved.\ 3. Precautionary Saving and Consumption with Borrowing Constraint This last chapter offers a theoretical underpinning for the importance of the higher-order moments in a simple environment where economic agents have a quadratic-utility preference. The resulting Euler equation gives rise to a linear policy function in essence, or a random-walk consumption rule. The twist in our theory comes from a presence of borrowing constraint facing consumers. The analysis shows that the presence of the constraint induces precautionary motives for saving as responses from consumers to income uncertainties, even there has been no such motives inherent in consumers' preference. The corresponding value function now displays a convexity property that is virtually only associated with more general preferences than a quadratic utility. The analytical framework allows us to be able to characterize saving behaviors that are of precautionary motives, and their responses to changes in different moments of income process. As empirical implications, our analysis shed new light on the causes of excess sensitivity, the consequences of sample splitting between the rich and the poor, as well as the relevance of the higher-order moments to consumption dynamics, specifically skewness and kurtosis.

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