• Title/Summary/Keyword: Contingency table

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The Eccentric Properties of the Chi-Squared Test with Yates' Continuity Correction in Extremely Unbalanced 2×2 Contingency Table

  • Kang, Seung-Ho;Kwon, Tae-Hyuk
    • The Korean Journal of Applied Statistics
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    • v.23 no.4
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    • pp.777-781
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    • 2010
  • Yates' continuity correction of the chi-squared test for testing the homogeneity of two binomial proportions in $2{\times}2$ contingency tables is developed to lower the value of the test statistic slightly. The effect of continuity correction is expected to decrease as the sample size increases. However, in extremely unbalanced $2{\times}2$ contingency tables, we find some cases where the effect of continuity correction is eccentric and is larger than expected. In such cases, we conclude that the chi-squared test with continuity correction should not be employed as a test statistic in both asymptotic tests and exact tests.

MEASURE OF DEPARTURE FROM QUASI-SYMMETRY AND BRADLEY-TERRY MODELS FOR SQUARE CONTINGENCY TABLES WITH NOMINAL CATEGORIES

  • Kouji Tahata;Nobuko Miyamoto;Sadao Tomizawa
    • Journal of the Korean Statistical Society
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    • v.33 no.1
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    • pp.129-147
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    • 2004
  • For square contingency tables with nominal categories, this paper proposes a measure to represent the degree of departure from the quasi-symmetry (QS) model and the Bradley-Terry (BT) model. The measure proposed is expressed by using the Cressie and Read (1984)'s power-divergence or Patil and Taillie (1982)'s diversity index. The measure lies between 0 and 1, and it is useful for comparing the degree of departure from QS or BT in several tables.

Overload Alleviation Algorithm by the Bus Injection Power Control (모선주입전력 조정에 의한 과부하 해소 앨고리즘)

  • 박규홍;정재길;안민옥
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.39 no.2
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    • pp.111-118
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    • 1990
  • This paper presents a new algorithm of contingency analysis and countermeasure to alleviate the line overloads for electric power systems. In this algorithm, the inverse matrix of the new Jacobian matrix when a contingency occurs, in fastly calculated using the house-holder's Inverse Matrix Modification Lamma (IMML) with the original factor table. The generation outputs are firstly adjusted to alleviate all line overloads occurred by the contingency without tripping loads. If the generation adjustment is not enough anymore to alleviate line overloads, then the control of bus injection power is recommended to quickly alleviate remaining overloads with minimum amount of load tripping and generation read-justing at the termination busbars of the overload lines. The proposed algorithm has been validated in tests on the 6 busbar test system.

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Testing Independence in Contingency Tables with Clustered Data (집락자료의 분할표에서 독립성검정)

  • 정광모;이현영
    • The Korean Journal of Applied Statistics
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    • v.17 no.2
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    • pp.337-346
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    • 2004
  • The Pearson chi-square goodness-of-fit test and the likelihood ratio tests are usually used for testing independence in two-way contingency tables under random sampling. But both of these tests may provide false results for the contingency table with clustered observations. In this case we consider the generalized linear mixed model which includes random effects of clustering in addition to the fixed effects of covariates. Both the heterogeneity between clusters and the dependency within a cluster can be explained via generalized linear mixed model. In this paper we introduce several types of generalized linear mixed model for testing independence in contingency tables with clustered observations. We also discuss the fitting of these models through a real dataset.

Maximum Trimmed Likelihood Estimator for Categorical Data Analysis (범주형 자료분석을 위한 최대절사우도추정)

  • Choi, Hyun-Jip
    • Communications for Statistical Applications and Methods
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    • v.16 no.2
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    • pp.229-238
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    • 2009
  • We propose a simple algorithm for obtaining MTL(maximum trimmed likelihood) estimates. The algorithm finds the subset to use to obtain the global maximum in the series of eliminating process which depends on the likelihood of cells in a contingency table. To evaluate the performance of the algorithm for MTL estimators, we conducted simulation studies. The results showed that the algorithm is very competitive in terms of computational burdens required to get the same or the similar results in comparison with the complete enumeration.

