• Communications for Statistical Applications and Methods
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• v.24 no.3
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• pp.255-269
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• 2017

This article explores the analysis of longitudinal surveys in which same units are investigated on several occasions. Multivariate exponential ratio type estimator has been proposed for the estimation of the finite population median at the current occasion in two occasion longitudinal surveys. Information on several additional auxiliary variables, which are stable over time and readily available on both the occasions, has been utilized. Properties of the proposed multivariate estimator, including the optimum replacement strategy, are presented. The proposed multivariate estimator is compared with the sample median estimator when there is no matching from a previous occasion and with the exponential ratio type estimator in successive sampling when information is available on only one additional auxiliary variable. The merits of the proposed estimator are justified by empirical interpretations and validated by a simulation study with the help of some natural populations.

• Communications for Statistical Applications and Methods
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• v.21 no.5
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• pp.363-386
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• 2014

This paper has improved several ratio type estimators of the population median including their generalization in the presence of three known quartiles of an auxiliary variable. The properties of the improved estimators are discussed and applied. Both the empirical and simulation studies confirm that our new estimators perform efficiently.

• Communications for Statistical Applications and Methods
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• v.11 no.3
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• pp.513-518
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• 2004

The well-known mode-mean-median inequality for the unimodal population distribution does not always hold for the frequency distribution. But many elementary statistics text books just mention that the relative location of the mean and median can be used to determine whether a distribution is positively or negatively skewed. In this paper we introduce the method generating data that is positively skewed but mean

• Journal of the Korean Statistical Society
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• v.35 no.3
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• pp.331-341
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• 2006

An approximate distribution of the plug-in estimator of the squared coefficient of variation ($CV^2$) is derived by using Edgeworth expansions under general population models. Also bias of the estimator is investigated for several important distributions. Under the normal distribution, we proposed the new estimator for $CV^2$ based on median of the sampling distribution of plug-in estimator.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.973-980
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• 2004

Phase I clinical trials are often pharmacologically oriented and usually attempt to find the best dose of drug to employ. However, other purposes like determination of sizes and types of side effects and toxicity and organ system involved are equally important. Estimation of treatment effects or side effects is usually ignored since it is usually based on too small sample, even though Phase II clinical trials would be designed based on the Phase I studies. Statistical methods for constructing the approximate confidence interval for population median in case of small sample are considered and an improved method is proposed. The proposed estimator is compared with current methods through simulation studies.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.447-456
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• 2000

In this paper, we considered three methods for outlier identification sample surveys. First, we studied method of handling and adjusting outliers in normal population. Second, we studied existing methods using mean, maximum and minimum and proposed a test using of median which well reflects characteristic of data regardless of sampling distribution. Finally, we showed our test using median works better than Dixon and mean test through simulation.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.1
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• pp.131-133
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• 2012

Background: We aimed to investigate the relationship between blood groups and pancreatic cancer in a Turkish population in Western Blacksea region. Methods: This is a retrospective study. Zonguldak Karaelmas University outpatient oncology clinic records were screened for the period between 2004 and 2011. Results: The median age of patients were 56 (${\pm}16$) and 132 of 633 study population had pancreatic cancer. Pancreatic cancer patients had significantly higher rates of blood group A compared to controls (OR 1.8, 95%CI, p 0.005). Rates of blood group AB was significantly lower than the control group (OR 0.37, 95% CI, p 0.04). The median survival (IR) time in subjects having the blood groups A, B, AB and O were 7.0 (1-28), 7.0 (2-38), 10 (2-36) and 9.0 (2-48) months respectively; the blood group 0 had significantly higher overall survival (OS) compared to the non-0 groups (p 0.04). Conclusions: Pancreatic cancer patients had more common blood group A in our population. Moreover, blood group AB appeared to be a protective factor against pancreatic cancer in our population. Blood group 0 had a significantly longer survival compared to non-0, regardless of prognostic factors.

