• Journal of the Korean Data and Information Science Society
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• 제25권6호
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• pp.1481-1489
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• 2014

한국 프로야구 총 관중수 예측에 대해 기존의 선행 연구에서는 주로 자기회귀누적이동평균 모형이 사용되고 있다. 본 논문에서는 공변량을 고려한 자기회귀누적이동평균 모형과 성장곡선 모형을 이용하여 프로야구 관중 수에 대한 예측 모형을 제시하고 기존의 선행 연구 모형과 비교하고자 한다. 공변량을 이용한 모형을 사용함으로써 기존의 선행 연구 모형보다 보다 개선된 예측력을 얻을 수 있었다. 이는 통계적 자료분석에서 한 가지 방법보다는 다양한 방법을 시도한 후 비교, 논의를 통하여 자료를 가장 잘 설명해 줄 수 있는 최적 방법을 찾아야 한다는 사실을 확인할 수 있다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5655-5661
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• 2015

Purpose: To assess the role of two adjuvant chemotherapy regimens, anthracycline-based and CMF on disease free survival and overall survival breast cancer patients by meta-analysis approach in Eastern Mediterranean and Asian countries to determine which is more effective and evaluate the appropriateness and efficiency of two different proposed statistical models. Materials and Methods: Survival curves were digitized and the survival proportions and times were extracted and modeled to appropriate covariates by two multivariate mixed effects models. Studies which reported disease free survival and overall survival curves for anthracycline-based or CMF as adjuvant chemotherapy that were published in English in the Eastern Mediterranean region and Asia were included in this systematic review. The two transformations of survival probabilities (Ln (-Ln(S)) and Ln(S/ (1-S))) as dependent variables were modeled by a multivariate mixed model to same covariates in order to have precise estimations with high power and appropriate interpretation of covariate effects. The analysis was carried out with SAS Proc MIXED and STATA software. Results: A total of 32 studies from the published literature were analysed, covering 4,092 patients who received anthracycline-based and 2,501 treated with CMF for the disease free survival and in order to analyze the overall survival, 13 studies reported the overall survival curves in which 2,050 cases were treated with anthracycline-based and 1,282 with CMF regimens. Conclusions: The findings illustrated that the model with dependent variable Ln (-Ln(S)) had more precise estimations of the covariate effects and showed significant difference between the effects of two adjuvant chemotherapy regimens. Anthracycline-based treatment gave better disease free survival and overall survival. As an IPD meta-analysis in the Italy the results of Angelo et al in 2011 also confirmed that anthracycline-based regimens were more effective for survival of breast cancer patients. The findings of Zare et al 2012 on disease free survival curves in Asia also provided similar evidence.

• 대한화학회지
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• 제46권4호
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• pp.377-384
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• 2002

본 연구에서는 학생들이 사전 성취 수준에 따른 협동적 컴퓨터 보조 수업의 쇼과를 개념 이해도, 개념 적용력, 학습 동기 측면에서 조사하였다. 서울시의 중학교 2개 학급을 대상으로 분자 운동 단원에 대해 5차시 동산 수업을 실시하였다. 수업 처치 전, 학습 동기 검사를 실시하여 공변인으로 사용하였다. 사전 학업 성취도 검사 점수는 개념 관련 변인의 공변인으로 사용하였다. 중간고사 과학 성적을 조사하여 구획변인으로 사용하였다. 수업처치 후 , 개념검사, 개념 적용력 검사, 학습 동기 검사를 실시하였다. 이원 공변량 분석 결과 개념 검사와 개념 적용력 검사 점수에서는 처치 집단과 통제 집단 사이에 유의미한 차이가 없었다. 그러나 학습 동기 검사에서는 처치 집단의 점수가 통제 집단에 비하여 유의미하게 높았다.

• International Journal of Human Ecology
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• 제8권1호
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• pp.9-18
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• 2007

This study focuses on the relationship between ethnic identity of Asian-Americans and their appreciation of their ethnic body features, based on reference group theory. A convenience sample of 60 male and 52 female students from various Asian ethnicities attending a mid-western university was used for the study. A 2 (gender) by 2 (ethnic identification) by 2 (socializing group) analysis of covariance (ANCOVA) on body image satisfaction as dependent variable and Body Mass Index score as a covariate was conducted. A significant main effect of ethnic identification was found, which indicates the more respondents identified with their ethnic group, the more likely they were to be satisfied with their appearance. The social group affiliation main effect was not significant. The impact of ethnic identification was significant only for those respondents who socialize more with Americans than with Asians. The results support the idea that one's ethnic group functions as a reference group, which influences body image appraisals.

