In this paper we focus on the problem of estimating a bounded density using a finite combination of densities from a given class. We consider the Maximum Likelihood Procedure (MLE) and the greedy procedure described by Li and Barron. Approximation and estimation bounds are given for the above methods. We extend and improve upon the estimation results of Li and Barron, and in particular prove an $O(\\frac{1}{\\sqrt{n}})$ bound on the estimation error which does not depend on the number of densities in the estimated combination.

In this paper we focus on the problem of estimating a boundeddensity using a finite combination of densities from a givenclass. We consider the Maximum Likelihood Procedure (MLE) and the greedy procedure described by Li and Barron. Approximation and estimation bounds are given for the above methods. We extend and improve upon the estimation results of Li and Barron, and in particular prove an $O(\frac{1}{\sqrt{n}})$ bound on the estimation error which does not depend on the number of densities in the estimated combination.

Syftet med studien är att undersöka hur måltiden kan ses som en demokratisk arena genom att ta del av barns och pedagogers uppfattningar. De två frågeställningar studien utgår ifrån är: Hur uppfattar barn möjligheten till eget inflytande under måltiden? Hur kan pedagoger samtala om demokrati i måltidssituationen?   Kleins fem samspelskriterier används som teoretiskt analys verktyg. I studien har både barn och vuxna intervjuats. Resultatet visar att samspelskriterierna kan underlätta det demokratiska arbetet i förskolans måltid.

Copula functions represent a methodology which can describe the dependence structure of multi-dimension random variable, and has recently become the most significant new tool to handle risk factors in finance such as Value-at Risk( VaR) which was probably the most widely used risk measure in financial institutions. In this paper, Copula and the forecast function of Garch model are well combined, and a new method Conditional-Copula-Garch is built for measure the dependence of financial data and compute the VaR of portfolios. Copula-Garch models allow for very flexible joint distribution by splitting the marginal behaviors form the dependence relation unlike the traditional approaches for the estimation VaR, such as variance-covariance, and the Monte Carlo approaches whereas demand the joint distribution to be known. This work presents an application of the Copula-Garch model in the estimation of VaR of a portfolio composed by NASDAQ and TAIEX (Taiwan stock exchanged capitalization weighted index) stock indices.

Syftet med studien är att bidra med kunskap om hur pedagoger beskriver att de bemöter känslor i förskolan. Följande frågeställning fokuseras i studien: Hur beskriver pedagoger att de förhåller sig till och bemöter känslor i förskolan? Studien är genomförd med fokusgruppsintervju som metod där tio yrkesverksamma pedagoger i förskolan deltagit i tre olika fokusgrupper. Datainsamlingen har analyserats utifrån Kleins fem samspelskriterier: avsikt och ömsesidighet, innebörd, utvidgade erfarenheter, duglighetskänsla och inverkan på tillvägagångsätt eller reglering av beteende. Resultatet visar att arbetet med barns känslor är beroende av flera faktorer så som social kompetens och emotionell mognad. Bemötandet av känslorna ses som avgörande i det sociala samspelet på förskolan. Mognad och verbal utveckling anses som förutsättningar för barns reglering av sina känslor. Resultatet visar även att det är en balansgång mellan att vara professionell och privat i sitt känslospel i rollen som pedagog i förskolan.

<p>Research interests in the studies of complex systems have been booming in many disciplines for the last decade. As the nature of geographic environment is a complex system, researches in this field are anticipated. In particular, the urban street networks in the Geographic Information System (GIS) as complex networks are brought forth for the thesis study. Meanwhile, identifying the scale-free property, which is represented as the power law distribution from a mathematical perspective, is a hot topic in the studies of complex systems. Many previous studies estimated the power law distributions with graphic method, which used linear regression method to identify the exponent value and estimate the quality that the power law fits to the empirical data. However, such strategy is considered to cause inaccurate results and lead to biased judgments. Whereas, the Maximum Likelihood Estimation (MLE) and the Goodness of fit test based on Kolmogorov-Smironv (KS) statistics will provide more solid and trustable results for the estimations. Therefore, this thesis addresses these updated methods exploring the topological patterns of urban street networks from an analytical perspective, which is estimating the power law distributions for the connectivity degree and length of the urban streets. Simultaneously, this thesis explores the street networks from a visual perspective as well. The visual perspective adopts the large network visualization tool (LaNet-vi), which is developed based on the k-core decomposition algorithm, to analyze the cores of the urban street networks. By retrieving the spatial information of the networks from GIS, it actually enables us to see how the urban street networks decomposed topologically and spatially. In particular, the 40 US urban street networks are reformed as natural street networks by using three "natural street" models.</p><p>The results from analytical perspective show that the 80/20 principle still exists for both the street connectivity degree and length qualitatively, which means around 20% natural streets in each network have a connectivity degree or length value above the average level, while the 80% ones are below the average. Moreover, the quantitative analysis revealed the fact that most of the distributions from the street connectivity degree or length of the 40 natural street networks follow a power law distribution with an exponential cut-off. Some of the rest cases are verified to have power law distributions and some extreme cases are still unclear for identifying which distribution form to fit. The comparisons are made to the power law statement from previous study which used the linear regression method. Moreover, the visual perspective not only provides us the chance to see the inner structures about the hierarchies and cores of the natural street networks topologically and spatially, but also serves as a reflection for the analytical perspective. Such relationships are discussed and the possibility of combining these two aspects are pointed out. In addition, the future work is also proposed for making better studies in this field.</p>

