This study tests for the market efficiency of the Nairobi Securities Exchange (NSE) after the year 2000 to determine the effect of technological advancements on market efficiency. Data that is used is the NSE 20 share index over the period 2001 to 2015; and the NSE All Share Index (NSE ASI) from its initiation during 2008 to 2015. We cannot accept the Efficient Market Hypothesis (EMH) for the NSE using the serial correlation test, the unit root tests and the runs test. However, we can accept the EMH for the more robust variance ratio test. Overall, the results of the market efficiency are mixed. The most significant finding is that the efficiency of the NSE has increased since the year 2000 which suggests that advancements in technology have contributed to the increase in the market efficiency of the NSE. / Business Management / M. Com. (Business Management)

This research has studied the relationship between insider trading activity and its effect on the level of informational efficiency. The authors have used insider data from Finansinspektionen and data regarding stock prices, market capitalization and GDP from Thomson Reuters Datastream. The sample includes 193 companies on the Swedish stock exchange for a period of 10 years. A Variance Ratio test employed on moving sub-sample windows was used to establish the level of time-varying informational efficiency, which subsequently was used in an OLS-regression as a dependent variable. The result of the regression implies a negative effect on firm price information efficiency by insider purchasing, while selling has a positive effect. This can be concluded using a confidence level of 99%. The results are interesting since they imply an asymmetrical effect of insider trading on informational efficiency, while current insider legislation treats buying and selling by insiders equal. Thus, the results are of interest in future adjustments of laws regulating insider trading.

More retail and service firms are using mystery shoppers in Taiwan to monitor their frontline operations and to assess their customer service, since the concern over whether their customers are truly satisfied is increasing. However, virtually nothing is known about whether the quality of the data collected by professional mystery shoppers is different or more reliable than that of shoppers disguised by general customers. Here we use a traditional statistics approach to assess the quality of data collected from both professional mystery shoppers and general customers. Feedback questionnaires from general customers and the potential use of mystery shoppers are made as a means of evaluating the service quality of cram schools in Taiwan. The purpose of this thesis is to show that the reliability of mystery shopping data made from professional mystery shoppers is higher than that of data made from general customers. With this question in mind, we conducted a two-step empirical research, as the amount of samples needed was insufficient. First, a primary study to examine the equality of population among branches was carried out in order to pool data from different branches. Then, the relative reliability of the surveys of mystery shoppers to general customers was examined by pooling data of the branches together. The findings provide evidence to suggest that reliable information could be obtained by pooling both shopper reports together. This empirical result also implied that well-trained mystery shoppers can make more objective observations and more effective assessments than general customers.

This thesis conducts a comprehensive examination on the random walk behavior of 29 foreign exchange rates over the period of floating exchange regime, using variance-ratio tests. The cross-country and time-series test show that random walk model cannot be rejected on majority, and the random walk behavior is quite volatile across the whole floating exchange regime period. It then goes further to explore possible factors that can explain the probability of rejection/ non-rejections on random walk model using linear as well as nonlinear probability models, and find that the factors such as capital openness and investment-to-trade ratio significantly increases the chance of its exchange rate exhibiting random walk behavior.

