• 응용통계연구
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• 제22권6호
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• pp.1249-1263
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• 2009

표본수 결정에서 요구되는 검정력 함수는 연구가설에 상응하는 가장 적절한 검정방법에 의한 것이어야 한다. 의학연구의 논문에 자주 나타나는 순위자료 또는 범주형 빈도자료의 분석에는 비모수적 방법이 적절하며, 본 논문에서는 단변량 및 이변량 순위변수에 대한 윌콕슨-만-휘트니(Wilcoxon-Mann-Whitney; WMW) 검정법에 의한 표본수 결정방법을 제시한다. 단변량 순위변수의 윌콕슨 검정에서는 귀무가설과 대립가설 하의 분산을 이용한 표본수 공식이 귀무가설 하의 분산만 이용한 표본수 공식보다 정확하지만, 대립가설 하의 분산식에 나타나는 확률값이 일반적으로 알려져 있지 않으므로 이 확률값의 추정이 문제가 된다. 모의실험으로 두 방법에 대한 장, 단점을 알아본다. 효능과 안전성의 이변량 순위변수에서는 이변량 WMW 검정법에 의한 표본수 결정방법이 모수적 검정법에 의한 표본수 결정방법보다 더욱 바람직하다.

• Journal of the Korean Data and Information Science Society
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• 제23권1호
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• pp.209-218
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• 2012

The method of generalized estimating equations (GEEs) provides consistent esti- mates of the regression parameters in a marginal regression model for longitudinal data, even when the working correlation model is misspecified (Liang and Zeger, 1986). In this paper we compare the estimators of parameters in GEE approach. We consider two aspects: coverage probabilites and efficiency. We adopted to ordinal responses th results derived from binary outcomes.

• 대한간호학회지
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• 제44권5호
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• pp.542-551
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• 2014

Purpose: This study was done to examine the incidence of oral mucositis in hematopoietic stem cell transplantation patients and to identify factors influencing oral mucositis and patient outcomes according to severity. Methods: In this retrospective study, data were collected from electronic medical records of 222 patients who had received hematopoietic stem cell transplantation. Oral mucositis was evaluated using WHO's assessment scale. Data were analyzed using Chi-square test, Fisher exact test, Spearman's correlation, Ordinal logistic regression, ANOVA and Kruskal-Wallis test. Results: A total of 69.8% of the patients evaluated developed oral mucositis (grade II and over). As a results of ordinal regression, factors influencing oral mucositis severity were found to be diagnosis, type of transplantation, oxygen inhalation and the number of antiemetics administration before transplantation. The severity of oral mucositis was found to increase the days of hospitalization, days of TPN administration, days of using antibiotics and the number and dosage of analgesics. Conclusion: The results would help predict severity of oral mucositis in hematopoietic stem cell transplantation patients and suggest that provision of appropriate nursing assessment and oral care would improve patient outcomes.

• Communications for Statistical Applications and Methods
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• 제26권2호
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• pp.205-216
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• 2019

Diagnostic tests in medical fields detect or diagnose a disease with results measured by continuous or discrete ordinal data. The performance of a diagnostic test is summarized using the receiver operating characteristic (ROC) curve and the area under the curve (AUC). The diagnostic test is considered clinically useful if the outcomes in actually-positive cases are higher than actually-negative cases and the ROC curve is concave. In this study, we apply the stochastic ordering method in a Bayesian hierarchical model to estimate the proper ROC curve and AUC when the diagnostic test results are measured in discrete ordinal data. We compare the conventional binormal model and binormal model under stochastic ordering. The simulation results and real data analysis for breast cancer indicate that the binormal model under stochastic ordering can be used to estimate the proper ROC curve with a small bias even though the sample sizes were small or the sample size of actually-negative cases varied from actually-positive cases. Therefore, it is appropriate to consider the binormal model under stochastic ordering in the presence of large differences for a sample size between actually-negative and actually-positive groups.

