• Journal of Distribution Science
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• v.16 no.1
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• pp.87-99
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• 2018

Purpose - The Export Infrastructure Strengthening Program(EISP) is a project to expand exports of agri-food products through providing customized export information to food distribution companies and supporting overseas information activities. A total of 39.6 billion won was provided by 2016. So, the purpose of this study is to analyze whether EISP is effective for expanding exports of agri-food products. Research design, data, and methodology - A simple average difference between the export performance of the policy beneficiaries and the non-policy beneficiaries can be biased if the export capacity or inherent characteristics of the enterprise are not taken into consideration. In order to solve the problem of such a bias, the propensity score matching(PSM) method has been employed in this study. PSM is a method of converting the characteristics of an export company into an index through logit analysis and then reducing the matching to one dimension to improve the accuracy of the performance measurement. Results - The balancing test was conducted to determine how the characteristics of the policy beneficiary group and the matched policy non-beneficiary group corresponded to each other. As a result of the test, we could not reject the null hypothesis that there was no difference between the two groups, so that after the matching, the two groups were similar and the explanatory variables were well controlled. Using the nearest neighbor matching with propensity score estimating through logit analysis, we estimated average treatment effect on the treated(ATT). The food companies participating the EISP had the effect of increasing the exports of $ 5.88 million. As a result, the number of export contracts increased by 11.77, the number of exporting countries by 7.52, the number of export items by 47.51, and the number of buyers' consultation by 3.50. And overseas marketing expenses increased by 35.92 million won. Except for the number of export contracts, other export performance results showed statistically significant results. Conclusions - As the EISP has a positive effect on the expansion of agro-food exports, efforts should be made to find out the limitations or problems of the policy in the future and to make a greater contribution to the increase of exports.

• Journal of Labour Economics
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• v.32 no.2
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• pp.125-150
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• 2009

This article analysed the effect of government intervention on the market failure in firm training in Korean. I used the Employment Insurance DB and the KISLINE DB and joined two data by the firm identification number 2004-2006 year. I estimated the effect of intervention of government by propensity score matching and difference-in-difference method to avoid of participation selection and endogeneity problem. The result is that government intervention on the firm training have made positive effect but it is not significant statistically. We have to investigate the market failure in firm training and to reassess the level of optimal firm training in Korea. After the study, the government intervention on the firm trainig will have to be rearranged.

• KDI Journal of Economic Policy
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• v.39 no.1
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• pp.1-18
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• 2017

This paper empirically studies the effect of public procurement on small and medium-sized enterprises (SMEs) in the Republic of Korea using firm-level data. Public procurement, the purchase of goods and services from private firms by the public sector, is regarded as an important policy measure for providing support to firms, particularly SMEs. This study uses establishment-level panel data of the mining and manufacturing sectors from the Korean National Bureau of Statistics (Statistics Korea) and procurement history from the Korean Public Procurement Service to empirically estimate the effects of public procurement on firms' productivity (total factor productivity) and survivability. Using a propensity score matching estimation method, we find that participating firms showed higher productivity than non-participating ones in the control group only for the year of participation, that is, 2009. After two years, in 2011, they exhibited significantly lower productivity. In contrast, establishments that participated in public procurement for SMEs in 2009 were more likely to survive than those that did not do so in 2011. These results can be interpreted as the negative consequences of government intervention. The market's efficiency enhancement is hindered if underserving companies survive owing to government intervention but fail to improve efficiency.

• Journal of Preventive Medicine and Public Health
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• v.57 no.1
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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.

• The Korean Journal of Applied Statistics
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• v.27 no.7
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• pp.1077-1095
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• 2014

Unlike randomized trial, statistical strategies for inferring the unbiased causal relationship are required in the observational studies. Recently, new methods for the causal inference in the observational studies have been proposed such as the matching with the propensity score or the inverse probability treatment weighting. They have focused on how to control the confounders and how to evaluate the effect of the treatment on the result variable. However, these conventional methods are valid only when the treatment variable is categorical and both of the treatment and the result variables are directly observable. Research on the causal inference can be challenging in part because it may not be possible to directly observe the treatment and/or the result variable. To address this difficulty, we propose a method for estimating the average causal effect when both of the treatment and the result variables are latent. The latent class analysis has been applied to calculate the propensity score for the latent treatment variable in order to estimate the causal effect on the latent result variable. In this work, we investigate the causal effect of adolescents delinquency on their substance use using data from the 'National Longitudinal Study of Adolescent Health'.

