• The Journal of the Korean dental association
• /
• v.58 no.3
• /
• pp.152-168
• /
• 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 Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.4
• /
• pp.367-377
• /
• 2021

Objectives: Taxi drivers are exposed to various hazards, such as long periods of sedentary work and traffic-related air pollutants. However, studies on the health effects among taxi drivers in South Korea are insufficient. Methods: To assess subclinical hematologic change related to cardiovascular disease among male taxi drivers, we analyzed data from the second Korean National Environmental Health Survey. Fifty-nine taxi drivers and 1,912 controls were included in the analysis. Propensity score matching was performed to adjust for age, body mass index, and urinary cotinine. A total of 295 subjects were matched with 59 taxi drivers. Leukocyte count, platelet count, hematocrit, triglyceride, total cholesterol, HDL cholesterol land total IgE of the taxi drivers were compared with the control groups. Results: Taxi drivers showed significantly elevated blood leukocytes and platelets. Serum total IgE was significantly reduced in taxi drivers. However, blood leukocytes, platelets, and serum total IgE were not significantly correlated with work period among taxi drivers. Conclusions: Regarding the change of the blood leukocyte count, platelet count, and serum total IgE, taxi driving has the possibility to be associated with peripheral inflammation, humoral immunity and cardiovascular risk.

• The Journal of Fisheries Business Administration
• /
• v.53 no.3
• /
• pp.85-101
• /
• 2022

This study analyzed the performance of the national fishing port development project, which lacked ex-post impact evaluation despite a lot of investment in terms of fishery income opportunities. Using micro data from the Census of Agriculture, Forestry, and Fisheries, the sales amount of fishery products and the proportion of fishery-related businesses were used as performance indicators. The fishery households in the fishing port area (treatment group) and those not in the area (control group) were classified through data pre-processing, and factors unrelated to the fishing ports were controlled using the propensity score matching difference-in-difference method. The analysis target is six fishing ports with large investment in from 2010 to 2014. As a result of the analysis, it was confirmed that the sales of fishery products increased significantly in four of the six fishing ports, and the proportion of fishery-related businesses increased in two fishing ports. The analysis method of this study can be fully utilized in the evaluation of the Fishing Community New Deal 300 Project, which is in need of performance analysis.

• The Korean Journal of Gastroenterology
• /
• v.72 no.5
• /
• pp.271-273
• /
• 2018

