• Journal of the Korean Statistical Society
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• 제32권1호
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• pp.1-10
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• 2003

We consider obtaining graphical summaries of uncertainty in estimates of parameters in nonlinear models. A nonlinear constrained optimization algorithm is developed for likelihood based confidence intervals for the functions of parameters in the model The results are applied to the problem of finding significance levels in nonlinear models.

• Journal of the Korean Data and Information Science Society
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• 제24권4호
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• pp.911-918
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• 2013

This study deals with the small sample likelihood based inference for the ratio of two normal variances. The small sample likelihood inference is an approximation method. The signed log-likelihood ratio statistic and the modified signed log-likelihood ratio statistic, which converge to standard normal distribution, are proposed for the normal variance ratio. Through the simulation study, the coverage probabilities of confidence interval and power of the exact, the signed log-likelihood and the modified signed log-likelihood ratio statistic will be compared. A real data example will be provided.

• Communications for Statistical Applications and Methods
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• 제15권5호
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• pp.655-666
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• 2008

Small sample likelihood based inference for the shape parameter of the inverse Gaussian distribution is the purpose of this paper. When shape parameter is of interest, the signed log-likelihood ratio statistic and the modified signed log-likelihood ratio statistic are derived. Hsieh (1990) gave a statistical inference for the shape parameter based on an exact method. Throughout simulation, we will compare the statistical properties of the proposed statistics to the statistic given by Hsieh (1990) in term of confidence interval and power of test. We also discuss a real data example.

• International Journal of Reliability and Applications
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• 제9권1호
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• pp.31-52
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• 2008

In this paper generalized version of the geometric distribution is introduced. This distribution can be considered as a two-parameter generalization of the discrete geometric distribution. The main statistical and reliability properties of this distribution are discussed. Two methods of estimation, namely maximum likelihood method and the method of moments are used to estimate the parameters of this distribution. Simulation is utilized to calculate these estimates and to study some of their properties. Also, asymptotic confidence limits are established for the maximum likelihood estimates. Finally, the appropriateness of this new distribution for a set of real data, compared with the geometric distribution, is shown by using the likelihood ratio test and the Kolmogorove-Smirnove test.

• Journal of the Korean Data and Information Science Society
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• 제15권1호
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• pp.251-261
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• 2004

The paper focuses primarily on the standard linear multiple regression model where the parameter of interest is a ratio of two regression coefficients. The general model includes the calibration model, the Fieller-Creasy problem, slope-ratio assays, parallel-line assays, and bioequivalence. We provide an orthogonal transformation (cf. Cox and Reid (1987)) of the original parameter vector. Also, we give some remarks on the difficulties associated with likelihood based confidence interval.

• 한국임상수의학회지
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• 제32권4호
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• pp.319-323
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• 2015

The performance of diagnostic test accuracy is usually summarized by a variety of statistics such as sensitivity, specificity, predictive value, likelihood ratio, and kappa. These indices are most commonly presented when evaluations of competing diagnostic tests are reported, and it is of utmost importance to compare the accuracies of diagnostic tests to decide on the best available test for certain medical disorder. However, it is important to emphasize that specific point values of these indices are merely estimates. If parameter estimates are reported without a measure of uncertainty (precision), knowledgeable readers cannot know the range within which the true values of the indices are likely to lie. Therefore, when evaluations of diagnostic accuracy are reported the precision of estimates should be stated in parallel. To reflect the precision of any estimate of a diagnostic performance characteristic or of the difference between performance characteristics, the computation of confidential interval (CI), an indicator of precision, is widely used in medical literatures in that CIs are more informative to interpret test results than the simple point estimates. The majority of peer-reviewed journals usually require CIs to be specified for descriptive estimates, whereas domestic veterinary journals seem less vigilant on this issues. This paper describes how to calculate the indices and associated CIs using practical examples when assessing diagnostic test performance.

• Asian Pacific Journal of Cancer Prevention
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• 제14권5호
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• pp.2753-2758
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• 2013

Various studies examining the relationship between Ezrin overexpression and response to chemotherapy and clinical outcome in patients with osteosarcoma have yielded inconclusive results. We accordingly conducted a meta-analysis of 7 studies (n = 318 patients) that evaluated the correlation between Ezrin and histologic response to chemotherapy and clinical prognosis (death). Data were synthesized in receiver operating characteristic curves and with fixed-effects and random-effects likelihood ratios and risk ratios. Quantitative synthesis showed that Ezrin is not a prognostic factor for the response to chemotherapy. The positive likelihood ratio was 0.538 (95% confidence interval [95% CI], 0.296- 0.979; random-effects calculation), and the negative likelihood ratio was 2.151 (95% CI, 0.905- 5.114; random-effects calculations). There was some between-study heterogeneity, but no study showed strong discriminating ability. Conversely, Ezrin positive status tended to be associated with a lower 2-year survival (risk ratio, 2.45; 95% CI, 1.26-4.76; random-effects calculation) with some between-study heterogeneity that disappeared when only studies that employed immunohistochemistry were considered (risk ratio, 2.97; 95% CI, 2.01- 4.40; fixed-effects calculation). To conclude, Ezrin is not associated with the histologic response to chemotherapy in patients with osteosarcoma, whereas Ezrin positivity was associated with a lower 2-year survival rate regarding risk of death at 2 years. Expression change of Ezrin is an independent prognostic factor in patients with osteosarcoma.

