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고차원 관측자료에서의 Q-학습 모형에 대한 이중강건성 연구
이효빈,김예지,조형준,최상범,Lee, Hyobeen,Kim, Yeji,Cho, Hyungjun,Choi, Sangbum 한국통계학회 2021 응용통계연구 Vol.34 No.3
동적 치료 요법(dynamic treatment regimes; DTRs)은 다단계 무작위 시험에서 개인에 맞는 치료를 제공하도록 설계된 의사결정 규칙이다. 모든 개인이 동일한 유형의 치료를 처방받는 고전적인 방법과 달리 DTR은 시간이 지남에 따라 변할 수 있는 개별 특성을 고려한 환자 맞춤형 치료를 제공한다. 최적의 치료 규칙을 파악하기 위한 회귀 기반 알고리즘 중 하나인 Q-학습 방법은 쉽게 구현될 수 있기 때문에 더욱 인기를 끌고 있다. 그러나 Q-학습 알고리즘의 성능은 Q-함수를 제대로 설정했는지의 여부에 크게 의존한다. 본 논문에서는 고차원 데이터가 수집되는 DTRs 문제에 대한 다양한 이중강건 Q-학습 알고리즘을 연구하고 가중 최소제곱 추정 방법을 제안한다. 이중강건성(double-robustness)은 반응변수에 대한 모형 혹은 처리변수에 대한 모형 둘 중 하나만 제대로 설정되어도 불편추정량을 얻을 수 있음을 의미한다. 다양한 모의실험 연구를 통해 제안된 방법이 여러 시나리오 하에서도 잘 작동함을 확인하였으며 실제 데이터 예제를 통해 방법론에 대한 예시를 제시하였다. Dynamic treatment regimes (DTRs) are decision-making rules designed to provide personalized treatment to individuals in multi-stage randomized trials. Unlike classical methods, in which all individuals are prescribed the same type of treatment, DTRs prescribe patient-tailored treatments which take into account individual characteristics that may change over time. The Q-learning method, one of regression-based algorithms to figure out optimal treatment rules, becomes more popular as it can be easily implemented. However, the performance of the Q-learning algorithm heavily relies on the correct specification of the Q-function for response, especially in observational studies. In this article, we examine a number of double-robust weighted least-squares estimating methods for Q-learning in high-dimensional settings, where treatment models for propensity score and penalization for sparse estimation are also investigated. We further consider flexible ensemble machine learning methods for the treatment model to achieve double-robustness, so that optimal decision rule can be correctly estimated as long as at least one of the outcome model or treatment model is correct. Extensive simulation studies show that the proposed methods work well with practical sample sizes. The practical utility of the proposed methods is proven with real data example.
이효빈,권연희,안정은 한국보육지원학회 2020 한국보육지원학회지 Vol.16 No.5
Objective: This study aimed to reveal pre-service early childhood teachers’ perception of children’s environmental education using concept mapping and demonstrating its importance. Methods: Based on Kane and Trochim’s(2007) procedure, 33 pre-service early childhood teachers conducted brainstorming and statement writing, and then the importance of selected statements were rated by 202 pre-service early childhood teachers. Selected statements were analyzed through multidimensional scaling and hierarchical cluster analysis. Results: Pre-service early childhood teachers perceived children’s environmental education as concept mapping with 2-dimensions and eight clusters. The following eight clusters were established (1) daily practice through hands on experience, (2) nature environment, (3) recognizing and coping with environmental issues, (4) environmental preservation practices, (5) environmental sensitivity and consideration, (6) purpose of children’s environmental education, (7) necessity for children’s environmental education (8) Practice through connection with child’s home and community. And then among the eight clusters, the most important was recognized as ‘daily practice through hands on experience’, and among the statements ‘young children learn through the method of playing in nature and experience nature’ was considered the most important. Conclusion/Implications: Based on these results, we discuss the importance of children’s environmental education of pre-service early childhood teachers and how to support to develop teacher’s training program.
Social Policy as Ethnic Conflict Appeasement in Turkey
이효빈 한국유럽학회 2014 유럽연구 Vol.32 No.4
This research seeks to explore how social policy affects ethnic appeasementin Turkey by analyzing the problem of Turkish welfare regime, its impacts onKurds and the newly enforced social policies. The Turkish welfare regimecloses the channels of social security to those who are employed in informalsector. The increasing number of informal workers in the Kurdish areas is themajor blind spot of the Turkish social security system. Since AKP came intopower, it expanded, created and institutionalized new social policies to targetthe poorest groups in the society such as CCT, In-kind Transfer Program, andUniversal Health Insurance. Although the government did not target certainethnic groups, the Kurdish people became the most beneficiary group from thesesocial assistance programs. These social assistances play a significant role ingaining popular support for AKP from the Kurdish regions. Finally, AKP wontwo elections (2007 and 2011) in most of the Kurdish regions.
이효빈,정윤선,서길준,권운용 대한응급의학회 2018 대한응급의학회지 Vol.29 No.1
Purpose: Tracheal intubation in a hemorrhagic airway is a difficult procedure because the visibility can be obscured by blood or vomitus. Several devices and methods have been developed to overcome such obstacles, but they are not available at all practical sites. Therefore, this study was conducted to assess the time and success rate of tracheal intubation according to the type of suction tip used in a hemorrhagic airway manikin model. Methods: This study was a randomized crossover manikin simulation study. We recruited 18 emergency physicians to perform intubation with suction using a Yankauer suction tip and a polyvinyl chloride (PVC) catheter suction tip in a hemorrhagic airway manikin model. We then measured the time and success rate of intubation for each suction tip. Results: The mean intubation time using the Yankauer suction tip was 42.3 seconds, and the mean intubation time using the PVC catheter suction tip was 91.1 seconds (p<0.001). Two cases of esophageal intubation occurred when the PVC catheter suction tip was used (success rate, 88.9%). In contrast, there was no esophageal intubation when the Yankauer suction tip was used (success rate, 100%) (p=0.217). Conclusion: Intubation of a hemorrhagic airway manikin model can be performed in a shorter time when a Yankauer suction tip is used than when a PVC catheter suction tip is used.