• Title/Summary/Keyword: two-sample problem

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Long-Run Exchange Rates, Price Levels, and Purchasing Power Parity: Cointegration Tests of Five Korea Trading Partners' Currencies

  • Gong, Jai-Sik
    • The Korean Journal of Financial Studies
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    • v.6 no.1
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    • pp.313-334
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    • 2000
  • In this paper, we obtained some supportive evidence for the long-run PPP relationship concerning the Korean Won currency. Previous tests of PPP in the bilateral exchange rates of the Korean Won rate vis-a-vis the U.S. Dollar have been exposed to the lack of power problem. We argue that their failure to find PPP relation in Korean Won rates was due to the low power of Augmented Dickey-Fuller tests or the Engle-Granger two-step tests applied to the Korean exchange rate data with short sample period. En attempting to alleviate this low power problem, we used the error-correction model test and the Johansen test for bilateral long-run equilibrium relationships between exchange rates and price indices from Korea's major trading partners. It is surprising that our evidence supporting for long-run PPP in Korean Won rate contrasts sharply with Bahmani-Oskooee, Moshen and Rhee, Hyun-Jae(1992)'s.

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An Optimal Parameter Selection of Power System Stabilizer using Immune Algorithm (면역 알고리즘을 이용한 전력 계통 안정화 장치의 최적 파라미터 선정)

  • Jeong, Hyeong-Hwan;Lee, Jeong-Pil;Jeong, Mun-Gyu;Lee, Gwang-U
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.9
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    • pp.433-445
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    • 2000
  • In this paper, optimal tuning problem of power system stabilizer(PSS) using Immune Algorithm(IA) is investigated to improve power system dynamic stability. In proposed method, objective function is represented as antigens. An affinity calculation is embedded within the algorithm for determining the promotion or suppression of antibody. An antibody that most fits the antigen is considered as the solution to PSS tuning problem. The computaton performance by the proposed method is compared with Genetic Algorithm(GA). The porposed PSS using IA has been applied for two sample system, single-machine infinite bus system and multi-machine power system. The performance of the proposed PSS is compared with that of conventional PSS. It is shown that the proposed PSS tuned using immune algorithm is more robust than conventional PSS.

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A study on the method for distinguishing general from science-inclined learners by using Pattern Recognition (패턴인식을 이용한 과학영재 판별 도구에 관한 연구)

  • Bang, Seung-Jin;Choi, Jung-Oh;Kim, Hyouk
    • Communications of Mathematical Education
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    • v.20 no.4 s.28
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    • pp.551-559
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    • 2006
  • Pattern Recognition measures the ability of learners to distinguish between two sets of shapes or figures. Locating similar patterns on either side of the presented problem determines a learner's capacity or aptitude for science over general studies. At Ajou University's Institute for Scientifically Enabled Youth, we conducted research using a sample composed of middle school students with general and scientific backgrounds. The result proved that Pattern Recognition measures a different creative talent other than problem solving. In our opinion, Pattern Recognition would be a method better suited to elementary learners over those in middle or high school.

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A Forecasting System for KOSPI 200 Option Trading using Artificial Neural Network Ensemble (인공신경망 앙상블을 이용한 옵션 투자예측 시스템)

  • 이재식;송영균;허성회
    • Proceedings of the Korea Inteligent Information System Society Conference
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    • 2000.11a
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    • pp.489-497
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    • 2000
  • After IMF situation, the money market environment is changing rapidly. Therefore, many companies including financial institutions and many individual investors are concerned about forecasting the money market, and they make an effort to insure the various profit and hedge methods using derivatives like option, futures and swap. In this research, we developed a prototype of forecasting system for KOSPI 200 option, especially call option, trading using artificial neural networks(ANN), To avoid the overfitting problem and the problem involved int the choice of ANN structure and parameters, we employed the ANN ensemble approach. We conducted two types of simulation. One is conducted with the hold signals taken into account, and the other is conducted without hold signals. Even though our models show low accuracy for the sample set extracted from the data collected in the early stage of IMF situation, they perform better in terms of profit and stability than the model that uses only the theoretical price.

