• Communications for Statistical Applications and Methods
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• 제23권1호
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• pp.1-20
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• 2016

Causal inference methodologies have been developed for the past decade to estimate the unconfounded effect of an exposure under several key assumptions. These assumptions include, but are not limited to, the stable unit treatment value assumption, the strong ignorability of treatment assignment assumption, and the assumption that propensity scores be bounded away from zero and one (the positivity assumption). Of these assumptions, the first two have received much attention in the literature. Yet the positivity assumption has been recently discussed in only a few papers. Propensity scores of zero or one are indicative of deterministic exposure so that causal effects cannot be defined for these subjects. Therefore, these subjects need to be removed because no comparable comparison groups can be found for such subjects. In this paper, using currently available causal inference methods, we evaluate the effect of arbitrary cutoffs in the distribution of propensity scores and the impact of those decisions on bias and efficiency. We propose a tree-based method that performs well in terms of bias reduction when the definition of positivity is based on a single confounder. This tree-based method can be easily implemented using the statistical software program, R. R code for the studies is available online.

• Journal of the Korean Data and Information Science Society
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• 제27권1호
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• pp.91-100
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• 2016

성향점수 매칭이란 선택편의가 존재 할 수 있는 두 집단의 데이터를 성향 점수로 매칭하여 비슷한 성향을 갖는 데이터를 추출하는 방법이다. 본 논문은 그 중 하나인 퍼지 매칭 방법을 제시하였다. 성향 점수를 만들기 위해 통제변수를 선정하는 방법과 로지스틱 회귀분석을 통하여 성향 점수를 구하는 방법을 제시하였으며, 이 점수로 퍼지 매칭을 통해 성향이 비슷한 실험 집단과 통제 집단을 추출할 수 있었다. 본 논문에서는 허용오차 범위를 달리하여 분포도와 표준화 차이를 통해 두 집단이 동일한 집단임을 증명했으며, 허용오차 범위 점수가 작아질수록 선택되어 지는 케이스 수도 작아지는 것을 확인 할 수 있었다.

• 한국조사연구학회지:조사연구
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• 제10권1호
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• pp.169-186
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• 2009

본 연구는 사회조사에서 무응답으로 인한 편향을 축소하는 방안으로 성향점수를 이용하는 방법과 사례를 설명하기 위해서 성향점수 방법의 이론적인 개념과 배경을 정리하였다. 또한 성향점수 방법을 처음으로 적용한 역학적인 관찰연구에서 성향점수 모형의 정의와 이론적 배경을 살펴보았고 추정에서 편향의 축소방법으로 이용되는 가지 성향점수 방법을 정리하였다. 성향점수로 짝짓기는 통제그룹의 데이터가 상대적으로 많을 경우에 이용되고 부차분류법은 통제그룹의 모든 데이터를 이용할 수 있으며 회귀모형을 이용한 보정은 다중공변량에서도 사용할 수 있을 뿐만 아니라 각 관찰단위에 성향점수 값을 산출하여 사용할 수 있는 특징이 있다. 그리고 사회여론조사에서 항목무응답으로 인한 편향을 축소하는 데 성향점수 가중법을 적용하는 절차를 제안하고 기존의 데이터를 이용하여 실제 적용에 대한 가능성을 검토하였다.

• 가족자원경영과 정책
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• 제8권3호
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• pp.47-64
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• 2004

This study compared full-time housewives' propensity for TV home shopping addiction by different socioeconomic, psychological, and purchase-related characteristics. And it identified the factors that influenced full-time housewives' TV home shopping addiction. The data were obtained from a questionnaire completed by full-time housewives (n=225) lived in Seoul and were analyzed by t-tests, ANOVA, and a multiple regression analysis. The findings of this study were as follows: First, full-time housewives' propensity for TV home shopping addiction was higher in the relatively old aged group. Those who graduated from graduate schools had lower scores in the scale of TV shopping addiction. Also, middle income group showed higher propensity for addictive buying. Second, the propensity for TV home shopping addiction was higher among those who had low self-esteem, who had higher level of empty self Also, those who had experienced material compensations as a child showed higher propensity for addictive purchase. Third, the propensity for addictive buying in TV home shopping was higher among those who had higher propensity for materialism, who took a serious view of markers or friends. Those who abuse their credit cards were more likely to have TV home shopping addiction.

• 대한치과의사협회지
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• 제58권3호
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• pp.152-168
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• 2020

The propensity score matching method is a statistical method used to reduce selection bias in observational studies and to show effects similar to random allocation. There are many observational studies in dentistry research, and differences in baseline covariates between the control and case groups affect the outcome. In order to reduce the bias due to confounding variables, the propensity scores are used by equating groups based on the baseline covariates. This method is effective, especially when there are many covariates or the sample size is small. In this paper, the propensity score matching method was explained in a simple way with a dental example by using R software. This simulated data were obtained from one of retrospective study. The control group and the case group were matched according to the propensity score and compared before and after treatment. The propensity score matching method could be an alternative to compensate for the disadvantage of the observation study by reducing the bias based on the covariates with the propensity score.