The stock market has been objective of many researches that seek to identify the presence of some previsibility degree in the return series. Inside of this context grew the Market Efficiency Theory divided in three forms: weak efficiency, semi-strong and strong. The random walk hypothesis was created to test, empirically, the Market Efficiency in the weak-form. Acceptance or rejection brings implications as the possibility of its to get to foresee, somehow, based in past returns, the future returns, removing advantage of that to gain extraordinary incomes. To test the random walk, specialists in this subject they created, along the years, methods and, among these, they stand out the variance ratio tests that, initially they were applied in developed markets and, nowadays, it has also been used at emerging markets. For the development of the present research, with the intention of testing the random walk hypothesis in an emerging market (Brazil) and in a developed market (United States), were implemented the following variance ratio tests: simple, multiple, based in the ranks and signs. The returns of IBOVESPA were used, as proxy of the Brazilian stock market, and of S&P 500, to the North American market, collected daily and weekly in the period of January 03, 2000 to April 25, 2008. The results demonstrated an acceptance of the random walk hypothesis in most of the made tests appearing for a weak form of market efficiency. / O mercado de ações tem sido alvo de muitas pesquisas que visam identificar a presença de algum grau de previsibilidade nas séries de retornos. Dentro deste contexto desenvolveu-se a Teoria de Eficiência de Mercado dividida em três formas: eficiência fraca, semiforte e forte. A hipótese do caminho aleatório foi criada para testar, empiricamente, a Eficiência de Mercado na forma fraca. Sua aceitação ou rejeição traz implicâncias quanto a possibilidade de se conseguir prever, de alguma maneira, com base em retornos passados, os retornos futuros, tirando proveito disso para auferir rendimentos extraordinários. A fim de testar a hipótese do caminho aleatório estudiosos do assunto criaram, ao longo dos anos, métodos e, dentre estes, destacam-se os testes de quociente de variâncias que, inicialmente foram aplicados em mercados desenvolvidos e, atualmente, também tem sido utilizados em mercados emergentes. Para o desenvolvimento da presente pesquisa, com o intuito de testar a hipótese do caminho aleatório em um mercado emergente (Brasil) e em um mercado desenvolvido (Estados Unidos), foram aplicados os seguintes testes de quociente de variâncias: simples, múltiplas, com base nos postos e com base nos sinais. Foram utilizados os retornos do IBOVESPA, como proxy do mercado acionário brasileiro, e do S&P 500, para o mercado norte-americano, coletados diariamente e semanalmente no período de 03 de janeiro de 2000 a 25 de abril de 2008. Os resultados demonstraram uma aceitação da hipótese do caminho aleatório na maioria dos testes efetuados apontando para uma forma fraca de eficiência de mercado.

本論文是二篇探討與股票價格平均數復歸現象有關的實證文章。在第一篇文章中，我們將探討由於廠商特質所產生資金供需雙方訊息的非對稱，而引發的流動性限制對廠商股票價格行為的潛在影響；在第二篇文章中，我們研究的課題是在漲跌幅限制下，交易量與股票報酬自我相關的關係。 第一篇文章主要在探討由於廠商特質所產生資金供需雙方訊息的非對稱，而引發的流動性限制對廠商股票價格行為的影響。我們利用五個廠商特質－所有權結構、集團企業成員、上市時間、公司規模與現金股利的發放，定義面臨流動性限制的廠商，並使用變異數比率衡量股票價格平均數復歸的現象，由於小樣本的問題，我們將利用拔靴法檢定假說：廠商的流動性限制會強化其股票價格平均數復歸的行為。我們的實證結果並不一致，所有權結構、公司規模和集團企業成員的分組實證結果支持我們的假說，流動性限制會強化平均數復歸的行為；而上市時間與現金股利發放的分組實證結果並不支持我們的假說。 在第二篇文章中，我們使用與Campbell et. al. (1993)相同的實證模型，討論在漲跌幅限制下，交易量與股票日報酬自我相關的關係。由於漲跌幅限制的存在，當股票價格觸及漲跌幅上下限時，即停止交易，而使得真正的股票價格無法觀察到，因而未實現之需求或供給將會傳遞至下一個交易日，將使傳統OLS或其衍生方法的估計產生偏誤，而使用Chou和Chib (1995)與Chou (1995)所提的Gibbs抽樣法則可以成功地克服這些困難。所以，本文將應用Chou和Chib (1995)與Chou (1995)的Gibbs抽樣法來衡量台灣股票市場交易量對股票日報酬自我相關係數的影響，以避免漲跌幅限制的影響。本文採用台灣證交所編製的綜合股價指數所採樣的二十四家公司為樣本，利用日資料進行實證分析，實證結果支持「交易量效果」的存在。且在實證過程中，發現台灣股票市場股票日報酬的正自我相關有可能是漲跌幅限制的存在而造成的。

