• 제목/요약/키워드: Statistical Procedures

검색결과 686건 처리시간 0.024초

Nonparametric Tests for Monotonicity Properties of Mean Residual Life Function

  • Jeon, Jong-Woo;Park, Dong-Ho
    • Journal of the Korean Statistical Society
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    • 제26권1호
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    • pp.101-116
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    • 1997
  • This is primarily an expository paper that presents several nonparametric procedures for testing exponentiality against certain monotonicity properties of the mean residual life function, tests against the trend change in such function attract a great deal of attention of late in reliability analysis. In this note, we present some of the known testing procedures regarding the behavior of mean residual life function. These tests are also compared in terms of asymptotic relative efficiency and empirical power against a few alternatives. The tests based on incomplete data are also briefly discussed.

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Unified methods for variable selection and outlier detection in a linear regression

  • Seo, Han Son
    • Communications for Statistical Applications and Methods
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    • 제26권6호
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    • pp.575-582
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    • 2019
  • The problem of selecting variables in the presence of outliers is considered. Variable selection and outlier detection are not separable problems because each observation affects the fitted regression equation differently and has a different influence on each variable. We suggest a simultaneous method for variable selection and outlier detection in a linear regression model. The suggested procedure uses a sequential method to detect outliers and uses all possible subset regressions for model selections. A simplified version of the procedure is also proposed to reduce the computational burden. The procedures are compared to other variable selection methods using real data sets known to contain outliers. Examples show that the proposed procedures are effective and superior to robust algorithms in selecting the best model.

염소이온 확산계수의 확률변수 평가 (Estimation of Probability Valuable for Diffusion Coefficient of Chloride Ion)

  • 배수호;이광명;김지상;정상화
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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    • pp.515-518
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    • 2005
  • In recent years, many research works have been carried out in order to obtain a more controlled durability and long-term performance of concrete structures exposed to chloride environments. In particular, the development of new procedures for probability-based durability analysis and design has been proved to be very valuable. To carry out the procedures described above, the statistical properties of design valuables such as diffusion coefficient of chloride ion, surface chloride concentration, and chloride threshold value etc. should be known. For this purpose, this paper presents the statistical properties of the diffusion coefficient of chloride ion such as mean value and standard deviation with water-cement(w/c) ratio and curing conditions, respectively. It was observed from the test that the standard deviation for the diffusion coefficient of chloride ion was found to be small with decrease in the w/c ratio irrespective of curing conditions and that of standard curing was found to be smaller than that of field curing.

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破壤檢査詩의 最小費용 샘플링 檢査方式 (A minimum cost sampling inspection plan for destructive testing)

  • 趙星九;裵道善
    • Journal of the Korean Statistical Society
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    • 제7권1호
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    • pp.27-43
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    • 1978
  • This paper deals with the problem of obtaining a minimum cost acceptance sampling plan for destructive testing. The cost model is constructed under the assumption that the sampling procedure takes the following form; 1) lots rejected on the first sample are acreened with a non-destructive testing, 2) the screening is assumed to be imperfect, and therefore, after the screening, a second sample is taken to determine whether to accept the lot of to scrap it. The usual sampling procedures for destructive testing can be regarded as special cases of the above one. Utilizing Hald's Bayesian approach, procedures for finding the global optimal sampling plans are given. However, when the lot size is large, the global plan is very different to obtain even with the aid of an electronic computer. Therefore a method of finding suboptimal plan is suggested. An example with uniform prior is also given.

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A Study on Sampling Methods in Rice Yield Survey

  • Park, Hong-Nai
    • Journal of the Korean Statistical Society
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    • 제4권1호
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    • pp.19-33
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    • 1975
  • The Ministry of Agriculture and Fishery had carried out a random sample survey on rice yield by the method of plot cutting since 1959 to obtain correct statistics on rice production. There are important problems connected with the determination of optimum size and shape of sample plot, variation of yield between plots and field and variation in the time needed for different types of plot cutting. This kind of research has been performed in India by Dr. P. V. Sukhatme and Dr. V. G. Panse. Also the same optimum procedures are much different in Japan that in India. In Korea, the optimum procedures may well be different from either of these countries. Although the government is proceeding with the crop yield survey, it does not attempt to investigate plot problems but emphasize total rice yield estimation. This particular research was conducted on a scale enough that the author could personally supervise all of the work.

