TWO-STAGE QUANTILE REGRESSION WHEN THE FIRST STAGE IS BASED ON QUANTILE REGRESSION

We present the asymptotic properties of double-stage quantile regression estimators with random regressors, where the first stage is based on quantile regressions with the same quantile as in the second stage, which ensures robustness of the estimation procedure. We derive invariance properties with respect to the reformulation of the dependent variable. We propose a consistent estimator of the variance-covariance matrix of the new estimator. Finally, we investigate finite sample properties of this estimator by using Monte Carlo simulations.Two-stage estimation, Quantile regression, Endogeneity.

Choice f micro-mobility: Case studies of ta public bicycle sharing system in New Zealand

This study considers how to improve understanding of sustainable urban transport planning from the perspective of the Central Business District (CBD) redevelopment process for two cities, Hamilton and Christchurch in New Zealand (NZ). The most proportion of ‘Public Bicycle Share Schemes’ operate in densely populated cities as these are characterized by limited modal accessibility but high population density in the urban CBD. This situation is similar to NZ’s two medium-sized cities, in each of which the city’s population density is constantly increasing in the past years. In this study, Multinomial and Mixed Logistic regression models were used to determine the model specification, and subsequently, to test the mode choice cross-elasticities for promoting greater use of the bicycle sharing system in conjunction with public transport service. The data were gathered using stated preference surveys from 486 New Zealanders, and the modeling results indicate that the potential improvement in a modal shift towards micro-mobility, which can be enhanced by applying different policy options

Estimating Monetary Reaction Functions at Near Zero Interest Rates: An Example Using Japanese Data

The importance of truncated distributions for bias in estimation of regression coefficients has been well understood by econometricians, but the relevance of truncation when estimating policy reaction functions has not been fully appreciated. Due to the emergence of low interest rates and the proximity of a zero lower bound (ZLB) on interest rates, coefficient estimates can be biased upwards. This paper illustrates the importance of measuring and correcting estimates for this bias using Japan’s unique experience of prolonged low inflation/deflation. While we would expect the monetary policy reaction function in Japan to differ from other countries in the G4, we show the bias from truncation of the interest rate distribution is significant and needs to be taken into account.Monetary policy, Reaction functions, Zero lower bounds, Japan, Tobit.

TWO-STAGE HUBER ESTIMATION

In this paper we study how the Huber estimator can be adapted to the presence of endogeneity in a two stage equations setting similar to that of 2SLS. We propose an estimation procedure that is at the same time relatively (i) simple, (ii) robust and (iii) efficient. Moreover, we deal with the case of random regressors and asymmetric errors, two extensions rarely present in this literature. The preliminary scale correction is implemented with median absolute deviation estimator, which is consistent with our above criteria and is a very robust estimator of scale. The resulting estimator is termed as the Two-Stage Huber (2SH) estimator. We explicitly establish the conditions for consistency and asymptotic normality of the 2SH estimator and we derive the formula of the asymptotic covariance matrix. We conduct Monte Carlo simulations whose results indicate that the 2SH estimator has smaller standard errors than the Two-Stage Least Squares (2SLS) estimator and than the Two-Stage Least Absolute Deviations (2SLAD) estimator in many situations. On the whole, the 2SH estimator appears to be a simple and useful alternative to 2SLS and 2SLAD in cases of two-stage estimation to deal with endogeneity when there are concerns for both robustness and efficiency.Two-stage estimation, Huber estimation, robustness, endogeneity

