• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.395-406
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• 2001

In this paper, we propose the test statistic for the umbrella alternatives on c-samples ranked set samples(RSS), where the peak of the umbrella is known. We obtain the asymptotic property of the proposed test statistic and the asymptotic relative efficiencies of the proposed test statistic with respect to U-statistic based on simple random samples(SRS). From the simulation work, we compare the empirical powers of the proposed test statistic with U-statistic based on SRS.

• 한국환경보건학회지
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• 제11권2호
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• pp.29-39
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• 1985

This experimental study was carried out to evaluate the improvement of rural privys and to develop the system of the three septic tank privy. For this study, 42 samples of excreta, 42 samples of soil and 26 samples of vegetables were drawn out of the conventional privys while 26samples of excreta, 26samples of soil and 26samples of vegetables out of the three septic tank privys from five villages in Chun Song County. Kang Won Province for the period from 22th August to 13th October, 1984. The major findings are as follows : 1. Positive cases of helminthes are found 41 out of 42(97.6%) excreta of the conventional privys whereas those from the three septic tank privys are found 2 out of 26 (7.7%). Average numbers of helminthes from the excreta of the conventional privys are 4.4 whereas those from the three septic tank privys are 1.1. 2. Positive cases of helminthes are found 33 out of 42 (78.6%) soil of the conventional privys whereas those from the three septic tank privys are found 20 out of 26(76.9%). However, this difference does not reveal statistical significance (P>0.01). Average numbers of helminthes from the soil of the conventional privys are 2.3 whereas those from the three septic tank privys are 1.7 and the difference in total number of helminthes reveals statistical significance (P<0.05). 3. Positive cases of helminthes from vegetable samples drawn out of the conventional privys are found 13 out of 26(50.0%) whereas those froin the three septic tank ptivys are found 10 out of 26(38.5%). Average numbers of helminthes from vegetable samples drawn out of the conventional privys are 1.1 whereas those from the three septic tank privys are 0.7. However, these differences in both positive rates and total numbers of helminthes do not reveal statistical significance (P>0.05).

• Computers and Concrete
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• 제7권5호
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• pp.469-482
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• 2010

This paper investigates the concrete permeability through a numerical and statistical approach. Concrete is considered as a random heterogeneous composite of three phases: aggregates, interfacial transition zones (ITZ) and matrix. The paper begins with some classical bound and estimate theories applied to concrete permeability and the influence of ITZ on these bound and estimate values is discussed. Numerical samples for permeability analysis are established through random aggregate structure (RAS) scheme, each numerical sample containing randomly distributed aggregates coated with ITZ and dispersed in a homogeneous matrix. The volumetric fraction of aggregates is fixed and the size distribution of aggregates observes Fuller's curve. Then finite element method is used to solve the steady permeation problem on 2D numerical samples and the overall permeability is deduced from flux-pressure relation. The impact of ITZ on overall permeability is analyzed in terms of ITZ width and contrast ratio between ITZ and matrix permeabilities. Hereafter, 3680 samples are generated for 23 sample sizes and 4 contrast ratios, and statistical analysis is performed on the permeability dispersion in terms of sample size and ITZ characteristics. By sample theory, the size of representative volume element (RVE) for permeability is then quantified considering sample realization number and expected error. Concluding remarks are provided for the impact of ITZ on concrete permeability and its statistical characteristics.

• 분석과학
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• 제22권1호
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• pp.82-91
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• 2009

국내산 석회석을 이용하여 석회석 시료의 RRT 시험용 시료를 제조하여 XRF 및 습식 분석, ICP-OES를 이용한 기기 분석을 수행하였고 그 결과를 통계적 방법에 의하여 시료의 균질도를 평가하였다. 분석 결과 몇몇 시료의 경우 예상치 못했던 정규 분포로부터의 이상성이 발견되었으며 이상치를 제거한 후 측정한 모든 성분에 대하여 정규 분포 곡선에서 95% 신뢰 구간에서의 신뢰성 있는 표준 시료를 얻을 수 있었다.

• Communications for Statistical Applications and Methods
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• 제19권3호
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• pp.451-457
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• 2012

Baumgartner et al. (1998) proposed a novel statistical test for the null hypothesis that two independently drawn samples of data originate from the same population, and Murakami (2006) generalized the test statistic for more than two samples. Whereas the expressions of the exact density and distribution functions of the generalized Baumgartner statistic are not yet found, the characteristic function of its limiting distribution has been obtained. Due to the development of computational power, the Fourier series approximation can be readily utilized to accurately and efficiently approximate its density function based on its Laplace transform. Numerical examples show that the Fourier series method provides an accurate approximation for statistical quantities of the generalized Baumgartner statistic.

• Communications for Statistical Applications and Methods
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• 제20권2호
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• pp.147-155
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• 2013

To determine whether each coefficient is equal to zero or not, usual $t$-tests are a popular choice (among others) in linear regression to practitioners because all statistical packages provide the statistics and their corresponding $p$-values. Under smaller samples (especially with non-normal errors) the tests often fail to correctly detect statistical significance. We propose a permutation approach by adopting a sufficient dimension reduction methodology to overcome this deficit. Numerical studies confirm that the proposed method has potential advantages over the t-tests. In addition, data analysis is also presented.

• Journal of the Korean Statistical Society
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• 제30권4호
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• pp.667-678
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• 2001

The asymptotic behavior and distribution for quantiles estimators using ranked samples are introduced. Applications of quantiles estimation on finding the normal ranges (2.5% and 97.5% percentiles) and the median of some medical characteristics and on finding the Hodges-Lehmann estimate are discussed. The conclusion of this study is, whenever perfect ranking is possible, the relative efficiency of quantiles estimation using ranked samples relative to SRS is high. This may translates to large savings in cost and time. Also, this conclusion holds even if the ranking is not perfect. Computer simulation results are given and real data from lows 65+ study is used to illustrate the method.

• Communications for Statistical Applications and Methods
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• 제16권6호
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• pp.1055-1066
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• 2009

Many articles have considered a hybrid censoring scheme, which is a mixture of Type-I and Type-II censoring schemes. We introduce a double hybrid censoring scheme and derive some approximate maximum likelihood estimators(AMLEs) of the scale parameter for the half logistic distribution under the proposed double hybrid censored samples. The scale parameter is estimated by approximate maximum likelihood estimation method using two different Taylor series expansion types. We also obtain the maximum likelihood estimator(MLE) and the least square estimator(LSE) of the scale parameter under the proposed double hybrid censored samples. We compare the proposed estimators in the sense of the mean squared error. The simulation procedure is repeated 10,000 times for the sample size n = 20(10)40 and various censored samples. The performances of the AMLEs and MLE are very similar in all aspects but the MLE and LSE have not a closed-form expression, some numerical method must be employed.

• Journal of the Korean Statistical Society
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• 제25권1호
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• pp.145-151
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• 1996

The local behaviour of the surface formed by the perturbed maximum likelihood estimator of the squared Mahalanobis distance is investigated. The study of the local behaviour allows a simultaneous perturbation on the samples of interest and it is effective in identifying influential observations.

• Journal of the Korean Statistical Society
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• 제12권1호
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• pp.36-45
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• 1983

After every decennial census in the U.S., national surveys such as the Consumer Expenditures surveys are redesigned. The redesigned samples will be multi-stage systematic samples. Many sampling schemes have been proposed for comparison which requires the estimation and variance estiamtion formula. This paper deals with the surveys redesign research which concerns the sample design within the Primary Sampling Unit (PSU). In constructing the estimators it deals with the problem of which first stage inflation factor to use. The expected value of the proposed estimators is also derived.