• Journal of the Korean Data and Information Science Society
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• v.27 no.1
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• pp.91-100
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• 2016

Fuzzy matching is proposed to make propensities of two groups similar with their propensity scores and a way to select control variable to make propensity scores with a process that shows how to acquire propensity scores using logic regression analysis, is presented. With such scores, it was a method to obtain an experiment group and a control group that had similar propensity employing the Fuzzy Matching. In the study, it was proven that the two groups were the same but with a different distribution chart and standardization which made edge tolerance different and we realized that the number of chosen cases decreased when the edge tolerance score became smaller. So with the idea, we were able to determine that it is possible to merge groups using fuzzy matching without a precontrol and use them when data (big data) are used while to check the pros and cons of Fuzzy Matching were made possible.

• The Korean Journal of Applied Statistics
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• v.30 no.3
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• pp.453-462
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• 2017

Double propensity score adjustment is an analytic solution to address bias due to incomplete matching. However, it is difficult to estimate the standard error of the estimated treatment effect when using double propensity score adjustment. In this study, we propose two bootstrap methods to estimate the standard error. The first is a simple bootstrap method that involves drawing bootstrap samples from the matched sample using the propensity score as well as estimating the standard error from the bootstrapped samples. The second is a complex bootstrap method that draws bootstrap samples first from the original sample and then applies the propensity score matching to each bootstrapped sample. We examined the performances of the two methods using simulations under various scenarios. The estimates of standard error using the complex bootstrap were closer to the empirical standard error than those using the simple bootstrap. The simple bootstrap methods tended to underestimate. In addition, the coverage rates of a 95% confidence interval using the complex bootstrap were closer to the advertised rate of 0.95. We applied the two methods to a real data example and found also that the estimate of the standard error using the simple bootstrap was smaller than that using the complex bootstrap.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.393-394
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• 2020

세 군 매칭을 수행하여 관찰 데이터를 구축하고 통계분석에 기반한 연구를 수행하는 경우가 종종 발생한다. 매칭작업은 각 군에 속한 개체의 성향점수를 서로 비교해 거리가 가까운 짝을 찾아야 하므로 카테시안 곱 만큼의 경우의 수를 따져야 하는 문제이고, 메모리 소요가 크다. 특히 세 군 매칭은 세 쌍의 거리가 가까운 triplet을 찾는 문제로, 세 개체 사이에 존재하는 세 개의 거리를 따져야 하기 때문에 메모리 소요가 두 군 매칭에 비해 훨씬 크다. 각 군에 속한 개체가 늘어나면 메모리소요가 기하 급수적으로 늘어나게 된다. R패키지에 포함된 TriMatch함수는 세 군 매칭 수행을 위해 가장 널리 사용되는 프로그램이다. 이 프로그램은 세 개체 사이의 세 개 거리가 가장 짧은 triplet을 찾는 방식으로 구현 되었다. 이 프로그램은 메모리 소요가 매우 커 각 군에 속한 개체의 수가 많아지면 메모리 부족 에러가 발생하는 경우가 많다. 본 연구에서는 세 군 매칭에 소요되는 메모리 소요를 줄일 수 있는 알고리즘을 제안하고자 한다. 이 알고리즘의 구현을 통해 각 군에 속한 개체가 늘어나도 안정적인 세 군 매칭 결과를 얻을 수 있을 것으로 기대한다.

• The Korean Journal of Applied Statistics
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• v.36 no.5
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• pp.415-445
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• 2023

Oftentimes, the time dependent treatment covariate and the time dependent confounders exist in observation studies. It is an important problem to correctly adjust for the time dependent confounders in the propensity score analysis. Recently, In the survival data, Hade et al. (2020) used a propensity score matching method to correctly estimate the treatment delay effect when the time dependent confounder affects time to the treatment time, where the treatment delay effects is defined to the delay in treatment reception. In this paper, we proposed the Cox model based marginal structural model (Cox-MSM) framework to estimate the treatment delay effect and conducted extensive simulation studies to compare our proposed Cox-MSM with the propensity score matching method proposed by Hade et al. (2020). Our simulation results showed that the Cox-MSM leads to more exact estimate for the treatment delay effect compared with two sequential matching schemes based on propensity scores. Example from study in treatment discontinuation in conjunction with simulated data illustrates the practical advantages of the proposed Cox-MSM.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2013.10a
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• pp.168-180
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• 2013