• Journal of Preventive Medicine and Public Health
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• 제57권1호
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• pp.1-7
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• 2024

Objectives: Adjusting for potential confounders is crucial for producing valuable evidence in outcome studies. Although numerous studies have been published using the Korea National Health Insurance Claim Database, no study has critically reviewed the methods used to adjust for confounders. This study aimed to review these studies and suggest methods and applications to adjust for confounders. Methods: We conducted a literature search of electronic databases, including PubMed and Embase, from January 1, 2021 to December 31, 2022. In total, 278 studies were retrieved. Eligibility criteria were published in English and outcome studies. A literature search and article screening were independently performed by 2 authors and finally, 173 of 278 studies were included. Results: Thirty-nine studies used matching at the study design stage, and 171 adjusted for confounders using regression analysis or propensity scores at the analysis stage. Of these, 125 conducted regression analyses based on the study questions. Propensity score matching was the most common method involving propensity scores. A total of 171 studies included age and/or sex as confounders. Comorbidities and healthcare utilization, including medications and procedures, were used as confounders in 146 and 82 studies, respectively. Conclusions: This is the first review to address the methods and applications used to adjust for confounders in recently published studies. Our results indicate that all studies adjusted for confounders with appropriate study designs and statistical methodologies; however, a thorough understanding and careful application of confounding variables are required to avoid erroneous results.

• Human Ecology Research
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• 제54권5호
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• pp.529-539
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• 2016

This study confirmed shopping behavior of Korean young overseas tourists and its effect on travel evaluation. I first identified core factors of travel activity preference, travel shopping propensity, and shopping products. The effect of shopping product satisfaction on tour satisfaction and post-tour intention was then investigated. Based on travel activities, tourists were grouped, and their characteristics were compared. An online survey method was performed to obtain data of 20's-30's Korean unmarried people, while factor analysis, regression analysis, chi-square test, analysis of variance (ANOVA), and cluster analysis were applied to analyze data. The results were as follows. First, six travel activities (city life, art/shopping, cultural experience, entertainment, field experience, and friendship), three shopping propensity (novelty/uniqueness, utility, and prestige), and four product groups (fashion goods, household goods, crafts, and foods) were found by factor analyses. Second, travel activity tended to influence shopping propensity, which then influenced shopping products preference. All factors of travel activity seemed to affect the three travel shopping propensities. Third, shopping satisfaction was shown to affect tour satisfaction, and posttour behavior. Finally, four tourist groups (active, social, pleasure, and passive) differed in terms of preferred tour activities, shopping propensity, and tour behavior. Active tourists rated the highest scores and passive ones rated the lowest for most evaluations.

• 간호행정학회지
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• 제12권3호
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• pp.434-443
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• 2006

Purpose: This study was to compare effects of preceptorship on nursing students' critical thinking propensity, clinical competency, and the satisfaction of clinical practice. Method: The subjects were 80 by preceptorship group and 51 by conventional method group. The data were analyzed by SPSS 12.0 program. Results: The subject's critical thinking propensity, clinical competency and satisfaction of clinical practices between the preceptorship group and the conventional method group revealed statistically significant difference. Subject's critical thinking propensity revealed significant correlations, along with the clinical competεncy and the satisfaction for clinical practice. And the clinical competency revealed statistically significant correlations with the satisfaction for clinical practice. Conclusion: Findings of this study reveals that the nursing students who had clinical practice by preceptorship showed higher scores in the critical thinking propensity, clinical competency, and the satisfaction for clinical practice than the conventional method group. Consequently, we are quite consciously encouraged to reinforce the preceptorship for realization of an effective clinical practice education for nursing students.

• 한국지구과학회지
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• 제40권4호
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• pp.436-445
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• 2019

This study presents how two types of integrated science and engineering lessons affect students' engineering problem solving skills and their perceptions of engineering. In total, 146 middle school students participated in this study. Eighty-six students participated in the Type I lesson (complete engineering design lesson with a science knowledge application) and 60 students participated in the Type II lesson (engineering design without a science knowledge application). Two main datasets, (1) students' Creative Engineering Problem Solving Propensity (CEPSP) measurement scores and (2) open-ended survey questions about students' perceptions of engineering, were collected before and after the lessons. The results of this study show that after participating in the Type I lesson, students' CEPSP scores significantly increased, whereas the CEPSP scores of the students who participated in the Type II lesson did not increase significantly. In addition, students who participated in the Type I lesson perceived engineering and the engineering integrated science lesson differently compared to the students who participated in the Type II lesson. The results of this study show that engineering integrated science, technology, engineering & mathematics (STEM) lessons should include a complete engineering design and a science knowledge application to improve students' engineering problem solving skills.

• 응용통계연구
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• 제29권2호
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• pp.389-398
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• 2016

본 연구에서는 신용보증기금으로부터 보증받은 기업의 미시적 성과를 분석하기 위해 비보증기업과 비교 분석하였다. t-test나 회귀모형과 같은 단순모형으로 비교하게 되면 선택편의에 의해 실제 보증성과를 나타낼 수 없다. 이러한 문제점을 해결하기 위해서, 선택편의를 보정한 회귀모형을 제안하였고 실제 자료에 적용하였다. 분석결과 비보증기업에 비하여 보증기업의 미시적 성과를 확인할 수 있었다.