Jorda (2005) proposed the new method to estimate impulse response functions by local projection. The new method, local projection, can avoid the misspecification problem. That is, local projections are robust to misspecification of the data generating process (DGP). Wu, Lee, and Wang (2008) extended the Jorda¡¦s local projection from stationary time series I(0) to non-stationary time series I(1). It makes the local projection be a more generally applicative method for the Macroeconomic. In the article, I relax the cointegration vector which assumed to be known in the Wu, Lee, and Wang (2008) and Lee(2010). From the inference of Johansen (1995) I can get the property of super-consistent between £] and ˆ £] in the cointegration vector. I use the above condition and OLS to estimate impulse response functions, and in the asymptotic theorem, the cointegration vectors which assumed to be known or estimated by Johansen MLE are both get the consistent coefficients of impulse responses.

Research interests in the studies of complex systems have been booming in many disciplines for the last decade. As the nature of geographic environment is a complex system, researches in this field are anticipated. In particular, the urban street networks in the Geographic Information System (GIS) as complex networks are brought forth for the thesis study. Meanwhile, identifying the scale-free property, which is represented as the power law distribution from a mathematical perspective, is a hot topic in the studies of complex systems. Many previous studies estimated the power law distributions with graphic method, which used linear regression method to identify the exponent value and estimate the quality that the power law fits to the empirical data. However, such strategy is considered to cause inaccurate results and lead to biased judgments. Whereas, the Maximum Likelihood Estimation (MLE) and the Goodness of fit test based on Kolmogorov-Smironv (KS) statistics will provide more solid and trustable results for the estimations. Therefore, this thesis addresses these updated methods exploring the topological patterns of urban street networks from an analytical perspective, which is estimating the power law distributions for the connectivity degree and length of the urban streets. Simultaneously, this thesis explores the street networks from a visual perspective as well. The visual perspective adopts the large network visualization tool (LaNet-vi), which is developed based on the k-core decomposition algorithm, to analyze the cores of the urban street networks. By retrieving the spatial information of the networks from GIS, it actually enables us to see how the urban street networks decomposed topologically and spatially. In particular, the 40 US urban street networks are reformed as natural street networks by using three "natural street" models. The results from analytical perspective show that the 80/20 principle still exists for both the street connectivity degree and length qualitatively, which means around 20% natural streets in each network have a connectivity degree or length value above the average level, while the 80% ones are below the average. Moreover, the quantitative analysis revealed the fact that most of the distributions from the street connectivity degree or length of the 40 natural street networks follow a power law distribution with an exponential cut-off. Some of the rest cases are verified to have power law distributions and some extreme cases are still unclear for identifying which distribution form to fit. The comparisons are made to the power law statement from previous study which used the linear regression method. Moreover, the visual perspective not only provides us the chance to see the inner structures about the hierarchies and cores of the natural street networks topologically and spatially, but also serves as a reflection for the analytical perspective. Such relationships are discussed and the possibility of combining these two aspects are pointed out. In addition, the future work is also proposed for making better studies in this field.

Some youth in London speak a non-standard variety of English whose lexical items are difficult for non-speakers to understand. This study collected naturally produced speech samples from students of various ethnicities and class backgrounds who spoke this dialect. It also polled students about their identity, as well as about their use of particular slang words. The recordings were glossed to determine the kind of slang used, as well which populations were more or less likely to use slang. The surveys were analyzed to determine relevant background characteristics of those who used slang versus those who did not. This study concludes that one’s geographic background, as well as one’s class and peer group, impact the variety of English spoken. The idea of language as a method of counter culture is advanced, claiming that speakers are using this dialect as a way to signify resistance against the highly rigid class systems of the U.K.

Let (X, Y) be bivariate normal random vectors which represent the responses as a result of Treatment 1 and Treatment 2. The statistical inference about the bivariate normal distribution parameters involving missing data with both treatment samples is considered. Assuming the correlation coefficient ρ of the bivariate population is known, the MLE of population means and variance (ξ, η, and σ2) are obtained. Inferences about these parameters are presented. Procedures of constructing confidence interval for the difference of population means ξ – η and testing hypothesis about ξ – η are established. The performances of the new estimators and testing procedure are compared numerically with the method proposed in Looney and Jones (2003) on the basis of extensive Monte Carlo simulation. Simulation studies indicate that the testing power of the method proposed in this thesis study is higher.