• 응용통계연구
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• 제33권1호
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• pp.25-46
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• 2020

본 논문에서는 Bayesian spectral analysis regression (BSAR) 방법론을 이용한 베이지안 순서형 프로빗 준모수 회귀모형에 대해서 고찰한다. 순서형 프로빗 회귀모형은 순서가 있는 범주형 자료를 모형화하는 방법으로, 정규 분포의 분포함수의 역함수인 프로빗 연결함수를 이용해 각 범주의 확률과 설명변수을 연결함으로써 반응변수의 확률을 모형화한다. 베이지안 프로빗 회귀 모형은 정규 분포를 따르는 잠재변수를 도입함으로써 사후 분포 도출을 용이하게 하고, 절단점에 따라 나뉘어지는 잠재변수들의 값에 따라서 반응 변수들이 범주화된다. 본 논문에서는 이러한 잠재 변수 방법을 확장해 BSAR 방법론에 기반하여 단조증가/감소와 같은 형태제약을 반영할 수 있는 베이지안 이항형 및 순서형 프로빗 준모수 회귀모형에 대해 연구한다. 모의실험을 통하여 이항형 프로빗 준모수 회귀모형과 기존의 다른 모형들 간의 적합결과를 비교하고, 형태 제약에 따른 순서형 프로빗 준모수 회귀모형의 적합결과를 비교 분석하도록 한다. 아울러, 국민건강영양조사 제 7기 1차년도 (2016) 자료(Korean National Health and Nutrition Examination Survey (KNHANES), 2016)를 바탕으로, 본 논문에서 고찰한 이항형 및 순서형 프로빗 준모수 회귀모형을 적용하여, 흡연양태와 커피섭취 간의 관계에 대한 실증적 분석을 수행한다.

• 보건행정학회지
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• 제30권3호
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• pp.399-408
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• 2020

Background: The purpose of this study was to examine the impact of the regional characteristics on the accessibility of emergency care and the impact of emergency medical accessibility on the patients' prognosis and the emergency medical expenditure. Methods: This study used the 13th beta version 1.6 annual data of Korea Health Panel and the statistics from the Korean Statistical Information Service. The sample included 8,119 patients who visited the emergency centers between year 2013 and 2017. The arrival time, which indicated medical access, was used as dependent variable for multi-level analysis. For ordinal logistic regression and multiple regression, the arrival time was used as independent variable while patients' prognosis and emergency medical expenditure were used as dependent variables. Results: The results for the multi-level analysis in both the individual and regional variables showed that as the number of emergency medical institutions per 100 km² area increased, the time required to reach emergency centers significantly decreased. Ordinal logistic regression and multiple regression results showed that as the arrival time increased, the patients' prognosis significantly worsened and the emergency medical expenses significantly increased. Conclusion: In conclusion, the access to emergency care was affected by regional characteristics and affected patient outcomes and emergency medical expenditure.

• 기술혁신학회지
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• 제11권3호
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• pp.376-399
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• 2008

최근 연구개발 투자규모가 급속히 증가함에 따라 정부는 R&D사업의 투자효율성을 높이기 위한 다양한 정책을 구사하고 있다. 구체적으로 R&D사업에 대한 성과평가를 강화하고 평가결과를 예산의 조정 및 배분에 반영하는 등 성과중심의 평가체계를 정착시키기 위해 노력하고 있다. 이처럼 국가연구개발사업에 대한 평가가 성과중심으로 체계화되기 위해서는 R&D 성과물을 과학적 객관적으로 분석할 수 있는 성과지표의 개발이 필요하다. 이에 본 연구에서는 전 부처 연구개발사업에 공통으로 적용할 수 있는 성과지표인 SCI논문지표를 바탕으로 교육과학기술부 3대 연구개발사업에 대한 구체적인 사례분석을 실시하여 이들 사업이 우리나라 전체 R&D에서 차지하는 질적 양적 위상을 파악하고자 하였다. 이러한 분석을 위해 SCI 관련 기존지표와 더불어 4개의 신규지표를 소개하였고 신규지표들의 타당성 조사를 위해 모의실험을 실시하였다. 그 결과 보완된 순위보정영향력지수(ordinal rank normalized impact factor, omIF)가 분야간 비교 시 가장 적절한 성과지표인 것으로 분석되었다.

