• Title, Summary, Keyword: 백분위수

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Percetiles for the distributions belonging to the natural exponential families having power variance functions (파워(>2)분산함수를 가진 자연지수계열군에 속하는 분포들의 백분위수)

  • 서의훈
    • The Korean Journal of Applied Statistics
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    • v.8 no.1
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    • pp.133-149
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    • 1995
  • Since probability density functions for the distributions belonging to the natural exponential families having power(>2) variance functions are expressed as infinite series, it is very difficult to deal with the distributins in spite of their usefulness. Therefore, tables for the percentiles of the distributions are obtained, and approximate percentiles are also obtained in this thesis. It is shown that the approximate percentiles can replace exact percentlies well for some distributions.

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Determining proper threshold levels for hydrological drought analysis based on independent tests (수문학적 가뭄 특성 분석을 위한 독립성 검정 기반의 적정 임계수준 결정)

  • Kim, Tae-Woong;Park, Ji Yeon;Shin, Ji Yae
    • Journal of Korea Water Resources Association
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    • v.53 no.3
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    • pp.193-200
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    • 2020
  • Hydrological drought is directly associated with lack of available water in rivers, reservoirs, and groundwater. It is important to analyze hydrological drought for efficient water resource management because most of rainfall is concentrated in wet seasons and water supply is highly dependent on dams and reservoirs in South Korea. Generally, a threshold level method is useful for defining hydrological droughts. However, this method causes interdependent problems between drought events which result in skewed results in further statistical analysis. Therefore, it is necessary to determine a proper threshold level to represent regional drought characteristics. In this study, applying 50~99 percentiles of daily flow-duration curve, hydrological drought events were extracted, and independence tests were conducted for 12 watersheds. The Poisson independence test showed that 87~99 percentiles were available for most stations except for Yeoju and Pyeongtaek. The generalized Pareto independence test showed that 80~90 percentiles were the most common. Mean excess plot showed that 80 ~ 90 percentiles were the most common. Therefore, the common ranges of the three independent tests were determined for each station and proper threshold levels were recommended for large river basins; 70~76 percentiles for the Han River basin, 87~91 percentiles for the Nakdong River basin, 86~98 percentiles for the Geum River basin, and 85~87 percentiles for the Youngsan and Seomjin River basin.

Sequential Percentile Estimation for Sequential Steady-State Simulation (순차적 시뮬레이션을 위한 순차적인 Percentile 추정에 관한 연구)

  • Lee, Jong-Suk;Jeong, Hae-Duck
    • The KIPS Transactions:PartD
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    • v.10D no.6
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    • pp.1025-1032
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    • 2003
  • Percentiles are convenient measures of the entire range of values of simulation outputs. However, unlike means and standard deviations, the observations have to be stored since calculation of percentiles requires several passes through the data. Thus, percentile (PE) requires a large amount of computer storage and computation time. The best possible computation time to sort n observations is (O($nlog_{2}n$)), and memory proportional to n is required to store sorted values in order to find a given order statistic. Several approaches for extimating percentiles in RS(regenerative simulation) and non-RS, which can avoid difficulties of PE, have been proposed in [11, 12, 21]. In this paper, we implemented these three approaches known as : leanear PE, batching PE, spectral $P^2$ PE in the context of sequential steady-state simulation. Numerical results of coverage analysis of these PE approachs are present.

Correlation between Body Fat Percent Estimated by Bioelectrical Impedance Analysis and Other Variable Methods (생체전기 저항법에 의한 체지방율과 다른 계측치간의 상관성 연구)

  • Yom, Hye Won;Kim, Su Jung;Whang, Il Tae;Hong, Young Mi
    • Clinical and Experimental Pediatrics
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    • v.46 no.8
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    • pp.751-757
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    • 2003
  • Purpose : Obesity is a significant health problem with medical and psychological consequences for children and adolescents. The purpose of this study was to assess the correlation between body fat percent using bioelectrical impedance(BI) and other variable methods. Methods : We measured height, weight, body mass index(BMI) and body fat percent by skinfold thickness(ST) and BI in 1,035(496 male; 539 female) children from seven to 18 years of age. The correlation coefficients between BI and each of the other different methods were obtained. The sensitivity and specificity to predict obesity by these several methods were studied. Results : Fat percent estimated by BI analysis and BMI showed a strong correlation(r=0.749). Fat percent estimated by BI analysis and ST showed a very strong correlation(r=0.835). At the 95th percentile cut-off point for BI, ST showed a sensitivity of 57.7%, and a specificity of 97.6% for estimating body fat. At the 95th percentile cut-off point for BI, BMI showed a sensitivity of 84.9%, and a specificity of 99.3% for estimating body fat. Conclusion : The fat percent estimated by BI analysis correlated strongly with ST or BMI. BI analysis is an objective and accurate method for estimating body fat in childhood obesity.