내시경 시술 전 일시적으로 항응고제를 중단하는 것은 위장관 출혈의 위험과 혈전색전증의 위험 사이에 적절한 균형을 잡기 어렵기 때문에 논란의 여지가 많다. 와파린은 새로운 경구용 항응고제(direct oral anticoagulant agent, DOAC)보다 임상의에게 더 친숙하고, 효과를 쉽고 빠르게 전환시킬 수 있다는 장점이 있지만 복잡한 약역동학 특징과 좁은 치료적 범위 때문에 관리가 어렵다. 반면, DOAC는 약물의 모니터링 및 용량 조절 없이 정해진 용량으로 처방이 가능하며, 빠르게 작용하고, 반감기가 짧아 관리가 쉽지만 해독제가 없다는 단점이 있다. 이전 연구들에서 DOAC를 복용한 환자들은 와파린을 복용한 환자들보다 시술과 관련되지 않은 위장관 출혈의 위험이 높았다고 보고한 바 있다. 하지만 시술과 관련된 위장관 출혈 위험에 대하여는 알려진 바가 없는 실정이다. 미국이나 유럽 내시경 가이드라인들에서는 저위험 내시경 시술을 받는 환자들에서는 와파린과 DOAC를 유지하도록 권고하고 있으며, 고위험 시술의 경우에는 와파린를 사용하는 환자들에서 헤파린 교량 요법(heparin bridging)을 시행하도록 권고하고 있다. 임상적으로 DOAC를 사용하는 환자들 또한 혈전색전증을 예방하기 위하여 헤파린 교량 요법을 시행해볼 수 있는데, 와파린 및 DOAC의 헤파린 교량 요법과 관련된 출혈 및 혈전색전증 위험의 차이 또한 명확하지 않다. 따라서 저자들은 1) 와파린과 DOAC 치료를 받는 환자들에서의 출혈, 혈전색전증 및 사망의 위험을 비교하고자 하였으며, 2) 13종류의 고위험 내시경 시술 중에서 시술별 위험을 비교하고, 3) 헤파린 교량 요법이 합병증의 발생을 증가시키지 않는지 확인하고자 본 연구를 진행하였다. 일본 대규모 국가 입원 환자 데이터베이스를 이용하여 2014년 4월부터 2015년 5월까지 시술 전 와파린 또는 DOAC(rivaroxaban, apixaban, dabigatran, edoxaban)를 복용하고, 13종류의 고위험 내시경 시술을 시행받은 20세 이상의 성인 환자 총 16,977명을 확인하였다. 고위험 시술은 용종 절제술, 내시경 점막절제술, 내시경 점막하박리술, 협착 부위의 풍선확장술, 내시경 지혈술, 내시경 정맥결찰술, 내시경 주사 경화요법, 내시경 괄약근절개술, 내시경 초음파 유도하 미세침 흡인 검사, 경피적 위루술을 포함하였다. 일대일 성향 점수 매칭 분석(propensity score matching, 나이, 성별, 체질량 지수, 기저 질환, 병원의 규모, 시술의 종류, 약물의 종류를 매칭)을 시행하여 와파린군과 DOAC군에서 시술 위장관 출혈 및 혈전색전증, 사망의 발생을 비교하였다. 또한 경구항혈전제와 헤파린 교량 치료 시행 유무에 따라, DOAC 단독군, 와파린 단독군, DOAC와 헤파린 교량 요법군, 와파린과 헤파린 교량요법군으로 나누어, 하위군(subgroup) 분석을 시행하였다. 5,046쌍이 성향 점수 매칭 분석에 포함되었으며, 와파린군에서 DOAC군보다 통계적으로 의미 있게 위장관 출혈의 비율이 높았다(12.0% vs. 9.9% p=0.02). 혈전색전증 발생률(5.4% vs. 4.7%)과 입원중 사망률(5.4% vs. 4.7%)은 양 군에서 의미 있는 차이는 없었다. DOAC 종류별로 나누어 하위군 분석을 시행하였을 때, 와파린군은 rivaroxaban군에 비하여 위장관 출혈의 비율이 높았으며, rivaroxaban군, dabigatran군에 비하여 혈전색전증의 비율이 높았고, 입원 중 사망률에서는 의미 있는 차이는 없었다. 내시경 시술의 종류로 보정하였을 때 위장관 출혈 및 혈전색전증, 사망률은 DOAC 단독으로 치료한 환자에서보다 와파린과 헤파린 교량 요법(bridging) 또는 DOAC과 헤파린 교량 요법을 시행한 환자에서 높았다. 시술 종류 중에서는 위루관 삽입술에 비하여 내시경 점막하박리술, 내시경 점막절제술 및 내시경 정맥류결찰술, 내시경 주사경화요법을 시행한 환자에서 위장관 출혈의 위험이 가장 높았으며, 하부 내시경 점막절제술, 하부 용종 절제술, 내시경적 유두괄약근절제술 또는 내시경 초음파 유도하 미세침 흡인 검사는 중등도 위험을 보였다.

• The Journal of Information Systems
• /
• v.25 no.1
• /
• pp.49-73
• /
• 2016

Purpose Though many information systems researchers have made various attempts to investigate the relationship between information technology capability and firm performance from diverse perspectives, we have not come to a conclusion yet with some mixed results. In this research, focusing on the adoption of Enterprise Resource Planning (ERP) systems by firms as a proxy measure for information technology capability, we reexamine whether the association is significantly positive. Design/methodology/approach Previous research on this topic had some limitations to the samples and analysis method. Some research focused only on the 1990s or early 2000s, and other studies failed to adequately compare the impact of ERP adoption on firm performance between the treatment group and the control group. In this research, extending previous analysis approaches with the matched sample comparison of IT leaders and the control group, we attempt to apply propensity score matching in combination with difference-in-difference analysis with a sample of Korean firms that adopted ERP systems in the late 2000s. We match ERP adopters and non-adopters with propensity score matching and compare their financial performance with difference-in-difference estimation between the pre- and post-adoption periods. Findings According to our analysis, we find no positive and significant relationship between ERP adoption and firm performance in profit ratios. This research shows that, contrary to the era of proprietary information systems, standardized information systems today have no additional competitive advantages over competitors.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.26 no.2
• /
• pp.523-531
• /
• 2016

This paper studies the empirical relationship between various privacy protection measures and personal information invasion experience of firms and individuals using rich and heterogeneous survey data. By analyzing PSM models. we get the following results: first, the treatment group which have more technical measures and/or IS investment tends to experience more privacy invasion than the control group which have less of them. second, the reverse causality, that is firms and individuals with more experience of privacy invasion tends to take more measure for personal information protection, is found to exist. From these result, we discuss proper privacy policies implications in respects of attackers benefits and individual irrationality.