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The Effect of Payment Method of Community Medical Provider on Medical Care Use of Community Residents (지역사회 의료공급자의 지불보상체계상의 특징이 지역사회 주민의 의료이용에 미치는 영향: 미국사례분석)

  • Lim, Jae-Young
    • Health Policy and Management
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    • v.15 no.2
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    • pp.16-36
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    • 2005
  • Due to the existence of asymmetry of information between doctor and patient, it has been believed that doctor might affect patient's decision making process of purchasing medical care. Based on this notion, doctor's reimbursement method has been suggested as an effective policy device of improving efficiency of patient's medical care use by way of its affecting doctor's practice pattern. By using the Community Tracking Study (CTS) household and physician data set, which includes not only various information on patient's medical care use, but doctor's practice arrangements and sources of practice revenue, this paper investigates the effect of community doctor's characteristics of reimbursement method on community patient's medical care use under the control of patient's socio-demographic characteristics and community doctor's practice type. In the process of estimating econometric model, the endogeneity problem of individual health insurance purchase was corrected by using 2818. And due to the existence of sample selection problem, Heckman's two-step estimation method was used for strengthen the robustness of estimation which was adversely affected by sample selection problem The empirical results show that as the average value of community doctor's portion of practice revenue determined by prospective method out of total revenue increases, the community patient's total out-of-pocket medical cost decreases. This results suggest, as doctor's practice revenues are mainly determined by prospective method, such as capitation, doctors would be more conscious about practice cost, which might affect doctor's practice pattern and by which his/her patient's use of medical care would decrease.

The Effects of 'Reading Guide' Course through Problem-Based Learning on Problem Solving Ability and Communication Ability (프로젝트 기반 학습법을 통한 '독서지도' 과목이 문제해결능력과 의사소통능력에 미치는 영향)

  • Lee, Myeong-Hee
    • Journal of the Korean Society for Library and Information Science
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    • v.54 no.1
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    • pp.197-221
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    • 2020
  • This study investigates the influence of project-based learning method on the problem-solving ability and communication ability of students taking the 'Reading Guide' course in Library and Information Science(LIS). During this study, two tests measuring students' problem-solving ability and communication ability were conducted, containing 30 items divided into 5 steps of problem-solving processes and 45 items divided into 15 categories of communication ability, respectively. By utilizing the correspondence sample T-test during this study, significant differences were found in the 5 steps problem-solving processes. However, no difference was found between the pre-test and the post-test results in all 15 categories of communication ability. Subsequently, an in-depth interview was conducted, inquiring into the students' perspectives on the difficulty of attending classes, the content of lectures, the appropriateness of assignments, the validity of the evaluation method, the relationship with their team members, and the benefits acquired from completing the projects. Finally, an intensive analysis was conducted in the categories of problem-solving ability and communication ability.

Effects of a Critical Thinking Course for Korean Nurses in RN-BSN Program

  • Je, Nam-Joo;Lee, Shin-Young;Lee, Seonah
    • Journal of Integrative Natural Science
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    • v.12 no.2
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    • pp.58-68
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    • 2019
  • Critical thinking is essential to implementing the nursing process requiring timely decision making. The study examined the effects of a critical thinking course for nurses in the RN-BSN program. The study used a pre- and post-test design with a control group. The experimental group was a convenience sample of 24 working nurses attending a health college. The control group was 24 fellow nurses. The nursing process-based critical thinking course was provided to the experimental group two and half hours a week for 8 weeks. Teaching methods included lectures followed by a summary and quiz, brainstorming and action learning, and lecturer feedback. A pamphlet about views of professional occupation was provided to the control group. The data were collected using self-report questionnaires and analyzed to examine differences in the test scores before and after the intervention. The scores of critical thinking disposition, problem-solving process, and clinical competence increased significantly in the experimental group but did not in the control group. The difference between the two groups was also statistically significant in critical thinking disposition, problem-solving process, and clinical competence. It is necessary that a robust educational program or training to enhance critical thinking ability of nurses are provided in clinical settings and that nurses keep going on thinking critically in their practice.

