本研究探討長期投資人之最適資產配置問題，並著重於通貨膨脹風險之分析。第一部份討論確定提撥退休金制度下，機構投資人或高所得自然人如何擬定投資策略規避通貨膨脹風險，達到極大化期末財富效用期望值。此研究擴展Battocchio與Menoncin (2004)所建構資產模型，不僅探討市場風險，亦考量通貨膨脹不確定性與基金費用誘因、下方風險保護兩機制，研究對資產配置行為之影響，並依動態規劃方法求得投資策略公式解。第二部份則強調下方風險之重要性，檢視在最低保證收益下，長期投資人跨期資產配置之財富管理議題，並回顧Deelstra et al.(2003)之模型架構，依平賭方法求得投資策略公式解，研究結果顯示基金投資策略可表示為最適CRRA(γ,T)型態共同基金與最低收益避險之組合。另一方面，如何估計通貨膨脹風險亦為本文強調之重點。Campbell和Viceira (2001)首次納入通貨膨脹風險並探討跨期投資議題，結論市場缺乏通貨膨脹連動投資標的時，投資人將減碼長期債持有比例。Brennan和Xia (2002)假設通貨膨脹率服從Ornstein-Uhlenbeck過程，結論投資人之避險需求隨持有債券到期日與投資期限改變。但以上結論未將通貨膨脹學習機制納入模型，因此，在第三部份提出依學習機制修正之投資策略可顯著增加財富效用，並分析在不同參數設定下，學習機制對於期末財富效用之影響。 / In this study, we study three essays of asset allocation problem for long term investors, which means that in this discourse we emphasis the importance of inflation risk. In the first topic, we derive the dynamic optimal investment strategy of the defined contribution pension schemes which include two mechanisms of partial floor protection and incentive fees and their benchmarks. We find investors should hold high proportion of stock index fund to hedge the inflation risk; moreover, the ratio of incentive fees to the setting of benchmark will change the optimal investment trend of underlying assets. In the second topic, we introduce the optimal investment portfolio with minimum guarantees and show that the fund manager should adjust the optimal weights of underlying assets with the ratio of the guarantee fund's value to the value of fund. Finally, this work focuses on how to precisely predict the dynamics of inflation rate. We apply learning method to adjust the prediction of inflation process and we use numerical analysis to study the effect of learning mechanism under different parameter setting.

隨著美國次級房貸衝擊世界經濟的影響不斷擴大，各國政府對於全球景氣的提振，莫不推出各種拯救方案。同時，為使相關拯救政策的效果得以發揮，各國央行莫不競相調降基準利率，以減輕投資者與消費者的資金成本壓力，企求藉此增加企業的投資意願與民眾的消費慾望，進而促使經濟景氣得以反轉為多。然而，欲使一國貨幣政策發揮其效果，除了社會大眾對於通貨膨脹預期的心理是否可以獲得消弭外，更重要的是央行貨幣政策傳遞管道是否暢通，是否對於整體經濟情勢仍具有相當的控制能力。而這些條件是否可以達成，而使央行貨幣政策確實可以發揮功效，其最主要的關鍵點除了與其所採行的貨幣運作機制有密切關係外，央行的獨立性、權責性與透明性的良窳更是具有決定性的因素。 然而，就臺灣而言，我國中央銀行法自一九七九年重新訂定後，僅於民國一九九七年大幅修訂，且於二ＯＯ二年時小幅修訂部分條文。但面對目前金融情勢變化快速與國內政治局勢的動盪，條文中對於有關央行獨立性地位的確認與央行權責性暨透明性的提昇等等現代化中央銀行所需具備的前提要件，卻似乎規範不甚明確。加以面對因金融自由化所造成市場中貨幣定義的模糊，以及貨幣目標制下政策效率不彰的困境，對於目前仍採行貨幣目標制做為政策執行架構的我國央行而言，其是否擁有其他可行的因應方式與選擇？是否需要追隨世界金融先進國家的腳步，更改目前的貨幣運作機制？是否通貨膨脹目標制對我國央行而言，具有執行上的絕對優勢？我國央行是否已經具備執行此項貨幣機制的相關必要條件？這些議題在國內相關文獻的探討中尚屬進一步探索的領域。故本文希冀透過對於我國央行獨立性、權責性、透明性以及其他主客觀經濟情勢的重新檢視，提出面臨的問題點以及可行的解決方案，以增進我國貨幣政策執行的有效性。 / With the more impacts on the economics in the world from the shocks of subprime-mortgage in America, many policies were proposed from every government to make the economic return the normal situation. For strengthening the effects of these policies, many central banks announced to cut the key interest rates. Because they wish could lighten the enterprises’ and consumers ‘costs of the capital by these policies, and then make them increasing the desires of the investments and consumptions to let the whole economic situations back to good ones. However, whether the monetary policies really have the effects or not, it depends on many elements, including if the central bank eliminates the expectations of inflation of the public or not, the monetary transmission channels could work successfully or not, the central bank could control the key economic variables or not and others seriously. Nevertheless, the monetary policy mechanism of this