• Journal of the Korean Data and Information Science Society
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• 제28권3호
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• pp.697-707
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• 2017

In this paper, we propose a modified GARCH(p, q)-X model which is obtained by adding the exogenous variables to the modified GARCH(p, q) process. Some limiting properties are shown under various stationary and nonstationary exogenous processes which are generated by another process independent of the noise process. The proposed model extends the GARCH(1, 1)-X model studied by Han (2015) to various GARCH(p, q)-type models such as GJR GARCH, asymptotic power GARCH and VGARCH combined with exogenous process. In comparison with GARCH(1, 1)-X, we expect that many stylized facts including long memory property of the financial time series can be explained effectively by modified GARCH(p, q) model combined with proper additional covariate.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2005년도 학술발표대회 논문집
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• pp.265-269
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• 2005

Cox's proportional hazards model (PHM) has been widely applied in the analysis of lifetime data, and it can be characterized by the baseline hazard function and covariates influencing systems' lifetime, where the covariates describe operating environments (e.g. temperature, pressure, humidity). In this article, we consider the constant baseline hazard function and a discrete random variable of a covariate. The estimation procedure is developed in a parametric framework when there are not only complete data but also incomplete one. The Expectation-Maximization (EM) algorithm is employed to handle the incomplete data problem. Simulation results are presented to illustrate the accuracy and some properties of the estimation results.

• 응용통계연구
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• 제34권3호
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• pp.411-425
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• 2021

가속화 실패시간모형은 로그 생존시간과 공변량간의 선형적 관계를 묘사해 준다. 가속화 실패시간모형에서 생존시간의 평균뿐만 아니라 변동성에도 영향을 미치는 공변량 효과를 추론하는 것은 흥미가 있다. 이를 위해 생존시간의 평균뿐만 아니라 분산을 모형화 하는 것이 필요하며, 이러한 모형을 평균-분산 가속화 실패시간모형이라 부른다. 본 논문에서는 벌점 가능도함수를 이용하여 평균-분산 가속화 실패시간모형에서 회귀모수에 대한 변수선택 절차를 제안한다. 여기서 벌점함수로서 LASSO, ALASSO, SCAD 그리고 HL (계층가능도)와 같은 네 가지 벌점함수를 연구한다. 제안된 변수선택 절차를 통해 중요한 공변량의 선택 뿐만 아니라 회귀모수의 추정을 동시에 제공할 수 있다. 제안된 방법의 성능은 모의실험을 통해 평가하고, 하나의 임상 예제자료를 통해 제안된 방법을 예증하고자 한다.

• Journal of the Korean Data and Information Science Society
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• 제24권6호
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• pp.1465-1475
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• 2013

The chi-square type test statistic is the most commonly used test in terms of measuring testing goodness-of-fit for multinomial logistic regression model, which has its grouped data (binomial data) and ungrouped (binary) data classified by a covariate pattern. Chi-square type statistic is not a satisfactory gauge, however, because the ungrouped Pearson chi-square statistic does not adhere well to the chi-square statistic and the ungrouped Pearson chi-square statistic is also not a satisfactory form of measurement in itself. Currently, goodness-of-fit in the ordinal setting is often assessed using the Pearson chi-square statistic and deviance tests. These tests involve creating a contingency table in which rows consist of all possible cross-classifications of the model covariates, and columns consist of the levels of the ordinal response. I examined goodness-of-fit tests for a proportional odds logistic regression model-the most commonly used regression model for an ordinal response variable. Using a simulation study, I investigated the distribution and power properties of this test and compared these with those of three other goodness-of-fit tests. The new test had lower power than the existing tests; however, it was able to detect a greater number of the different types of lack of fit considered in this study. I illustrated the ability of the tests to detect lack of fit using a study of aftercare decisions for psychiatrically hospitalized adolescents.

• 중환자간호학회지
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• 제13권3호
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• pp.41-50
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• 2020

Purpose : This descriptive research study aimed to identify the factors influencing nursing students' empathy and gender role identity and their effect on communication competence. Methods : Participants were 183 senior nursing students who had completed a clinical practice and simulation-based practical training course. Using the IBM SPSS/WIN 21.0 program, general characteristics were analyzed using descriptive statistics, independent variables were compared with t-tests and 𝑥² tests, and influencing factors on each variable and communication underwent multiple linear regression analysis. Results : Communication competence showed significant correlations with empathy (r=.40, p<.001), gender role identity (r=.53, p<.001), major satisfaction (r=.18, p=.013), and peer relationships (r=.24, p<.001). When gender was entered as a covariate, empathy (t=4.41, p<.001) and gender role identity (t=6.97, p<.001) were identified as predictors affecting communication competence with 36% explanation power (R²=.36, p<.001). Conclusion : The findings of this study suggest that course subjects considering the gender identities of students should be developed through various programs to establish students' identity as nurses and improve their empathy and communication.

• Communications for Statistical Applications and Methods
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• 제23권6호
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• pp.543-553
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• 2016

The validity of statistical inference depends on proper randomization methods. However, even with proper randomization, we can have imbalanced with respect to important characteristics. In this paper, we introduce a method based on ranked auxiliary variables for treatment allocation in crossover designs using Latin squares models. We evaluate the improvement of the efficiency in treatment comparisons using the proposed method. Our simulation study reveals that our proposed method provides a more powerful test compared to simple randomization with the same sample size. The proposed method is illustrated by conducting an experiment to compare two different concentrations of titanium dioxide nanofiber (TDNF) on rats for the purpose of comparing weight gain.