Similarity Analysis of Exports Value Added by Country and Implication for Korea's Global Value Added Chains

  • Cho, Jung-Hwan
    • Journal of Korea Trade
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    • v.23 no.4
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    • pp.103-114
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    • 2019
  • Purpose - This paper investigates the structure of exports across countries in terms of value added. Exports value added is examined under two categories, domestic and overseas. Using a statistical classification method by distance based on these two value added categories, this paper estimates the similarity of exports value added across countries including Korea. Design/methodology - The model of study is to employ a generalized distance function and then derive the Manhattan and Euclidean distances. The paper also performs cluster analysis using the Partitioning Around Medoids (PAM) and hierarchical methods to classify the 44 sample countries considered in this study. Findings - Our main findings are as follows. The 44 countries can be classified under 5 groups by their domestic and overseas value added in exports. Korea has a sandwich global value chains (GVCs) position between Japan, China, and Taiwan in the East Asian region. Originality/value - Existing papers point out the double counting problem of trade statistics as the intermediate goods trade across borders increases. This paper addresses the double counting problem by using the World Input-Output Table. The paper shows the need to explore the similarity of value added in exports structure across countries and investigate the GVCs position and role of each country.

Comparative Analysis on Learning Strategies, Motivation, Beliefs in Ability, and Problem Solving Patterns of the Gifted Achievers and the Gifted Underachievers in Elementary School (성취영재와 미성취영재는 어떻게 다른가?: 학습전략, 동기, 능력신념, 그리고 문제해결성향의 차이분석)

  • Han, Ki-Soon;Shin, Jeong-A
    • Journal of Gifted/Talented Education
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    • v.17 no.1
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    • pp.27-50
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    • 2007
  • The purpose of this study was to examine whether gifted achievers and gifted underachievers differ in their learning strategies, motivation, beliefs in ability, and problem solving patterns. The sample for the study consisted of 68 gifted achievers and 34 gifted underachievers who were in 5th and 6th grades in elementary schools in the metropolitan area. Gifted achievers and gifted underachievers showed statistically significant differences in all aspects using the independent sample t-test. In addition, the discriminant analysis correctly classified over 77.5% of the sample as either gifted achievers or gifted underachievers using the variables used in the study, indicating factors related to learning strategies can be effective measures to identify gifted achievers and underachievers. Especially, extrinsic motivation and problem solving patterns were the most discriminant factors in these two groups. The implications of the study related to the identification and education of the gifted underachievers were discussed in depth.

Weight, Self-esteem, and Depression in High School and College Females (여고생과 여대생의 체중, 자아존중감 및 우울에 대한 비교 연구)

  • Kim, Ok Soo;Kim, Kye Ha
    • Korean Journal of Adult Nursing
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    • v.12 no.3
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    • pp.396-406
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    • 2000
  • The purpose of the study was to investigate Body Mass Index (BMI), the perception of weight problem and the level of self-esteem and depression in high school and college females. The convenience sample consisted of 303 high school females and 481 college females. Data were collected between November 1999 and December 1999. Subjects ranged in age from 15 years and 26 years. BMI was calculated based on the subject's self-reported body weight and height. Self-perception of having a weight problem was evaluated by a single item question. The Rosenberg's Self-Esteem Scale and the Center for Epidemiologic Studies Depression Scale were utilized to measure the level of self-esteem and depression symptoms. BMI mean scores were 19.92 and 19.83 in high school females and college females, respectively. Based on BMI, 79.2 percent of high school females and 85.2 percent of college females were in a normal weight range. Only 2.6 percent of high school females and 1.5 percent college females were obese. Both high school and college females perceived their body weight problem as moderately severe. The mean scores of depression were 20.33 in high school females and 21.69 in college females. Sixty percent of high school females were depressed and 73.4 percent of college students. There was no significant difference between two groups in BMI. However, high school females perceived their weight problem more severe than college females. College females had higher levels of self-esteem and depression than high school females. BMI and perceptions of weight problem revealed a positive relationship in both groups. Results of the study revealed that a perception of weight problem contributed significantly to predict the level of self-esteem and depression in both groups. BMI score had significant effect on only college females' self-esteem. In the study, even though the mean score of BMI was in a normal range, subjects perceived their weight problems as moderatley severe. Since the perception of a weight problem influenced the level of self-esteem and depression, health care providers need to teach them about the normal weight range in BMI criteria.

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