This thesis presents a collection of papers that has been published, accepted or submitted for publication. They assess price, volatility and market relationships in the five regional electricity markets in the Australian National Electricity Market (NEM): namely, New South Wales (NSW), Queensland (QLD), South Australia (SA), the Snowy Mountains Hydroelectric Scheme (SNO) and Victoria (VIC). The transmission networks that link regional systems via interconnectors across the eastern states have played an important role in the connection of the regional markets into an efficient national electricity market. During peak periods, the interconnectors become congested and the NEM separates into its regions, promoting price differences across the market and exacerbating reliability problems in regional utilities. This thesis is motivated in part by the fact that assessment of these prices and volatility within and between regional markets allows for better forecasts by electricity producers, transmitters and retailers and the efficient distribution of energy on a national level. The first two papers explore whether the lagged price and volatility information flows of the connected spot electricity markets can be used to forecast the pricing behaviour of individual markets. A multivariate generalised autoregressive conditional heteroskedasticity (MGARCH) model is used to identify the source and magnitude of price and volatility spillovers within (intra-relationship) and across (inter-relationship) the various spot markets. The results show evidence of the fact that prices in one market can be explained by their own price lagged one-period and are independent of lagged spot prices of any other markets when daily data is employed. This implies that the regional spot electricity markets are not fully integrated. However, there is also evidence of a large number of significant ownvolatility and cross-volatility spillovers in all five markets indicating that shocks in some markets will affect price volatility in others. Similar conclusions are obtained when the daily data are disaggregated into peak and off-peak periods, suggesting that the spot electricity markets are still rather isolated. These results inspired the research underlying the third paper of the thesis on modelling the dynamics of spot electricity prices in each regional market. A family of generalised autoregressive conditional heteroskedasticity (GARCH), RiskMetrics, normal Asymmetric Power ARCH (APARCH), Student APARCH and skewed Student APARCH is used to model the time-varying variance in prices with the inclusion of news arrival as proxied by the contemporaneous volume of demand, time-of-day, day-of-week and month-of-year effects as exogenous explanatory variables. The important contribution in this paper lies in the use of two latter methodologies, namely, the Student APARCH and skewed Student APARCH which take account of the skewness and fat tailed characteristics of the electricity spot price series. The results indicate significant innovation spillovers (ARCH effects) and volatility spillovers (GARCH effects) in the conditional standard deviation equation, even with market and calendar effects included. Intraday prices also exhibit significant asymmetric responses of volatility to the flow of information (that is, positive shocks or good news are associated with higher volatility than negative shocks or bad news). The fourth research paper attempts to capture salient feature of price hikes or spikes in wholesale electricity markets. The results show that electricity prices exhibit stronger mean-reversion after a price spike than the mean-reversion in the normal period, suggesting the electricity price quickly returns from some extreme position (such as a price spike) to equilibrium; this is, extreme price spikes are shortlived. Mean-reversion can be measured in a separate regime from the normal regime using Markov probability transition to identify the different regimes. The fifth and final paper investigates whether interstate/regional trade has enhanced the efficiency of each spot electricity market. Multiple variance ratio tests are used to determine if Australian spot electricity markets follow a random walk; that is, if they are informationally efficient. The results indicate that despite the presence of a national market only the Victorian market during the off-peak period is informationally (or market) efficient and follows a random walk. This thesis makes a significant contribution in estimating the volatility and the efficiency of the wholesale electricity prices by employing four advanced time series techniques that have not been previously explored in the Australian context. An understanding of the modelling and forecastability of electricity spot price volatility across and within the Australian spot markets is vital for generators, distributors and market regulators. Such an understanding influences the pricing of derivative contracts traded on the electricity markets and enables market participants to better manage their financial risks.

本研究目的在於探討Put-Call Parity（PCP）所隱含的買權、賣權與標的資產間的價格變動關係。藉由探討PCP偏差程度的動態行為，推論若PCP的偏差為隨機漫步過程，則無法達到長期穩定，隱含PCP的廣義關係無法成立；反之，若PCP的偏差具有回歸平均特性，表示長期會達到穩定狀態，則PCP的廣義關係成立。 在研究方法上本文以變異數比率法檢定指數選擇權的PCP偏差是否為隨機漫步過程，採用隱含利率和實際無風險利率的差代表PCP的偏差程度，利用馬可夫轉換模型描繪PCP偏差的動態行為，並使用Gibbs Sampling演算法說明參數的不確定性。 本文以S&P500和DAX為研究標的，並探討股利不確定性是否影響PCP廣義關係，得到下列結論： 1、 對於S&P 500指數選擇權而言，不論是以日資料或週資料估計VR，S&P 500的PCP偏差都無法提供回歸平均的證據，隱含S&P 500的PCP廣義關係無法成立。 2、 對於DAX指數選擇權而言，檢定日資料的結果發現，DAX之PCP偏差在長期時（40~50日）有明顯的回歸平均的證據；而在檢定週資料時，使用原始資料法在90%信心水準下，不論取任何lag都可拒絕虛無假設，使用標準化資料則無法提供明顯的回歸平均證據。 3、 比較S&P 500和DAX，檢定日資料與週資料的結果都發現，DAX的p-value都比S&P 500小，並且S&P 500的PCP偏差都無法提供回歸平均的證據，而DAX有明顯回歸平均現象，隱含在消除股利的不確定性後，指數選擇權PCP的廣義關係式成立之證據較強烈。

