• Journal of the Korean Statistical Society
• /
• 제36권1호
• /
• pp.93-109
• /
• 2007

Gamma distributions are some of the most popular models for hydrological processes. In this paper, a very flexible family which contains the gamma distribution as a particular case is introduced. Evidence of flexibility is shown by examining the shape of its pdf and the associated hazard rate function. A comprehensive treatment of the mathematical properties is provided by deriving expressions for the nth moment, moment generating function, characteristic function, Renyi entropy and the asymptotic distribution of the extreme order statistics. Estimation and simulation issues are also considered. Finally, a detailed application to drought data from the State of Nebraska is illustrated.

• 한국지형학회지
• /
• 제21권4호
• /
• pp.133-147
• /
• 2014

애추와 같이 인간의 접근이 쉽지 않은 지형의 현장조사에서는 시간과 비용을 절약하기 위해 실제 현장조사 전에 대상 지형자원의 범위를 줄이는 방법이 요구된다. 본 연구에서는 대상 지형자원의 현장조사 범위를 줄이기 위해 기존 지형의 위치와 기타 GIS 정보 사이의 관계를 확률로 표현하는 자료유도형(target-driven) 공간통계기법인 Weight of Evidence 기법을 적용하였다. Weight of Evidence 기법을 적용하기 위해 애추와 관련된 지형요소를 선정한 후 지형요소와 GIS 정보의 상관관계 분석 결과를 근거로 우도비를 산출하였다. 각각의 주제도에 대한 경우의 수를 산정한 후, SRC 및 AUC 방법을 이용하여 애추 분포 가능지수가 가장 큰 조합을 찾았다. 애추 분포 가능지수가 가장 큰 주제도의 조합은 사면향도와 지질도, 경사도, 토지피복도, 유효토심도, 토양배수도의 조합으로, 애추 분포 가능지 면적비가 74.47%로 나타나 상당히 높은 정확도를 보였다.

• Journal of Acupuncture Research
• /
• 제19권3호
• /
• pp.138-155
• /
• 2002

Objective : The purpose of this study is to work on the problems and on the direction of the study regarding the evidence-based study of Acupuncture. Methods : We reviewed the PubMed electronic database. Eight articles of systematic review without meta-analysis and six articles without meta-analysis were selected. Results : In the study of eight articles of systematic review without meta-analysis, there were two articles on effectiveness of acupuncture and one on non-effectiveness of acupuncture. Four articles were about the changes according to the quality of randomized controlled trials. Also, one article was about the side-effect of acupuncture. In the study of six articles of systematic review with meta-analysis, there were two articles on Odds Ratio, two on Relative Risk, one on number-needed-to-treat, and two on 18 predefined methodological criteria. Conclusion : As the quality of RCTs was high, positive response decreased and as the quality of RCTs was low, positive response increased. For the study of evidence-based acupuncture, it is necessary that we conduct research on well-planned placebo acupuncture, large sample size, statistical method, method of searching and assessing literature and method of meta-analysis.

• 아태비즈니스연구
• /
• 제11권4호
• /
• pp.37-48
• /
• 2020

Purpose - This study empirically investigates whether the risk property included in fat-tails of return distributions is systematic or unsystematic based on the devised statistical methods. Design/methodology/approach - This study devised empirical designs based on two traditional methods: principal component analysis (PCA) and the testing method of portfolio diversification effect. The fatness of the tails in return distributions is quantitatively measured by statistical probability. Findings - According to the results, the risk property in the fat-tails of return distributions has the economic meanings of eigenvalues having a value greater than 1 through PCA, and also systematic risk that cannot be removed through portfolio diversification. In other words, the fat-tails of return distributions have the properties of the common factors, which may explain the changes of stock returns. Meanwhile, the fatness of the tails in the portfolio return distributions shows the asymmetric relationship of common factors on the tails of return distributions. The negative tail in the portfolio return distribution has a much closer relation with the property of common factors, compared to the positive tail. Research implications or Originality - This empirical evidence may complement the existing studies related to tail risk which is utilized in pricing models as a common factor.

• 한국빅데이터학회지
• /
• 제6권2호
• /
• pp.61-70
• /
• 2021

본 연구의 목적은 개별연구들이 정확한 통계량을 제시하지 않고 그래프로만 나타내었을 경우 그래프로부터 통계량을 추출해내는 구체적인 방법을 기술한 것으로서 데이터통합과 정량적합성을 위한 메타분석을 가능하게 한다. 특히 메타분석(meta-analysis)은 체계적·객관적으로 대상문헌을 선택한 후 개별 연구들의 결과를 계량화하여 이를 통합된 효과크기(effect size)로 제시함으로써 근거중심의학(evidence based medicine)를 위한 올바른 의사결정을 할 수 있게 하는 중요한 분석도구이다. 데이터통합과 메타분석을 위해서 그래프로부터 정확한 통계수치를 추출하는 전산도구인 Adobe Acrobat Reader 와 Python기반의 JupyterLab 소프트웨어의 소개와 적용에 대한 주요사항을 알아보았다. 사용된 예제자료는 선행연구를 통해서 통계결과가 검증되어졌고 ClinicalTrials.gov에서 원자료 확보가 가능한 것을 사용하였다. 원자료와 각 전산도구들의 측정값을 각각 메타분석한 결과 통계적으로 유의한 차이는 없었다. 또한 연구자들간의 측정 신뢰도를 확인하였으며 높은 일치도를 나타내었다. 만약 그래프로부터 통게수치를 추출해야만 할 경우 연구의 완결성 유지를 위해서 전통적 사용 방법들보다는 전산 도구를 이용한 측정이 권고된다.

