• Title/Summary/Keyword: 월콕슨 방법

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Efficient Edge Detection in Noisy Images using Robust Rank-Order Test (잡음영상에서 로버스트 순위-순서 검정을 이용한 효과적인 에지검출)

  • Lim, Dong-Hoon
    • The Korean Journal of Applied Statistics
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    • v.20 no.1
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    • pp.147-157
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    • 2007
  • Edge detection has been widely used in computer vision and image processing. We describe a new edge detector based on the robust rank-order test which is a useful alternative to Wilcoxon test. Our method is based on detecting pixel intensity changes between two neighborhoods with a $r{\times}r$ window using an edge-height model to perform effectively on noisy images. Some experiments of our robust rank-order detector with several existing edge detectors are carried out on both synthetic images and real images with and without noise.

An Empirical Measurement Way of Efficiency Prediction for Korean Seaports : SBM and Wilcoxson Signed-Rank Test Approach (항만의 효율성을 예측하기 위한 실증적 측정방법 - SBM과 윌콕슨부호순위검정접근 -)

  • Park, No-Gyeong
    • Journal of Korea Port Economic Association
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    • v.24 no.4
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    • pp.313-327
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    • 2008
  • The purpose of this paper is to show the empirical measurement way for predicting the seaport efficiency by using SBM with Wilcoxson signed-rank test under CRS(constant returns to scale) condition for 20 Korean ports during 1994-2003 for 2 inputs(birthing capacity, cargo handling capacity) and 3 outputs(Export and Import Quantity, Number of Ship Calls, Port Revenue). The main empirical results of this paper are as follows. First, forecasting data have well reflected the real data according to the Wilcoxon signed rank test, because p values have exceeded the 0.05 significance level. Second, SBM has shown the effectiveness for predicting the ports efficiency even though the predicting powers are different according to the levels of p values. The policy implication to the Korean seaports and planner is that Korean seaports should introduce the new methods like SBM method with Wilcoxon signed rank test for predicting the port performance and enhancing the efficiency.

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Determination of Sample Sizes of Bivariate Efficacy and Safety Outcomes (이변량 효능과 안전성 이항변수의 표본수 결정방법)

  • Lee, Hyun-Hak;Song, Hae-Hiang
    • The Korean Journal of Applied Statistics
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    • v.22 no.2
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    • pp.341-353
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    • 2009
  • We consider sample-size determination problem motivated by comparative clinical trials where patient outcomes are characterized by a bivariate outcome of efficacy and safety. Thall and Cheng (1999) presented a sample size methodology for the case of bivariate binary outcomes. We propose a bivariate Wilcoxon-Mann-Whitney(WMW) statistics for sample-size determination for binary outcomes, and this nonparametric method can be equally used to determine sample sizes of ordinal outcomes. The two methods of sample size determination rely on the same testing strategy for the target parameters but differs in the test statistics, an asymptotic bivariate normal statistic of the transformed proportions in Thall and Cheng (1999) and nonparametric bivariate WMW statistic in the other method. Sample sizes are calculated for the two experimental oncology trials, described in Thall and Cheng (1999), and for the first trial example the sample sizes of a bivariate WMW statistic are smaller than those of Thall and Cheng (1999), while for the second trial example the reverse is true.