This study tests for the market efficiency of the Nairobi Securities Exchange (NSE) after the year 2000 to determine the effect of technological advancements on market efficiency. Data that is used is the NSE 20 share index over the period 2001 to 2015; and the NSE All Share Index (NSE ASI) from its initiation during 2008 to 2015. We cannot accept the Efficient Market Hypothesis (EMH) for the NSE using the serial correlation test, the unit root tests and the runs test. However, we can accept the EMH for the more robust variance ratio test. Overall, the results of the market efficiency are mixed. The most significant finding is that the efficiency of the NSE has increased since the year 2000 which suggests that advancements in technology have contributed to the increase in the market efficiency of the NSE. / Business Management / M. Com. (Business Management)

Le premier chapitre examine les caractéristiques statistiques à long terme des rendements financiers en France et aux USA. Les propriétés des différents actifs font apparaître qu’à long terme les actions procurent un risque sensiblement moins élevé. En outre, les propriétés de retour à la moyenne des actions justifient qu’elles soient utilisées dans une stratégie de cycle de vie comme « option par défaut » de plans d’épargne retraite. Le chapitre deux fournit une explication au débat sur l'hypothèse d’efficience des marchés. La cause du débat est souvent attribuée à la petite taille des échantillons et à la faible puissance des tests statistiques dédiés. Afin de contourner ce problème, nous utilisons l'approche développée par Campbell et Viceira (2005) qui utilisent une méthode VAR pour mettre en évidence l’existence de retour vers la moyenne dans le cours des actifs risqués.Le troisième chapitre évalue la vitesse de convergence des cours des actions. Un moyen classique pour caractériser la vitesse de retour vers la moyenne est la « demi-vie ». En comparant les indices boursiers de quatre pays développés (États-Unis, Royaume-Uni, France et Japon) sur la période 1950-2014, nous établissons une vitesse de convergence significative, avec une demi-vie entre 4,0 et 5,8 ans.Le dernier chapitre présente les résultats d'un modèle conçu pour étudier les interactions entre la démographie et les régimes de retraite. Afin d’étudier les risques inhérents à l’utilisation des revenus du capital pour financer les retraites, nous utilisons un « Trending OU process » au lieu d’un MBG classique pour modéliser les rendements. Pour un épargnant averse au risque le marché pourrait concurrencer les régimes par répartition. / Chapter one examines the long run statistical characteristics of financial returns in France and the USA for selected assets. This study clearly shows that the returns’ distributions diverge from the Gaussian strategy as regards longholding periods. Thereafter we analyze the consequences of the non-Gaussian nature of stock returns on default-option retirement plans.Chapter two provides a reasonable explanation to the strong debate on the Efficient Market Hypothesis. The cause of the debate is often attributed to small sample sizes in combination with statistical tests for mean reversion that lackpower. In order to bypass this problem, we use the approach developed by Campbell and Viceira (2005) who have settled a vectorial autoregressive methodology (VAR) to measure the mean reversion of asset returns.The third chapter evaluates the speed of convergence of stock prices. A convenient way to characterize the speed of mean reversion is the half-life. Comparing the stock indexes of four developed countries (US, UK, France and Japan) during the period 1950-2014, we establish significant mean reversion, with a half-life lying between 4,0 and 5,8 years.The final chapter provides some results from a model built in order to study the linked impacts of demography and economy on the French pension scheme. In order to reveal the risks that are contained in pension fund investment, we use a Trending Ornstein-Uhlenbeck process instead of the typical GBM for modeling stock returns. We find that funded scheme returns, net of management fees, are slightly lower thanthe PAYG internal rate of return.