• Communications for Statistical Applications and Methods
• /
• 제16권2호
• /
• pp.373-381
• /
• 2009

Evidence of linkage is expressed as a decreasing trend of the squared trait difference of two siblings with increasing identical by descent scores. In contrast to successes in the application of a parametric approach of Haseman-Elston regression, notably low powers are demonstrated in the nonparametric linkage analysis methods for complex traits and diseases with sib-pairs data. We report that the Genehunter nonparametric linkage statistic is biased and furthermore the variance formula that they used is an inflated one, and this is one reason for a low performance. Thus, we propose bias-corrected nonparametric linkage statistics. Simulation studies comparing our proposed nonparametric test statistics versus the existing test statistics suggest that the bias-corrected new nonparametric test statistics are more powerful and attains efficiencies close to that of Haseman-Elston regression.

• Communications for Statistical Applications and Methods
• /
• 제28권6호
• /
• pp.583-594
• /
• 2021

In this paper, we propose wavelet-based procedures to identify the difference between images, including portraits and handwriting. The proposed methods are based on a novel combination of multiscale methods with a regularization technique. The multiscale method extracts the local characteristics of an image, and the distinct features are obtained through the regularized regression of the local characteristics. The regularized regression approach copes with the high-dimensional problem to build the relation between the local characteristics. Lytle and Yang (2006) introduced the detection method of forged handwriting via wavelets and summary statistics. We expand the scope of their method to the general image and significantly improve the results. We demonstrate the promising empirical evidence of the proposed method through various experiments.

• 한국콘텐츠학회논문지
• /
• 제18권3호
• /
• pp.626-635
• /
• 2018

점차 심각해지고 있는 중국 청소년 비만예방 메시지 개발을 위해 본 연구는 비만 관여도과 메시지 프레이밍 유형 간의 상호작용, 비만 관여도와 증거 유형 간의 상호작용이 비만예방 태도와 행동의도에 미치는 영향을 살펴보았다. 메시지 프레이밍 유형은 이익 프레이밍과 손실 프레이밍으로 구분하였고, 증거는 개인 경험을 바탕으로 하는 내러티브와 객관적 수치에 기반한 통계적 형식으로 구분하였다. 중국 청소년 368명이 참여한 연구 분석 결과 수용자의 관여도, 메시지 프레이밍과 증거 유형이 비만예방 태도와 행동의도에 유의미한 영향을 보였다. 관여도가 높은 집단은 손실 프레임과 통계적 증거에 노출되었을 때 더 긍정적 비만예방 태도와 행동의도를 보이는 것으로 나타났다. 관여도가 낮은 집단은 이익 프레임과 내러티브에 노출되었을 때 더 긍정적 비만예방 태도와 행동의도를 보이는 것으로 나타났다. 따라서 관여도가 높은 집단을 설득하기 위해서는 통계에 바탕을 둔 손실프레이밍을, 관여도가 낮은 집단을 설득하기 위해서는 내러티브에 바탕을 둔 이익프레이밍을 제시할 것을 제안한다.

• 한국유기농업학회지
• /
• 제30권1호
• /
• pp.21-35
• /
• 2022

Measuring the food safety has been focused only on the psychological consumers' recognition of food safety. The actual measurement tool should consist of the evidence-based statistical data to assess the level of national food safety in scientific perspectives. This paper described the development of a concept to measure the food safety of the food chain based on OECD PSR framework. This paper discusses the elaboration of a set of 8 food safety related data issued as statistical data, and which were same weighted. These food safety statistical data (FSDs) were derived as the basis of measuring the variation of food safety during 2013-2019. The values of the primary production indicator (PPI), the processing and manufacturing indicator (PMI), and the distribution and consumption indicator (DCI) are 0.558-0.859, 0.533-0.691, and 0.979-0.982, respectively. The food safety status (FSS) derived from the safety indicator values of each of the three stages is 0.700-0.810. In order to increase the level of food safety, it is necessary to pay attention to PMI and PPI management. In the future, continuously calculating the level of food safety, managing it like the level of psychological safety, and further expanding it to the level of food safety between countries will help establish policies to improve the level of food safety in Korea.

• Communications for Statistical Applications and Methods
• /
• 제29권5호
• /
• pp.547-559
• /
• 2022

For a chi-squared test, which is a statistical method used to test the independence of a contingency table of two factors, the expected frequency of each cell must be greater than 5. The percentage of cells with an expected frequency below 5 must be less than 20% of all cells. However, there are many cases in which the regional expected frequency is below 5 in general small area studies. Even in large-scale surveys, it is difficult to forecast the expected frequency to be greater than 5 when there is small area estimation with subgroup analysis. Another statistical method to test independence is to use the Bayes factor, but since there is a high ratio of data dependency due to the nature of the Bayesian approach, the low expected frequency tends to decrease the precision of the test results. To overcome these limitations, we will borrow information from areas with similar characteristics and pool the data statistically to propose a pooled Bayes test of independence in target areas. Jo et al. (2021) suggested hierarchical Bayesian pooling models for small area estimation of categorical data, and we will introduce the pooled Bayes factors calculated by expanding their restricted pooling model. We applied the pooled Bayes factors using bone mineral density and body mass index data from the Third National Health and Nutrition Examination Survey conducted in the United States and compared them with chi-squared tests often used in tests of independence.