country, the level of independence, accountability and transparency of the central bank are the key factors that could influence these conditions work valid or not. In Taiwan, The Central Bank of China Act was amended in 1979. In 1997, this law was modify widely and revised few articles in 2002. However, these articles were not being considered how to make affirm the independence position of the central bank, and how to improve the accountability and transparency of the central bank to make the CBC meet the conditions of the modern central bank. Beside this, in the difficult status of the blurred definition of the money and of weakly effectiveness of the monetary policy in the monetary targeting framework, whether the CBC which still adopts the monetary targeting to be the main monetary policy mechanism has any choices to break these problems or not ? Whether the CBC needs to follow the advanced countries to alter the monetary policy mechanism to the inflation targeting framework? Whether the CBC could get more benefits to adopt the inflation targeting? And whether the CBC could meet all the preconditions of the inflation targeting? These issues are so important but not to be discussed in domestic academic literatures. Therefore we want to review the level of the independence, accountability and transparency of the CBC and other economic conditions to see the problems of the monetary policy mechanism in Taiwan. And then, we will provide the feasible suggestions to these problems to improve our monetary policy effectiveness.

本文基本上承襲 Weil(1991)的分析架構，以貨幣在效用函數模型(money-in-the utility model)來分析通貨替代的問題，也就是研究在一個整合的經濟體中，兩種通貨可替代時，高成長率通貨與低成長率通貨彼此競爭流通市場所可能產生的結果。本文改採不連續時間的模型，並引用 Fukuda(1997)的分析，分別以期末實質貨幣餘額及期初實質貨幣餘額放入效用函數中，比較其結果的差異。我們發現期初貨幣模型之各組恆定均衡解(steady state equilibrium)均可能出現多重收斂路徑，如此一來，Weil(1991)所提出的「劣幣逐良幣」現象未必會成為通貨競爭的必然結果。 除此之外，我們以兩個特定的效用函數為例(log-linear, CRRA)，以求進一步了解 Weil(1991)結論的模型適應性(robustness)。我們發現在線性對數效用函數的推導下，期初、期末貨幣模型所得到的結果並沒有明顯的分別，但 CRRA 模型的結果則顯示，期初貨幣模型的結論不同於 Weil(1991)。 / The study issues and analytical framework of this thesis follow Weil(1991). We apply the money-in-the-utility model (M.I.U. model) to analyze several issues in currency substitution. We want to investigate the monetary equilibria and their stability when there are two substitutable currencies in an integrated economy. Specifically, we want to know whether the faster growing currency will drive the slower growing ones out of the market, or vise versa. Unlike Weil(1991), we base our model on a discrete-time basis Following the study of Fukuda(1997), we use two different approaches to put the real money balances in the utility function. One is "end-of-the-period" M.I.U. model, and the other is "beginning-of-the-period" M.I.U. model. We make the comparison of the result of the two alternative approaches. Furthermore, we contrast our outcomes against those of Weil(1991). Besides the analysis based upon the general utility form, we also provide analysis of two specific utility functions. Except for the log-linear utility function, we find that there are significant differences between the two alternatives timing framework. The "beginning-of-the-period" M.I.U. model shows that "Gresham's Law" would not necessarily be the inevitable outcome of the economy with two perfectly substitutable currencies. Thus, it limits the validity of the conclusion of Weil(1991).