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Penalized variable selection for accelerated failure time models

  • Park, Eunyoung;Ha, Il Do
    • Communications for Statistical Applications and Methods
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    • 제25권6호
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    • pp.591-604
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    • 2018
  • The accelerated failure time (AFT) model is a linear model under the log-transformation of survival time that has been introduced as a useful alternative to the proportional hazards (PH) model. In this paper we propose variable-selection procedures of fixed effects in a parametric AFT model using penalized likelihood approaches. We use three popular penalty functions, least absolute shrinkage and selection operator (LASSO), adaptive LASSO and smoothly clipped absolute deviation (SCAD). With these procedures we can select important variables and estimate the fixed effects at the same time. The performance of the proposed method is evaluated using simulation studies, including the investigation of impact of misspecifying the assumed distribution. The proposed method is illustrated with a primary biliary cirrhosis (PBC) data set.

Fixed-accuracy confidence interval estimation of P(X > c) for a two-parameter gamma population

  • Zhuang, Yan;Hu, Jun;Zou, Yixuan
    • Communications for Statistical Applications and Methods
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    • 제27권6호
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    • pp.625-639
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    • 2020
  • The gamma distribution is a flexible right-skewed distribution widely used in many areas, and it is of great interest to estimate the probability of a random variable exceeding a specified value in survival and reliability analysis. Therefore, the study develops a fixed-accuracy confidence interval for P(X > c) when X follows a gamma distribution, Γ(α, β), and c is a preassigned positive constant through: 1) a purely sequential procedure with known shape parameter α and unknown rate parameter β; and 2) a nonparametric purely sequential procedure with both shape and rate parameters unknown. Both procedures enjoy appealing asymptotic first-order efficiency and asymptotic consistency properties. Extensive simulations validate the theoretical findings. Three real-life data examples from health studies and steel manufacturing study are discussed to illustrate the practical applicability of both procedures.

Human Corneal Endothelial 패턴의 통계적 분석을 위한 광전자적 방법 (Optical-Electronic Method for Statistical Evaluation of Human Corneal Endothelial Patterns)

  • 이임걸
    • 대한의용생체공학회:학술대회논문집
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    • 대한의용생체공학회 1992년도 추계학술대회
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    • pp.58-62
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    • 1992
  • Hybrid optical-electronic procedures are introduced for the automated estimation of cell parameters (e.g., size, size variation, and shape). Two different optical Fourier analysis procedures are applied to high contrast cell boundary patterns obtained from specular micrographs of the endothelial layer. In one case, a large number of cell patterns are illuminated to extract average cell size information. Once the average cell size information has been obtained, individual cells are illuminated to extract shape information.

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WTO/TBT 협정에 따른 KS 규격의 부합화에 관한 연구 (A Study on the Conformity of KS Standards according to Agreement on WTO/TBT)

  • 김진규
    • 산업경영시스템학회지
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    • 제26권4호
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    • pp.12-22
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    • 2003
  • The purposes of this study are to investigate the conformity of Korean Standards(KS) according to agreement on WTO/TBT, and to propose systematic frameworks of preparation, adoption, and application for KS in our enterprises. Significant changes in this establishment, revision, and abrogation include the following divisions; i) statistics-vocabulary and symbols, ii) Shewhart control chart, iii) statistical interpretation of data, iv) sampling procedures for inspection by attributes, v) sequential sampling plans for inspection.

3개의 모수영역을 모니터링하는 EWMA 관리도 (EWMA control charts for monitoring three parameter regions)

  • 김유경;이재헌
    • 응용통계연구
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    • 제35권6호
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    • pp.725-737
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    • 2022
  • 통계적 공정 모니터링에서 관리 상태일 때 품질 특성치의 모수값은 하나의 값으로 지정하는 경우가 대부분이다. 그러나 관리 상태로부터 공정 모수의 작은 변화는 실제적으로 크게 중요하지 않은 경우, 품질 특성치의 모수 영역은 관리 상태, 무관심, 그리고 이상 상태의 세 영역으로 구성될 수 있다. 이 논문에서는 3개의 모수 영역이 있는 공정에 적용할 수 있는 두 가지 지수가중 이동평균(exponentially weighted moving average; EWMA) 관리도 절차를 제안하고, 제안된 절차의 성능을 Shewhart 관리도 및 누적합(cumulative sum; CUSUM) 관리도와 비교하여 그 효율을 평가하였다.