• 응용통계연구
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• 제22권2호
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• pp.341-353
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• 2009

두 군의 처리를 비교하는 임상시험에서 효능(efficacy)과 안전성(safety)이 동일하게 중요한 변수로 취급되는 경우에 이변량(bivariate) 반응변수로서 분석되고 연구계획의 단계에서도 이변량 표본수 결정방법이 사용되어야 한다. Thall과 Cheng (1999)은 효능과 안전성의 반응값이 이변량 이항(bivariate binary) 변수인 경우의 표본수 결정방법을 제시하였으며, 본 연구에서는 목표모수 설정과정은 기존의 연구와 같으나 월콕슨-만-휘트니(Wilcoxon-Mann-Whitney: WMW) 통계량에 근거한 검정법과 표본수 결정방법을 제시한다. Thall과 Cheng (1999)의 검정통계량은 변수 변환시킨 비율의 근사 정규성에 근거하는 반면에, WMW 통계량은 확률에 근거한 비모수적 방법으로 이변량 이항변수 뿐만 아니라 이변량 순위변수로 측정된 반응값에도 적용시킬 수 있다 Thall과 Cheng (1999)에 제시한 항암치료 임상연구의 두 예제에 위의 두 다른 방법으로 계산된 표본수를 비교한 결과, Thall과 Cheng (1999)의 첫째 예제에서는 이변량 WMW 방법에 의한 표본수가 더욱 작았으나 둘째 예제에서는 더욱 큰 것으로 나타났다.

• Communications for Statistical Applications and Methods
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• 제29권4호
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• pp.421-439
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• 2022

Phase I dose-finding trials are essential in drug development. By finding the maximum tolerated dose (MTD) of a new drug or treatment, a Phase I trial establishes the recommended doses for later-phase testing. The primary toxicity endpoint of interest is often a binary variable, which describes an event of a patient who experiences dose-limiting toxicity. However, there is a growing interest in dose-finding studies regarding non-binary outcomes, defined by either the weighted sum of rates of various toxicity grades or a continuous outcome. Although several novel methods have been proposed in the literature, accessible software is still lacking to implement these methods. This study introduces a newly developed R package, UnifiedDoseFinding, which implements three phase I dose-finding methods with non-binary outcomes (Quasi- and Robust Quasi-CRM designs by Yuan et al. (2007) and Pan et al. (2014), gBOIN design by Mu et al. (2019), and by a method by Ivanova and Kim (2009)). For each of the methods, UnifiedDoseFinding provides corresponding functions that begin with next that determines the dose for the next cohort of patients, select, which selects the MTD defined by the non-binary toxicity endpoint when the trial is completed, and get oc, which obtains the operating characteristics. Three real examples are provided to help practitioners use these methods. The R package UnifiedDoseFinding, which is accessible in R CRAN, provides a user-friendly tool to facilitate the implementation of innovative dose-finding studies with nonbinary outcomes.

• 한국임상약학회지
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• 제26권1호
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• pp.33-39
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• 2016

Background: Elements of informed consent including capacity, disclosure, understanding, voluntariness, and permission of the participant, are all crucial for clinical trials to be legally and ethically valid. During the informed consent process, the patient information leaflet is an important information source which prospective research subjects can utilize in their decision-making. In the adequate provision of information, KGCP guideline necessitate 20 specific items, as well as the use language that individuals can understand. This study measures the vocabulary level of patient information leaflets in an effort to provide an objective evaluation on the readability of such material. Methods: The word difficulty of 13 leaflets was quantitatively evaluated using Kim kwang Hae's vocabulary grading framework, which was compared to the difficulty level of words found in the $6^{th}$ grade Korean textbook. The quantitative outcomes were statistically analyzed using chi-squared tests and linear by linear association for ordinal data. Results: There was a statistically significant difference between the vocabulary level and frequency of words in leaflets and the 6th Korean textbook. The leaflets were on average 260 sentences and about roughly 15 pages long, including lay language (easier or equal to language used in primary school) of around 12% less; technical language of around 4.5% more. As the vocabulary grades increase, there was a distinct difference in vocabulary level between Korean textbook and each information leaflet (p < 0.001). Conclusion: Patient information leaflets may fail to provide appropriate information for self-determination by clinical trial subject through the difficulty level of its wording. Improvements in the degree of patients' understanding and appropriate use of information leaflets are collaboratively equipped to strengthen patient's autonomy and therefore guaranteeing participant's rights.