• Journal of the Korean Statistical Society
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• v.26 no.2
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• pp.223-229
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• 1997

It is demonstrated that many standard nonparametric test such as the Mann-Whitney-Wilcoxon test, the Fisher-Yates test, the Savage test and the median test are admissible for a two-sample nonparametric testing problem. The admissibility of the Kruskal-Wallis test is demonstrated for a nonparametric one-way layout testing problem.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1499-1506
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• 2014

Random walk is used for describing random phenomenon in various areas but tests for random walk developed so far are known to suffer from size distortion and low power. Kim et al. (2014) proposed a sign test for unit root (${\rho}=1$) hypothesis based on slopes. This article proposes a Wilcoxon signed rank test based on slopes for unit root hypothesis, and compares it with the augmented Dickey-Fuller test and the sign test by a simulation study. Our results confirm that the nonparametric tests are better than ADF test for small samples like n = 30. The results also show that the sign test is better than the Wilcoxon signed rank test and that for 0 < ${\rho}$ < 1 (-1 < ${\rho}$ < 0), the nonparametric tests suffer from power loss (improvement) as normal error changes to double exponential error.

• The Korean Journal of Applied Statistics
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• v.21 no.6
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• pp.933-945
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• 2008

The genetic association test on age of onset trait aims to detect the putative gene by means of linear rank tests for a significant trend of onset distributions with genotypes. However, due to the selective sampling of recruiting subjects with ages less than a pre-specified limit, the genotype groups are subject to substantially different censored distributions and thus this is one reason for the low efficiencies in the linear rank tests. In testing the equality of two survival distributions, log-rank statistic is preferred to the Wilcoxon statistic, when censored observations are nonignorable. Therefore, for more then two groups, we propose a generalized log-rank test for trend as a genetic association test. Monte Carlo studies are conducted to investigate the performances of the test statistics examined in this paper.

• Journal of the Korean Statistical Society
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• v.26 no.2
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• pp.211-222
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• 1997

We briefly review three Raleigh type location tests based on direction vectors, which have been shown to be efficient when the distribution is unknown, skewed, or heavy-tailed. Then we calculate their test breakdown points and discuss the robustness of Randles multivariate sign test for one-sample.

• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.573-581
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• 2015

We study problems of sample size determination for one-sample location tests. A simulation study shows that sample size calculations based on approximated distribution do not achieve the nominal level of power. We investigate sample size determinations based on exact distribution and with a power that attains the nominal level.

• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.1021-1024
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• 2000

In this paper we describe a nonparametric Wilcoxon test and a parametric Z test based on statistical hypothesis testing for the detection of edges. We use the threshold determined by specifying significance level $\alpha$, while Bovik, Huang and Munson[4] consider the range of possible values of test statistics for the threshold. From the experimental results of edge detection, the Z method performs sensitively to the noisy image, while the Wilcoxon method is robust over both noisy nd noise-free images. Comparison with our statistical tests and Sobel operator shows that our tests perform more effectively in both noisy and noise-free images.

• Journal of the Korean Mathematical Society
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• v.14 no.2
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• pp.223-228
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• 1978

• The Korean Journal of Applied Statistics
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• v.19 no.3
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• pp.565-578
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• 2006

Repeated measurement data between two group is often used in the field of medicine study. In this paper, we suggest a method for comparison of the trend between two groups based on repeated measurement data. First, we estimate regression coefficient of linear regression model from each subject and generate samples using the regression coefficient estimated previous. And then, we test the difference between two groups by unpaired t-test, Wilcoxon rank sum test and placement test using generated samples. Monte Carlo Simulation is adapted to examine the power and experimental significance levels of several methods in various combinations.

• Proceedings of the Safety Management and Science Conference
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• 2008.04a
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• pp.451-460
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• 2008

This paper reviews nonparametric statistics by Neyman-Pearson test and Fisher test. Nonparametric statistics deal with the small sample with distribution-free assumption in multi-product and small-volume production. Two tests for various nonparametric statistic methods such as sign test, Wilcoxon test, Mann-Whitney test, Kruskal-Wallis test, Mood test, Friedman test and run test are also presented with the steps for testing hypotheses and test of significance.

• Journal of Korean Academy of Nursing
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• v.41 no.2
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• pp.175-181
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• 2011

Purpose: This study was conducted to identify endotracheal colonization and the incidence of ventilator-associated pneumonia related to the type of endotracheal suction system. Methods: The participants in this study were ICU patients hospitalized between October 2009 to March 2010 who used ventilators for over 48 hr with closed (CSS, n=30) or open (OSS, n=32) suction systems. To standardize the pre-intervention suction system, a suctioning protocol was taught to the ICU nurses. Collected data were analyzed using ${\chi}^2$-test, Fisher's exact test, Wilcoxon rank sums test, Wilcoxon test, Log-rank test and Poisson regression. Results: Endotracheal colonization was higher in OSS than CSS from day 1 to day 8 while using a ventilator and there was a significant difference between the two groups. The CSS reached 50% of endotracheal colonization by the 4th day, whereas for the OSS, it was the 2nd day (p=.04). The incidence of ventilator-associated pneumonia showed no significant difference. Conclusion: For patients with a high risk of pneumonia, CSS must be used to lower endotracheal colonization.