• Restorative Dentistry and Endodontics
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• 제42권2호
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• pp.152-155
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• 2017

• 유통과학연구
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• 제14권7호
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• pp.5-14
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• 2016

Purpose - This paper studies if types of markets have an association with several variables such as occupation, district, sales, employee, administrative district by a lessor, area in rental building and so on. Three attributes of markets can be general commercial zones, central commercial zones and traditional markets. Furthermore, we can investigate the degree of association by calculating the numerical strength and visualizing their distances on two-dimensional plane, once the association exists between them. Research design, data, and methodology - This work is performed by the 2013 report presented with Small Businessmen Promotion Institute in Korea and used by a chi-squared test and correspondence analysis by using IBM SPSS 23.0. Results - The results show that types of markets, including traditional markets, have an association with variables considered in this paper, and we can obtain the detailed associations between attributes of corresponding variables by inspecting two-dimensional plane. Conclusions - This study suggests that government authority and local autonomy can make strategies to vitalize traditional markets and to get win-win relationships among several types of markets by looking over our findings.

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

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2005년도 춘계학술대회
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• pp.182-184
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• 2005

In this study, we propose a chi-squared test of spherical symmetry. The advantage of this test is that the test statistic and its asymptotic p-value are easy to compute. A simulation study is conducted to study the accuracy, in finite samples, of the limiting distribution of the test statistic under spherical symmetry. The power of our test is compared with those of other tests for spherical symmetry in various alternative distributions via simulation.

• Journal of the Korean Data and Information Science Society
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• 제17권1호
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• pp.115-122
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• 2006

A test is suggested for detecting deviations from both multivariate normality and independence. This test can be used for assessing the normality and independence of univariate time series residuals. We derive the limiting distribution of the test statistic and a simulation study is conducted to study the accuracy of the limiting distribution in finite samples. Finally, we apply our method to a real data of time series.

• Journal of the Korean Data and Information Science Society
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• 제23권4호
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• pp.757-764
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• 2012

복합표본설계에 기초한 범주형 조사자료는 통상적인 피어슨 카이제곱검정에 필요한 조건을 만족하지 못한다. 그러나 많은 조사연구에서 복잡한 표본설계 방법을 적용하고 있지만, 종래의 피어슨 검정결과를 제시하고 있다. 본 연구는 복합표본설계에 의한 범주형자료의 동질성검정에 대한 실증분석을 통해, 종래의 피어슨 검정과 불편검정인 왈드검정, 표본설계를 반영한 비율추정치를 사용하는 피어슨 검정을 비교하였다. 분석결과, 종래의 피어슨검정은 표본설계를 반영하는 검정들에 비해 통계량 값이 매우 크고, 유의확률이 심각하게 작게 나타나는 것을 확인하였다. 복합표본설계를 반영하되 추정량의 분산을 아는 경우와 모르는 경우의 비교에서는 범주수, 설계효과행렬의 고유치들의 평균과 표준편차에 영향을 받는 것을 확인하였다.

• Communications for Statistical Applications and Methods
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• 제8권1호
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• pp.51-63
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• 2001

We are interested in the conditional independence in sparse $2\tims2\tims$K tables with very rare cell counts. The most popular test is Cochran-Mantel-Haenszel statistic when sample sizes are moderately large enough to guarantee the chi-square approximation. We will consider jackknifing the CMH test and also suggest an approximate normal distribution for the standardized jackknifed CMH statistic. The main focus of this paper is to improve the chi-squared approximation to the CMH test by using the asymptotic normality of the jackknifed CMH test when sample sizes are very sparse but K and N$\infty$. The performance of the proposed jackknifed test, in the sense of significance level control and power, will be compared with that of the CMH test through a Monte Carlo study.

• Communications for Statistical Applications and Methods
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• 제19권3호
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• pp.495-500
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• 2012

We consider a Bayesian test of independence in a two-way contingency table that has some zero cells. To do this, we take a three-stage hierarchical Bayesian model under each hypothesis. For prior, we use Dirichlet density to model the marginal cell and each cell probabilities. Our method does not require complicated computation such as a Metropolis-Hastings algorithm to draw samples from each posterior density of parameters. We draw samples using a Gibbs sampler with a grid method. For complicated posterior formulas, we apply the Monte-Carlo integration and the sampling important resampling algorithm. We compare the values of the Bayes factor with the results of a chi-square test and the likelihood ratio test.

• 해양환경안전학회지
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• 제24권3호
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• pp.339-345
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• 2018

Sunrise and sunset times differ depending on location and date. Previous studies conveniently but monotonously applied day and night times set up. This research defined the daytime and nighttime while considering the time of twilight according to the date and the location of ship collision accidents. Classifying the frequency of ship collision accidents with this standard, we conducted a chi-squared test for the difference between daytime and nighttime. The frequencies of ship collision accidents according to daytime and nighttime was compared by season, month, and time, and all of them showed statistically significant differences. The highest number of daytime ship collisions was 11.6 %, in June, and nighttime collisions peaked at 13.7 %, in December. The most frequent hour for daytime ship collisions was 0700h-0800h, at 10.2 %, and nighttime collisions peaked between 0400h-0500h, at 16.9 %. It is clear that the criteria used in previous studies cited was applied without any theoretical basis and likely only for the convenience of the researchers. It was found that results depend on what criteria are applied to the same research data. This study shows that statistical analyses of marine accidents, traffic volume, and congestion density should be carried out quantitatively while considering daytime and nighttime hours for each particular location and date.

• 산경연구논집
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• 제7권3호
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• pp.5-12
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• 2016

Purpose - In this paper, we consider more segmented types of markets than conventional version of ones in South Korea and explore the degree of relations between these markets and the related factors with them. In this case, ten attributes of types of markets mentioned above will be considered. To be more specific, the numerical strength is evaluated and graphical approach is expressed on two-dimensional plane, if the association exists between the considered variables. Research design, data, and methodology - This work is done by the 2013 report on the commercial building lease offered by Small Businessmen Promotion Institute (May/2013~August/2013) and exploited by statistical analyses such as correspondence analysis and a chi-squared test in IBM SPSS 23.0. Results - Findings of this paper indicate that a variable Korean market, including traditional markets, are closely connected with variables administrative district, sales and occupation instead of company, age group and business duration and the detailed associations between variables can be obtained by inspecting results of correspondence analysis. Conclusions - We can understand where the status of the Korean markets stands now through this work and also government authority and local autonomy can take advantage of these findings to enhance the revitalization of Korean markets and other markets.