• Health Policy and Management
• /
• v.30 no.3
• /
• pp.386-398
• /
• 2020

Background: We determined the differences in awareness of myocardial infarction and stroke according to the presence or absence of diabetes mellitus in the community. Methods: The 2018 Community Health Survey identified 20,812 people with diabetes mellitus aged 40-79 years. Using 1:1 matching by propensity score, 20,812 people without diabetes mellitus but with similar sociodemographic characteristics were selected as a comparison. Outcome variables were awareness of early symptoms of myocardial infarction and stroke and awareness of coping strategies in case of occurrence. Results: There was no significant difference between nondiabetic and diabetic people in terms of recognizing all early symptoms of myocardial infarction (nondiabetic, 42.7%; diabetic, 43.0%; p=0.43) and stroke (nondiabetic, 49.4%; diabetic, 49.4%; p=0.91). In addition, no significant difference was found between nondiabetic and diabetic people in the proportion of knowing correct emergency response to myocardial infarction (nondiabetic, 84.6%; diabetic, 84.4%; p=0.56) and stroke (nondiabetic, 81.3%; diabetic, 81.4%; p=0.77). Conclusion: Since people with diabetes are at greater risk of cardiovascular disease than the general public, it is important to lower the risk of disability and death by improving their awareness of early symptoms and correct emergency response to myocardial infarction and stroke.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.1
• /
• pp.200-208
• /
• 2009

Trend of R&D expenditure in Korea during the last 10 years, the R&D expenditure has been constantly increasing at an average rate of 10%. The government R&D ekpenditures or subsidies are increasing rapidly But the studies of evaluating impact of government R&D subsidies are few. This study attempts to empirically investigate the effects of government R&D subsidies on private firm's R&D investment in Korean industry by using Propensity score matching method which sign as to whether the relationship between government subsidies and private R&D investments is on stimulating or displacing private R&D expenditures. Empirically, a firm with government R&D subsidy are 733 million dollar more expenditure then don't receive any government R&D funding. Also Government R&D subsidies greatly increase (statistically significant) company financed R&D expenditures only for large firms but had no effect on the R&D expenditures of small & medium sized firms and venture firms.

• Journal of the Korea Convergence Society
• /
• v.11 no.7
• /
• pp.297-308
• /
• 2020

The purpose of this study is to compare and examine the understanding of the mutual relationship between the welfare attitude of the recipients and the non-recipients of the National Basic Livelihood Security. For this purpose, data from the Korea Welfare Panel Study 2016 (11th) were used and the data were analyzed by using difference analysis (DID) and structural equation AMOS after matching propensity scores (PSM) to 382 adults. The main results are as follows: First, Welfare attitudes were not significantly different for the National Basic Livelihood Security than the non- recipients. Second, Positive program welfare policy had a significant effect on welfare attitude for both the recipients and non-recipients of the National Basic Livelihood Security. Third, The value recognition government trust and social awareness did not have a significant effect on both the recipients of the National Basic Livelihood Security and the non-recipients. The results of this study provide basic data the establishment of policy directions to improve the quality of life of members of society.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.6878-6887
• /
• 2015

This study applies regression analysis and propensity score matching to analyze the agglomeration economies which the characteristics of tenancy affect the performance of the manufacturing industry based on industrial parks. The estimation main data are from Kis-Value, KIPRIS and FEMIS. The results show that the industrial park tenancy tends to work positively on the management performances. But there is no evidence that on-Park firms in the metropolitan areas(Gyeonggi-do) have higher management and innovative performances than the comparable firms. The firms that have lived for a long time in the industrial parks, are good in total sales, however, they have no significant efficiency in net profit, operating profit, and patents. The firms, having several branches of the industrial parks, have lower operating profit than others. Long-term and multiple tenant firms do not learn over time nor do they establish better linkages and networks.