• Nutrition Research and Practice
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• 제18권2호
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• pp.239-256
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• 2024

BACKGROUND/OBJECTIVES: Over the past 10 yrs, the prevalence of diabetes in Korea has continued to incline, and the importance of lifestyle modification to manage diabetes has been highlighted. For patients with diabetes, carbohydrate intake reduction is effective in improving glycemic control; thus, we aimed to analyze the effect of carbohydrate intake ratio and suggest an appropriate carbohydrate intake ratio. SUBJECTS/METHODS: Using the 8th Korea National Health and Nutrition Examination Survey (2019-2021), we analyzed the data including participants aged 30 yrs or older with diabetes, and they were stratified into good and poor glycemic control groups. To analyze the correlation between the dietary behavior characteristics of participants with diabetes and the carbohydrate intake ratio, sociodemographic characteristics, dietary behavior, and health behavior were adjusted, and multivariate logistic regression analysis was conducted to present the adjusted odds ratio and 95% confidence interval (CI). RESULTS: In the unadjusted crude model, when carbohydrate intake ratio in total energy intake increased by 1%, the likelihood of poor glycemic control increased by 1.007-fold (95% CI, 0.998-1.016; P = 0.121). In model 1, which uses age and sex as adjustment variables, an increase of up to 1.011-fold was possible (95% CI, 1.001-1.021; P = 0.008). In model 2, which added variables such as diabetes duration, frequency of fruit consumption, frequency of lunch and, frequency of dinner, the risk of poor glycemic control increased by 1.010-fold as the carbohydrate intake ratio increased (95% CI, 0.998-1.022; P < 0.001). CONCLUSION: This study confirmed that as the ratio of carbohydrate intake to total energy intake increases the likelihood of poor glycemic control also increases in patients with diabetes. Therefore, to improve glycemic control in patients with diabetes, controlling the carbohydrate intake may be helpful.

• 지역사회간호학회지
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• 제30권1호
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• pp.90-98
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• 2019

Purpose: The purpose of this study is to identify the association between maternal feeding practices and excessive weight gain in infants. Methods: This study adopted a cross-sectional design and included 240 pairs of mothers and their infants (129 boys and 111 girls) in public healthcare centers in the Daejeon area in South Korea. Via multivariate analyses, the association between maternal feeding practices and excessive weight gain in infants was identified. Results: Among 240 infants in this study, 39 (16.3%) infants gained excessive weight during 12 months after birth. Using multivariate logistic regression with adjustment for covariates, more than 7 months of exclusive breastfeeding was associated with a reduced likelihood of excessive weight gain in infants during the 12 months after birth (adjusted odds ratio: 0.39, 95% confidence interval: 0.02~0.81, p=.029). Conclusion: Based on these results, nurses in communities and clinics should educate mothers on the importance of longer durations of exclusive breast feeding and develop strategies for encouraging such behavior. Furthermore, support for exclusive breast feeding should be provided in various settings.

• 한국산학기술학회논문지
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• 제18권4호
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• pp.408-417
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• 2017

본 연구의 목적은 의료기관 간호사 확보수준이 수술한 암환자의 원내 사망과 원내 감염에 어떠한 영향을 미치는지 알아보고자 하였다. 이차자료를 이용하였으며, 2012년 상반기에 260개 의료기관에서 수술 후 사망률이 높은 6개 암으로 수술받은 암환자 24,510명을 대상으로 하였다. 단순 로지스틱 회귀분석과 일반화추정방정식(GEE) 모형을 이용하여 분석하였다. 환자 및 의료기관 특성(기관 종별 유형, 소재지, 수술건수)을 보정 후, 사망 가능성은 간호사 확보수준 0-1등급에 비해 2-3등급 군(odds ratio [OR], 1.46; 95% confidence interval [CI], 1.00-2.11), 6-7등급 군(OR, 3.28; 95% CI, 1.87-5.74)에서 더 높은 것으로 나타났다. 병원 감염이 발생할 가능성은 간호사 1인당 침상수가 하나씩 증가할 때마다 증가하여, 0-1등급 군에 비해 2-3등급 군은 6.63배(95% CI, 3.00-14.62), 4-5등급 군은 5.79배(95% CI, 1.88-17.78), 6-7등급 군은 8.4배(95% CI, 1.82-38.84) 높은 것으로 나타났다. 낮은 간호사 확보수준은 환자안전과 의료의 질을 반영하는 지표인 높은 수술 후 원내 사망과 감염발생과 관련이 있었다. 이는 적절한 간호사 확보 수준은 수술 후 암 환자 결과와 관련 있음을 보여준다. 수술한 암환자의 의료의 질 향상과 환자 안전을 위해서는 적절한 간호사 수가 확보되어야 하며, 이를 위한 정책 유지가 필요하다.