Preliminary analysis of metabolic syndrome components in Korean adolescents by using Korean national health and nutrition examination Survey pooling data (1998, 2001, and 2005) (한국국민건강영양조사 병합자료(1998년, 2001년, 2005년)를 이용한 소아청소년에서의 대사증후군 진단 요인의 기초 분석)

  • Huh, Kyoung;Park, Mi Jung
    • Clinical and Experimental Pediatrics
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    • v.51 no.12
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    • pp.1300-1309
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    • 2008
  • Purpose :This study aimed to estimate age- and gender-specific cut points for metabolic syndrome (MS) components, including body mass index (BMI), blood pressure (BP), triglycerides, high-density lipoprotein (HDL) cholesterol, and glucose. Methods :Data from the 1998, 2001, and 2005 Korean NHANES (National Health and Nutrition Examination Survey) were analyzed (n=4164; 2,139 boys and 2,025 girls, aged 10-19 years). Height, weight, waist circumference (WC), BP, triglycerides, HDL cholesterol, and fasting glucose were measured. Results :BMI over $25kg/m^2$ represents the $85^{th}P$ (percentile) in 17-year-old boys and the $90^{th}P$ in 17-year-old girls. A level of WC higher than that of the cutoff points of Asian adults was found in the $90^{th}P$ of 17-year-old boys and girls. The $90^{th}P$ of boys aged 15 years old and the $95^{th}P$ of 13-year-old were included in the range of systolic BP over 130 mm Hg. Over the $75^{th}P$ of the group showed triglycerides greater than 110 mg/dL, (criterion of MS presented by NCEP-ATP III) and the $90^{th}P$ of the group showed triglycerides greater than 150 mg/dL by IDF. An HDL cholesterol level of 40 mg/dL represents the $25^{th}P$ in boys and the $10^{th}P$ in girls. A glucose level greater than 110 mg/dL represents the $95^{th}P$ and greater than 100 mg/dL represents the $90^{th}P$. Conclusion :Values of the $90^{th}P$ of MS components in late adolescent boys (WC, BP, and triglycerides) and girls (WC and triglycerides) were very high and in close proximity to the diagnostic criteria of adult MS.

Comparison of Functions for Filtering Time Course Gene Expression Data with Flat Patterns (무 변화 패턴을 갖는 시간경로 유전자발현자료를 제거하기 위한 함수들의 비교)

  • Kim, Kyung-Sook;Oh, Mi-Ra;Baek, Jang-Sun;Son, Young-Sook
    • The Korean Journal of Applied Statistics
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    • v.20 no.2
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    • pp.409-422
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    • 2007
  • Filtering genes that do not appear to contribute to regulation prior to the statistical analysis of time course gene expression data can reduce the dimensions of data and the possibility of misinterpretation due to noise or lack of variation. In this paper, we compare six different functions for filtering genes with flat pattern under the percentile criterion on an observed sample and that on a bootstrap sample. The result of applying to the yeast cell cycle data shows that the variance function is most similar in both samples.

Comparison of Methods for the Analysis Percentile of Seismic Hazards (지진재해도의 백분위수 분석 방법 비교)

  • Rhee, Hyun-Me;Seo, Jung-Moon;Kim, Min-Kyu;Choi, In-Kil
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.2
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    • pp.43-51
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    • 2011
  • Probabilistic seismic hazard analysis (PSHA), which can effectively apply inevitable uncertainties in seismic data, considers a number of seismotectonic models and attenuation equations. The calculated hazard by PSHA is generally a value dependent on peak ground acceleration (PGA) and expresses the value as an annual exceedance probability. To represent the uncertainty range of a hazard which has occurred using various seismic data, a hazard curve figure shows both a mean curve and percentile curves (15, 50, and 85). The percentile performs an important role in that it indicates the uncertainty range of the calculated hazard, could be calculated using various methods by the relation of the weight and hazard. This study using the weight accumulation method, the weighted hazard method, the maximum likelihood method, and the moment method, has calculated the percentile of the computed hazard by PSHA on the Shinuljin 1, 2 site. The calculated percentile using the weight accumulation method, the weighted hazard method, and the maximum likelihood method, have similar trends and represent the range of all computed hazards by PSHA. The calculated percentile using the moment method effectively showed the range of hazards at the source which includes a site. This study suggests the moment method as effective percentile calculation method considering the almost same mean hazard for the seismotectonic model and a source which includes a site.