• Journal of Korea Technology Innovation Society
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• v.13 no.3
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• pp.446-458
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• 2010

All countries of the world have been spurring foreign direct investment consistently for securing of economic growth and growth engines, and Korea is no exception. Korea has been stimulating investment of high quality through various political support and the government has been publicizing it as an achievement. Based on the most of previous studies analyzed the results of foreign direct investment only on the view of domestic economy, this study supposes that foreign direct investment influences positively on management and innovation performance on companies, and evaluated effects of foreign direct investment by using Propensity score matching method. Analysis shows that foreign direct investment has positive influence on management and innovation performance before matching them. However, after matching them, the most statistical significance disappears. Consequently, foreign direct investment has limited effect on company's performance comparison on initial assumption. 'This study indicates that incentive policy of foreign direct investment would need to be amended, because effect of incentive policy was limited for firm's performance.

• 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.

• Journal of the Korean Regional Science Association
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• v.38 no.2
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• pp.21-41
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• 2022

The purpose of this study is to compare the differences in the subjective quality of life (QoL) perceived by residents in different settlement spaces such as urban vs. rural and Seoul Capital Area (SCA) vs. Non-Capital Area (NCA). Using the data of the 'Quality of Life Satisfaction Survey for Balanced Development' conducted nationwide by the Presidential Committee for Balanced National Development in 2018, a propensity score matching method was introduced to compare the differences between the types of settlement spaces. The results show that no significant difference is found between all the types in satisfaction with local life, and in the case of happiness, rural residents show a higher level than those living in cities. Looking at the quality of life by QoL domain, the QoL of urban residents in SCA is generally the highest in the basic living environment, medical care, and culture/leisure domains, while the QoL of rural residents in the job/income, environment, community, and welfare domains is higher than that of residents of SCA and NCA cities. Interestingly, in no domains NCA cities show their relative strength. These results show the value of rural areas in the face of increasingly prevailing urbanization trends, and suggests that the value of rural areas must be strengthened for rural development. It is necessary to pursue policy efforts such as rural regeneration based on spatial planning in order to respond to the disorganized development that damages the value of the rural environment and landscape and to harmoniously maintain and develop the rural settlement.

• Physical Therapy Rehabilitation Science
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• v.8 no.2
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• pp.67-73
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• 2019

Objective: The purpose of this study was to compare the differences in the length of hospital stay between hemorrhage stroke survivors with health insurance and those with medical care after controlling all factors except for the type of medical insurance by using the propensity score matching (PSM) method. Design: Retrospective cohort study. Methods: Data from the Korean National Centers for Disease Control and Prevention's In-Depth Discharge Injury Survey between the years 2006 and 2012 were used for analysis. A total of 4,538 cases were defined as persons with hemorrhagic stroke (I60-I62) based on the block of categories in the International Classification of Diseases (10th). In order to analyze the inpatient period differences depending on the type of health care, which reflects one's socio-economic level, the chi-square and t-test was conducted. Results: Frequency and percentage were presented, and regression analysis was used to determine the factors affecting the inpatient period. Age, severity of disease, treatment outcome, and post-discharge status were no longer statistically significant after matching. The inpatient period of the persons receiving medical aid benefits was found to be significantly longer than those with national health insurance (p<0.05). Conclusions: The factors influencing the inpatient period of hemorrhagic stroke survivors were treatment outcomes, severity of disease, hospital admission process, and the type of health care. It is necessary for systematic and comprehensive governmental management for persons with hemorrhagic stroke to be transferred to long-term care facilities.

• Journal of Labour Economics
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• v.36 no.1
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• pp.63-91
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• 2013

This paper analysed the training effects on wage and employment security by the non-standard worker types by using Economically Active Population Additional Survey data. Through propensity score matching method, we found that the regular workers' training effect on wage was 4.2%, that was very higher than 2.7% of fixed-term workers. Logistic regression analysis showed that the training participation itself did not affect on the regular workers' regular position continuance, but training duration affected. Just in fixed-term workers among non-standard workers, both of training participation and training duration affected the transition from non-standard position to regular position. The result that both training effects on wage and on employment were positive just in the fixed-term workers might be interpreted owing to the clear employment contract relation between employer and employees.