本篇論文擴充Ang et al. (2007)之基本架構,分別建構台灣各式月資料與季資料的物價指數預測模型,並進行預測以及實證分析。我們用以衡量通貨膨脹率的指標為 CPI 年增率與核心CPI 年增率。我們比較貨幣模型、成本加成模型、6 種不同設定的菲力浦曲線模型、3 種期限結構模型、隨機漫步模型、 AO 模型、ARIMA 模型、VAR 模型、主計處(DGBAS)、中經院(CIER) 及台經院(TIER) 之預測。藉由此研究,我們可以完整評估出文獻上常用之各式月資料及季資料預測模型的優劣。 我們實證結果顯示,在月資料預測模型樣本外預測績效表現方面, ARIMA 模 型對 2 種通貨膨脹率指標的樣本外預測能力表現最好。至於季資料預測模型樣本外預測績效表現, ARIMA 模型對未來核心 CPI 年增率的樣本外預測能力表現最好; 然而,對於 CPI 年增率為預測目標的預測模型則不存在最佳的模型。此外,實證分析中我們也發現本研究所建構的模型預測表現仍遜於主計處的預測,但部份模型的樣本外預測能力表現則比中經院與台經院的預測為佳。 / This paper compares the forecasting performance of inflation in Taiwan. We conduct various inflation forecasting methods (models) for two inflation measures(CPI growth rate and core-CPI growth rate) by using monthly and quarterly data. Besides the models of Ang et al. (2007), we also consider some macroeconomic models for comparison. We compare some Monetary models, Mark-up models, six variants of Phillips curve models, three variants of term structure models, a Random walk model, an AO model, an ARIMA model, and a VAR model. We also compare the forecast ability of these model with three different survey forecasts (the DGBAS, CIER, and TIER surveys). We summarized our findings as follows. The best monthly forecasting model for both inflation measures is ARIMA model. For quarterly core-CPI inflation, ARIMA model is also the best model; however, when comparing the quarterly forecasts for CPI inflation, there does not exist the best one. Besides, we also found that the DGBAS survey outperforms all of our forecasting methods/models, but some of our forecasting models are better than the CIER and TIER surveys in terms of MAE.

本文建構代理人基之社會網路新凱因動態隨機一般均衡模型(Social Network-Based DSGE model)，並分別使用權衡性門檻型泰勒法則與一般線型泰勒法則作為代理人基之社會網路新凱因斯動態一般均衡模型中的貨幣政策方程式，模擬產出缺口、通貨膨脹、利率等總體經濟變數資料，接著利用模擬資料，探討不同網路結構對產出缺口、通貨膨脹等總體經濟變數的影響，同時比較權衡性貨幣政策與法則性貨幣政策穩定經濟的有效性。 　　透過產出缺口與通貨膨脹的波動性分析，本研究發現某些特定社會網路結構的影響力大於貨幣政策的影響力，決定了經濟變數的波動程度。在完全連結網路(Fully)的結構下，通貨膨脹與產出缺口的波動度明顯低於其他結構，而無標度網路(Scalefree)的結構會使產出與通膨的波動程度最大。經過驗證，本研究發現群聚度大、平均路徑短的網路結構內節點之間資訊流通速度較快，對穩定經濟有正面助益；相反的，由於無標度網路強大的中心性，使該網路內指標性節點對其餘節點具有龐大影響力，增加節點內決策的不確定性，連帶造成經濟的大幅波動。另外，在相同的網路結構下比較權衡與法則貨幣政策，研究結果指出權衡性政策會造成較大的產出缺口波動，但對抑制通貨膨脹波動的效果較佳；相對的，法則性政策對產出缺口的穩定效果較好，但卻無法兼顧通貨膨脹的波動性。 / We construct an agent-based New Keynesian DSGE model (Dynamic Stochastic General Equilibrium) with different social network structures to investigate the effects of the rule and discretion monetary policy. According to our simulation results, we find the economic stability depends on the specific social network structure rather than the monetary policy basis like rule and discretion. Generally speaking, the more average path length (the less average clustering coefficient) the network structure is, the more economic fluctuation would be. Also, the results show that scalefree network will lead the most dramatic economic fluctuations. These results are ascribed to scale -free’s high centrality. However, if the social network structure is too complicate to control, the central banker can only manipulate the monetary policy to stabilize the economy. With different policy basis, we find the rule monetary policy will lead less output gap volatility.