Chi-Squared Test of Independence in Case that Two Marginal Distributions are Given Exactly (모집단 부분정보가 주어진 상황에서의 분할표 독립성 검정)

  • 이광진
    • The Korean Journal of Applied Statistics
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    • v.17 no.1
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    • pp.89-103
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    • 2004
  • If the given information is exact, though it is the little, we had better use it than not use in analysis. In this article, the problem of independence test in a contingency table is considered when two marginal distributions of a population are given exactly. For that case, a likelihood-ratio chi-squared test statistic and its Pearsonian type chi-squared test statistic are derived. By Monte Carlo Simulations the traditional chi-square tests and the derived tests are compared. And the related some testing problems are synthetically explained on a geometrical viewpoint.

Design of a Fast Algorithm for Computing Contingency Tables that are Used to Construct Epistasis Networks of SNPs (단일염기다형성 상위성 네트워크를 구성하기 위한 분할표를 생성하는 빠른 알고리즘의 설계)

  • Wang, Sehee;Wee, Kyubum
    • Proceedings of the Korean Society of Computer Information Conference
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    • 2016.07a
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    • pp.21-24
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    • 2016
  • 전장유전체 연관성 연구에서 상위성 탐색은 많은 단일염기다형성 수로 인해 계산이 어렵기 때문에 네트워크에서의 탐색을 이용한 방법이 사용되고 있다. 그러나 전장유전체 연관성 연구에서 단일염기다형성들의 상위성 네트워크의 구성 역시 큰 계산 비용을 필요로 한다. 본 논문에서는 단일염기다형성과 표현형의 상호정보량을 이용한 네트워크를 구성하는데 드는 시간을 줄이는 알고리즘을 제안한다. 또한 표본 크기별로 계산 시간을 실험해 보았으며, 기존의 방법과 비교해 실행 속도가 향상됨을 보였다.

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Small sample tests for two-way contingency tables (2원 분할표의 소표본 검증법)

  • 허명회
    • The Korean Journal of Applied Statistics
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    • v.10 no.2
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    • pp.339-352
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    • 1997
  • Chi-square test based on large sample theory is inappropriate for testing the row homogeneity in two-way contingency table with several sparse cells. For that case, exact testing methods has been developed in the literature and implemented in StatXact(1991). However, considerable computing time is inevitable for moderate size tables. So, Monte Carlo approximation is recommended frequently. In this study, we propose a simple algorithm for generating two-way random tables with fixed row and column margins for small sample chi-square test. Also, we develop “Turkey-type” method for multiple between-row comparisons.

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A Study on Contingency Analysis Criteria based on Historical Transmission System's Outage Data (송전망 고장확률(FOR) 크기에 따른 상정고장 적용 기준)

  • Cha, S.T.;Kim, T.K.;Kwak, B.M.;Jeon, D.H.;Lee, J.W.;Lee, B.S.;Lee, S.H.
    • Proceedings of the KIEE Conference
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    • 2005.07a
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    • pp.232-234
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    • 2005
  • This paper will produce a practical, accurate method for computing the equipment forced outages rate (FOR) based on 10 years of historical equipment outages data. Also, the location and weather conditions on outages are included. The computed FOR are ranked as 4 groups (presumably high, medium, low & very low) depending on the frequency (up to # times per year) and a consistent framework for transmission reliability performance table is developed based on these groupings. Our intent is to use this framework as guidelines for contingency analysis criteria in system planning / operation departments. The concepts are illustrated on the 2005 KEPCO power system.

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A Study on Cell Influences to Chi-square Statistic in Contingency Tables

  • Kim, Hong-Gie
    • Communications for Statistical Applications and Methods
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    • v.5 no.1
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    • pp.35-42
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    • 1998
  • Once a contingency table is constructed, the first interest will be the hypotheses of either homogeneity or independence depending on the sampling scheme. The most widely used test statistic in practice is the classical Pearson's $\chi^2$ statistic. When the null hypothesis is rejected, another natural interest becomes which cell contributed to the rejection of the null hypothesis more than others. For this purpose, so called cell $\chi^2$ components are investigated. In this paper, the influence function of a cell to the $\chi^2$ statistic is derived, which can be used for the same purpose. This function measures the effect of each cell to the $\chi$$^2$ statistic. A numerical example is given to demonstrate the role of the new function.

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