Design of One-Coincidence Frequency Hopping Sequence Sets for FHMA Systems

Department of Electrical EngineeringIn the thesis, we discuss frequency hopping multiple access (FHMA) systems and construction of optimal frequency hopping sequence and applications. Moreover, FHMA is widely used in modern communication systems such as Bluetooth, ultrawideband (UWB), military, etc. For these systems, it is desirable to employ frequency-hopping sequences (FHSs) having low Hamming correlation in order to reduce the multiple-access interference. In general, optimal FHSs with respect to the Lempel-Greenberger bound do not always exist for all lengths and frequency set sizes. Therefore, it is an important problem to verify whether an optimal FHS with respect to the Lempel-Greenberger bound exists or not for a given length and a given frequency set size. I constructed FHS satisfying optimal with respect to the Lempel-Greenberger bound and Peng-Fan bound for efficiency of available frequency. Parameters of a new OC-FHS set are length p^2-p over Z_(p^2 ) by using a primitive element of Z_p. The new OC-FHS set with H_a (X)=0 and H_c (X)=1 can be applied to several recent applications using ISM band (e.g. IoT) based on BLE and Zigbee. In the construction and theorem, I used these mathematical back grounds in preliminaries (i.e., finite field, primitive element, primitive polynomial, frequency hopping sequence, multiple frequency shift keying, DS/CDMA) in order to prove mathematically. The outline of thesis is as follows. In preliminaries, we explain algorithm for minimal polynomial for sequence, linear complexities, Hamming correlation and bounds for FHSs and some applications are presented. In section ???, algorithm for complexity, correlation and bound for FHSs and some applications are presented. In section ???, using information in section ??? and ???, a new construction of OC-FHS is presented. In order to prove the optimality of FHSs, all cases of Hamming autocorrelation and Hamming cross-correlation are mathematically calculated. Moreover, in order to raise data rate or the number of users, a new method is presented. Using this method, sequences are divided into two times of length and satisfies Lempel-Greenberger bound and Peng-Fan bound.clos

Challenges in research and development for the Korean aircraft industry

노트 : Book Title: Emerging Threats, Force Structures, and the Role of Air Power in Korea Chapter 14 Title: Challenges in research and development for the Korean aircraft industr

Production of Hexanoic Acid from Long Chain Fatty Acid in Escherichia coli

Department of Biomedical EngineeringAll over the world, the efforts are under way to find the petroleum replacement resources in order to overcome fossil fuel depletion and to reduce greenhouse-gas emissions. In this respect, replacing petrochemicals with renewable alternatives is one of the principal challenges of our day. Hexanoic acid could be widely used as a precursor to biofuels and for the production of chain based chemicals such as adipic acid, hexane, amino-caproic acid and so on. In order to produce specific carbon chain fatty acid, Escherichia coli ??-oxidation pathway was engineered. First, fadE and fadR genes were deleted. And then, E. coli acyl-CoA dehydrogenase (FadE) was replaced with acyl-CoA oxidase 2 encoded by POX2 gene from Yarrowia lipolytica, which has substrate specificity towards medium to long chain fatty acyl-CoA. Finally the thioesterase??? (TesB) was overexpressed in the cell. In this study, a maximum of 210mg/L of hexanoic acid was produced by the engineered strain (MGREBA2) from 1g/L of oleic acid in 48hours of biotransformation. Based on these results, it is suggested that various oil as feedstock will be directly applied for the production of short chain fatty acids, especially hexanoic acid.ope

Santa Clara County Senior Nutrition Program Evaluation Report

Santa Clara County conducts a Senior Nutrition Program (SNP) in conjunction with the City of San Jose, the Outreach Paratransit Program and local community-based organizations (CBOs) like Sourcewise (Lam, 2015). These programs combined represent a significant investment of public funds, with more than 45% of the SNP program’s funding coming from the county General Fund (Lam, 2015). Such a large financial commitment needs to demonstrate some benefit to the participants, and some positive outcomes from the current program design. This study evaluated the SNP’s effectiveness in achieving its primary goals. Primary goals of the SNP are to promote senior citizens’ health and delay adverse physical and mental conditions by providing healthy meals and socialization opportunities (Lam, 2015). The program aims to provide healthy nutrition and mental stimulation for elderly residents of Santa Clara County, with the desired program outcome of better physical and mental health, enabling the participants to live independently. The focus of this study was broken into two main parts: measuring program outputs and outcomes. The study’s approach to the first part of the research questions consisted of using existing data, such as annual reports from the SNP and survey data provided by the county. The second part of the research questions used original data to analyze the program’s outcomes and impact