• Journal of the Korean Statistical Society
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• v.32 no.3
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• pp.299-309
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• 2003

Let ${\pi}_1,...,{\pi}_{k}$k($\geq$2) independent logistic populations such that the cumulative distribution function (cdf) of an observation from the population ${\pi}_{i}$ is $$F_{i}\;=\; {\frac{1}{1+exp{-\pi(x-{\mu}_{i})/(\sigma\sqrt{3})}}},\;$\mid$x$\mid$<\;{\infty}$$ where ${\mu}_{i}(-{\infty}\; < \; {\mu}_{i}\; <\; {\infty}$ is unknown location mean and ${\delta}^2$ is known variance, i ＝ 1,..., $textsc{k}$. Let ${\mu}_{[k]}$ be the largest of all ${\mu}$'s and the population ${\pi}_{i}$ is defined to be 'good' if ${\mu}_{i}\;{\geq}\;{\mu}_{[k]}\;-\;{\delta}_1$, where ${\delta}_1\;>\;0$, i = 1,...,$textsc{k}$. A selection procedure based on sample median is proposed to select a subset of $textsc{k}$ logistic populations which includes all the good populations with probability at least $P^{*}$(a preassigned value). Simultaneous confidence intervals for the differences of location parameters, which can be derived with the help of proposed procedures, are discussed. If a population with location parameter ${\mu}_{i}\;<\;{\mu}_{[k]}\;-\;{\delta}_2({\delta}_2\;>{\delta}_1)$, i ＝ 1,...,$textsc{k}$ is considered 'bad', a selection procedure is proposed so that the probability of either selecting a bad population or omitting a good population is at most 1­ $P^{*}$.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.549-562
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• 2000

Default Bayes factors are computed to test the equality of one Poisson population mean and the equality of two independent Possion population means. As default priors are assumed Jeffreys priors, noninformative improper priors, and default Bayes factors such as three intrinsic Bayes factors of Berger and Pericchi(1996, 1998), the arithmetic, the median, and the geometric intrinsic Bayes factor, and the factional Bayes factor of O'Hagan(1995) are computed. The testing results by each default Bayes factor are compared with those by the classical method in the simulation study.

• Korean Journal of Community Nutrition
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• v.20 no.6
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• pp.423-432
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• 2015

Objectives: In Korea, the percentage of elderly is increasing at an unprecedented rate, and is expected to account for 40% of the population by 2060. This massive demographic change stresses the importance of research on aging as it is necessary to improve the quality of life (QoL) of this population. This study aimed to examine the health-related quality of life (HRQoL) of the rural elderly and to clarify its association with the nutrient adequacy ratio (NAR). Methods: A cross-sectional study was performed in S-gun, Chonbuk, a critical agricultural area. The elderly people without abnormal physical functioning composed our study population and the data were collected by personal visits to 336 elderly people aged over 65 years (110 males and 226 females). Subjects were interviewed with questionnaires pertaining to general characteristics and EuroQol (EQ-5D). Nutrient intakes were assessed two days by 24-hours recall method. Subjects were defined as high QOL group if EQ-5D index with Nam's model was above the median. Results: Generally, EQ-5D index was lower in women than in man, and lower in older subjects than in younger subjects. The percentages of people below the median were 42% (low QoL group) and 58% (high QoL group) were found to be the above the median. The high QoL group had higher NAR, especially for vitamin C, vitamin B1, vitamin B2 and folate. All dimensions in the EQ-5D were affected by NAR of some nutrients and especially anxiety/depression dimension was significantly correlated with NAR of 5 nutrients (protein, calcium, iron, vitamin C and vitamin B1) and EQ-5D scores. Conclusions: HRQol was significantly reduced in elderly with increasing age and this was more pronounced in women than in man. The NAR of some nutrients were associated with the EQ-5D index, especially anxiety/depression dimension, among rural elderly.