• Korean Journal of Social Welfare
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• v.66 no.3
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• pp.133-158
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• 2014

Over the past decades, changes in economic, social and demographic structures have pushed the growth of care employment across countries around the world. Women's increasing labor force participation has squeezed the time so far available for unpaid caregiving and led to increased demand for paid care services. Population aging and increasing needs for pre-school education also have contributed to the growth in demand for care services. As a result, care workers now comprise a large and growing segment of the labor force in many countries including South Korea. But, there are not a few problems. Especially, we take underpaid and undervalued care work very seriously. care work has been generally characterized as underpaid and undervalued compared with other work in developed and developing countries alike. This study tries to show current situation of care work and estimate the wage penalty for doing care work in Korea using official employment micro-data and applying propensity matching analysis. Especially, recent expansion of social service is a big step up for Korean Welfare State. But, there are not a few problems. Especially, we take underpaid and undervalued care work very seriously. This presentation tries to show current situation of care work and estimate the wage penalty for doing care work in Korea using official employment micro-data and applying propensity matching analysis.

• The Journal of the Korea Contents Association
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• v.19 no.10
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• pp.667-676
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• 2019

The purpose of this study was to assess the impact of childbirth on socioeconomic status changes of women. Data were collected from Korean Health Panel (2008-2015). A difference-in-differences model with propensity score matching was applied to assess the impact of childbirth on socioeconomic status changes. As a result, variables showing significant differences in the interaction terms indicating the impact of birth were the savings, economic activity, and occupational status. The impact of birth were significant in decreasing the amount of savings and negatively affecting women's economic activities, but in increasing the probability of full-time and regular employees in occupational status. Childbirth appears to have a negative impact on the home economics and socioeconomic status of women. The belief that home economies can be stabilized even after childbirth should be established, and a long-term and sustained support plan should be set up to realize this belief.

• Journal of Family Resource Management and Policy Review
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• v.27 no.4
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• pp.35-47
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• 2023

This study examined the effects of the revised and newly established family care leave and vacation systems in 2019 on the work-family balance of female managers. A total of 1,040 female managers with experience in using the systems were selected as the analysis subjects from the 2020 Women Managers Panel data. Propensity score matching and multiple regression analysis were conducted. The propensity score matching results showed that the family care time of the users of the family care leave was significantly lower than that of non-users, and both the work-family conflict and home-work conflict levels were significantly higher for the users than the non-users. For the family care vacation, the family care time of its users was significantly higher in national and local government organizations than that if its non-users. The results of multiple regression analysis indicated that the use of the family care leave had a significant positive impact on home-work conflict. These findings suggest that the current family care leave and vacation system have insufficient positive effects on work-family relationships.

• KDI Journal of Economic Policy
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• v.32 no.2
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• pp.27-53
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• 2010

This paper examines whether and how much vocational training raises an individual's earnings in Korea, using the Economically Active Population Survey. To overcome endogeneity of training, we apply fixed-effects and propensity-score matching (PSM) methods. Fixed-effects (PSM) results suggest that work-related training received in the previous one year increases a worker's monthly earnings by 2.6 to 4.7 (7.5 to 9.8) percent. Taken altogether, work-related training enhances a worker's earnings by a minimum of 2.6 and a maximum of 9.8 percent in Korea.

• Korean Journal of Social Welfare
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• v.63 no.4
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• pp.301-326
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• 2011

The major purpose of this study is to evaluate the impact of the long-term care insurance program. In order to estimate the impact of policy accurately, certain bias which might hamper the validity of this study has been removed by Propensity Score Matching(PSM) and Double Difference(DD) method from the semi-experimental design. To study the effects of long-term care insurance on the elderly and their family members as social outcome variable sand the quality of life of their family and satisfaction in family relationships, the third and fourth waves of Korea Welfare Panel are used to match experimental and comparative groups by the propensity score matching. Then, DD method, using the panel fixed effects model, is applied to estimate the differences of those groups'treatment effects before and after the policy implementation. As a result, it was found that the Quality of life on the elderly and their family members is statistically meaningless, while the satisfaction in family relationships has much increased after the policy implementation. The result has a limitation in that this evaluation is performed at the point when the long-term insurance program has not been ripened enough. However, there is an important implication on the significance of realizing the main goal of the long-term care insurance to improve the quality of life of the elderly and their family members and as for the potentiality of further system improvements.