The Study for NHPP Software Reliability Growth Model of Percentile Change-point (백분위수 변화점을 고려한 NHPP 소프트웨어 신뢰성장모형에 관한 연구)

  • Kim, Hee-Cheul;Shin, Hyun-Cheul
    • Convergence Security Journal
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    • v.8 no.4
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    • pp.115-120
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    • 2008
  • Accurate predictions of software release times, and estimation of the reliability and availability of a software product require quantification of a critical element of the software testing process: Change-point problem. In this paper, exponential (Goel-Okumoto) model was reviewed, proposes the percentile change-point problem, which maked out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE statistics, for the sake of efficient model, was employed. Using NTDS data, The numerical example of percentilechange-point problemi s presented.

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Use of Non-Parametric Statistical Method in Identifying Repetitive High Dose Jobs in a Nuclear Power Plant (비모수통계방법을 이용한 원자력발전소 작업자 반복성 고피폭작업 도출)

  • Young-Ho Cho;Young-Hoi Herr
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.2 no.1
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    • pp.41-51
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    • 2004
  • The cost-effective reduction of occupational radiation dose (ORD) at a nuclear power plant could not be achieved without going through an extensive analysis of accumulated ORD data of existing plants. Through the data analysis, it is required to identify what are the jobs of repetitive high ORD at the nuclear power plant. In this study, Percentile Rank Sum Method (PRSM) is proposed to identify repetitive high ORD jobs, which is based on non-parametric statistical theory. As a case study, the method is applied to ORD data of maintenance and repair jobs at Kori units 3 and 4 that are pressurized water reactors with 950 MWe capacity and have been operated since 1986 and 1987, respectively in Korea. The results was verified and validated, and PRSM has been demonstrated to be an efficient method of analyzing the data.

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Normative blood pressure references for Korean children and adolescents (한국 소아 청소년 정상 혈압 참고치)

  • Lee, Chong Guk;Moon, Jin Soo;Choi, Joong-Myung;Nam, Chung Mo;Lee, Soon Young;Oh, Kyungwon;Kim, Young Taek
    • Clinical and Experimental Pediatrics
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    • v.51 no.1
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    • pp.33-41
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    • 2008
  • Purpose : It is now understood that blood pressure (BP) measurement in the routine pediatric examination is very important because of the relevance of childhood BP to pediatric health care and the development of adult essential hypertension. There hasn't been a reference table of BP for Korean children and adolescents up to now. This study was to make normative BP references and to provide criteria of hypertension for Korean children and adolescents. Methods : BP measurements were done on 57,433 Koean children and adolescents (male: 29,443, female: 27,990), aged 7 to 20 years, in 2005. Heights and weights were measured simultaneously. Oscillometric devices, Dinamap Procare 200 (GE Inc., Milwaukee, Wi, USA), were used for the measurements. BPs were measured 2 times and mean levels were gathered for the analysis. Outliers of 2,373 subjects with overweight per height, over +3SD, were excluded for the analysis. For the BP centiles adjusted by sex, age and height, fixed modified LMS method which was adopted from the mixed effect model of 2004 Task Force in NHLBI (USA) was used. Results : Normative BP tables for Korean children and adolescents adjusted for height percentiles (5th, 10th, 25th, 50th, 75th, 90th, 95th), gender (male, female) and age(7 to 18 years) were completed. Height centiles of Korean children and adolescents are available from Korean Center for Disease Control and Prevention homepage, http://www.cdc.go.kr/webcdc/. Criteria of hypertension (95th, 99th percentile) and normal range of BP (50th, 90th) adjusted for height percentiles, age and gender were made. Conclusion : This is the first study to make normative BP tables and define hypertension for the Korean children and adolescents. Reliability and accuracy of Dinamap Procare 200 oscillometer for BP measurements remains debatable.