• Korea journal of population studies
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• v.12 no.1
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• pp.19-29
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• 1989

It is well known that vital statistics is of great importance as basic data for establishing various range of national policies. Especially, vital statistics is important among demographic information for monitoring and evaluating the population policy, for constructing life table, for making population projection, and for studying various aspects of the society. In principle, the production of vital statistics is based on the registration system. It is, however, still observed that there are some limitations in utilizing fully the registration system due to the inherent problems such as problems in its coverage, accuracies and timeliness. Thus, as an alternative, many countries conduct survey on vital statistics in order to supplement the registration system and obtain in-depth data. Korea is no exception in this aspect. The National Bureau of Statistics carries out the so-called Continuous Demographic Survey. This is a kind of multi-round retrospective survey, covering 32, 000 households and having reference period of one month. The survey has also characteristics of multi-subject sample. Thus, surveys on economic activity status of population, house-hold income & expenditure, and social indicators are together conducted with the same sample. It is, however, found that the survey itself tends to have some quality problems. Especially, the quality problems connected with field data collection are summarized as coverage error, non-response error and response error. Although it is inevitable not to be free from these errors, we should make all our efforts to reduce the errors. The probable schemes pointed out in this paper are as follows : 1) the strengthening formal quality control activities, 2) the review of the survey method, i. e., the combining interview method with mail-sending and mail-back method or pick-up method, 3) well documentation for various cases found in every stage of data collection, and 4) the strengthening the analytical activities. It is, also, emphasized that sincerity of planners and interviewers is the most important factor among other things.

• Journal of the Korean Data and Information Science Society
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• v.1
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• pp.59-65
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• 1990

The Edgeworth expansion, the Roy-Tiku method and the bootstrap method for approximating the distribution of the sample variance are compared through the Monte Carlo simulation study.

• The Journal of the Acoustical Society of Korea
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• v.16 no.6
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• pp.25-35
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• 1997

Most of speech analysis methods developed up to date are based on second order statistics, and one of the biggest drawback of these methods is that they show dramatical performance degradation in noisy environments. On the contrary, the methods using higher order statistics(HOS), which has the property of suppressing Gaussian noise, enable robust feature extraction in noisy environments. In this paper we propose a text-independent speaker identification system using higher order statistics and compare its performance with that using the conventional second-order-statistics-based method in both white and colored noise environments. The proposed speaker identification system is based on the vector quantization approach, and employs HOS-based voiced/unvoiced detector in order to extract feature parameters for voiced speech only, which has non-Gaussian distribution and is known to contain most of speaker-specific characteristics. Experimental results using 50 speaker's database show that higher-order-statistics-based method gives a better identificaiton performance than the conventional second-order-statistics-based method in noisy environments.

• Journal of Oriental Neuropsychiatry
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• v.18 no.3
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• pp.15-21
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• 2007

This study was done to review problems in terms of statistical description and statistical application and analysis. Methods; The authors reviewed 42 statistical clinical study papers excluding 12 Overview papers, 75 Descriptive papers, 48 Animal studies out of 177 papers in the Journal of Oriental Neuropsychiatry in the 5 years from 2002 to 2006. Results : 1) 3 papers(7.1%) had no description of statistical method, only P-values, 25 papaers(59.5%) had tables without description of statistical method, 1 paper (2.3%) had no description of statistical method in study method. 2) 10 papers(23.8%) contained problems in terms of statistical application and analysis. 6papers (6/23, 26.0%) for Student t-test, 2 papers(2/7 28.6%)for $X^2$- test, 1 paper(1/15 6.7%) for the analysis of variance, 1 paper(1/6 16.7%) for Pearson correlation contained statistical problems. Conclusion : It was suggested that consultation of investigators with statisticians and more extensive statistical refereeing, the form of the guidelines for description and application of statistics are needed.

• The Korean Journal of Applied Statistics
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• v.30 no.3
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• pp.345-362
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• 2017

Various data visualization methods are utilized to analyze a huge amount of data. Among various methods, a three-dimensional image requires the rotation of the image to show a stereo image on a two-dimensional screen. This study discusses two methods of batch method and real-time method, which make it possible to construct of stereo images to improve the restriction of the three-dimensional image display with virtual reality. This investigation can be useful to better explore a three-dimensional data structure.

• Journal of Periodontal and Implant Science
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• v.39 no.4
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• pp.399-405
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• 2009

Purpose: This article is purposed to present the correct statistic method by pointing out the statistical errors after analyzing the method of articles that were published in Korean Academy Journal of Periodontology and made statistic processes in them. Methods: 488 science papers which being put in Korean Academy Journal of Periodontology published from 2000 to 2006 was divided according to year. Results: In the 308 articles that applied statistic methods, 59 articles (50.0%), the largest portion of all, were included the case that applied incorrect parametric statistic method when needed to apply parametric statistics and 38 articles (32.2%) were included in the case that applied incorrect parametric statistic method when needed to apply non-parametric statistics. Conclusions: It is necessary to present the cases of inappropriate statistical methods in order to improve the quality of academic researches. Also, to apply adequate methods of statistics, it is suggested to report the articles periodically which are comparing and analyzing the statistical methods that are applied in the international articles in periodontal field.

• The Korean Journal of Applied Statistics
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• v.34 no.2
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• pp.127-139
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• 2021

Independent Component Analysis is a popular statistical method to separate independent signals from the mixed data, and Group Independent Component Analysis is an its multi-subject extension of Independent Component Analysis. It has been applied Functional Magnetic Resonance Imaging data and provides promising results. However, classical Group Independent Component Analysis works poorly when outliers exist on data which is frequently occurred in Magnetic Resonance Imaging scanning. In this study, we propose a robust version of the Group Independent Component Analysis based on ROBPCA. Through the numerical studies, we compare proposed method to the conventional method, and verify the robustness of the proposed method.

• Communications for Statistical Applications and Methods
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• v.14 no.2
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• pp.365-376
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• 2007

This research considers to propose the control charts using median for the location parameter. In order to decide the control limits, we apply several bootstrap methods through the approach obtaining the confidence interval except the standard bootstrap method. Then we illustrate our procedure using an example and compare the performance among the various bootstrap methods by obtaining the length between control limits through the simulation study. The standard bootstrap may be apt to yield shortest length while the bootstrap-t method, the longest one. Finally we comment briefly about some specific features as concluding remarks.

• Communications for Statistical Applications and Methods
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• v.25 no.1
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• pp.71-78
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• 2018

In this study, we consider the likelihood ratio test for the covariance matrix of the multivariate normal data. For this, we propose a method for obtaining null distributions of the likelihood ratio statistics by the Monte-Carlo approach when it is difficult to derive the exact null distributions theoretically. Then we compare the performance and precision of distributions obtained by the asymptotic normality and the Monte-Carlo method for the likelihood ratio test through a simulation study. Finally we discuss some interesting features related to the likelihood ratio test for the covariance matrix and the Monte-Carlo method for obtaining null distributions for the likelihood ratio statistics.

• Communications for Statistical Applications and Methods
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• v.10 no.2
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• pp.305-317
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• 2003

We suggest methods to measure the changes in $x^2$ statistic when a row is deleted from a two-way contingency table. The influence function is extended and the deletion method is applied. Two examples are presented and we compare the results obtained from the influence function method and the deletion method.