• The Korean Journal of Applied Statistics
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• v.27 no.2
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• pp.227-237
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• 2014

We use the regression model with the indicator variables in the case that we use qualitative variables as some predictor variables in regression analysis. We use the ANCOVA(Analysis of Covariance) model when comparing the response variable among groups while statistically controlling for variation in the response variable caused by a variation in the covariate. DD-plot can be used as a graphical exploratory data analysis tool before the confirmatory data analysis. With the DD-plot, we can discriminate the difference of groups in the regression model with the indicator variables or the ANCOVA model at a glance. Making DD-plot does not demand the statistical model assumption about error terms in regression model. Several examples show the usefulness of DD-plots as a graphical exploratory data analysis tool for the regression analysis.

• Journal of ILASS-Korea
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• v.18 no.2
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• pp.81-86
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• 2013

To comply with the regulation of the reinforcing Clean Air Conservation Act, it is necessary for the semiconductor manufacturers to develop effective low-concentration acid gas abatement system to treat the flue gas. The low-concentration acid gas was found to be harder to deal with than the high-concentration one. In this study, the effect of various potential treatments such as air-assist nozzle spraying, magnetizing the scrubbing water, and adding surfactants to spraying and scrubbing water were investigate through the application of the statistical ANCOVA method, which was proved to be very useful tool when the inlet concentration of acid gas could not be controlled precisely and it affected the removal efficiency of the abatement system.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.19 no.2
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• pp.168-178
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• 2012

Purpose: The purpose of this study was to compare self-care behavior, diabetes-related stress and stress coping style among 3 blood glucose control groups (good, inadequate, and poor blood glucose control groups). Methods: Participants were 102 type 2 diabetic patients (good group: 41, inadequate group: 31, poor group: 30). Data were collected from Feb 19 to Mar 24, 2010 and were analyzed using Chi-square, Fisher's exact test and ANCOVA with SPSS/WIN 12.0. Results: Using ANCOVA with frequency of admission, and illness duration as covariates, significant differences were found among the 3 groups in self-care behavior (total score) and the exercise subscale. Using ANCOVA significant differences were found among 3 groups in diabetes-related stress (total score), emotional burden subscale and regimen distress subscale. Using ANCOVA no difference in stress coping was found among the 3 groups, but there was a significant difference in the problem-oriented coping subscale. Conclusions: Self-care behavior, diabetes-related stress, and stress coping style are factors influencing blood glucose control. The results of this study suggest that for improving blood glucose control, self care education program focused on diet and exercise in addition to stress management program for promoting problem oriented coping capability are recommended.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.2
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• pp.105-115
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• 2013

In Korea, the human skin tests to evaluate the anti-wrinkles and whitening effect have been accomplished in accordance with the KFDA guideline. Regarding the data of the visual assessment and machinery evaluation of the results for the human skin test, unpaired t-test have been used in order to compare between the test and the control groups and paired t-test for the comparison of effects for before and after. Descriptive statistics such as frequency analyses was used for the questionnaire evaluation data. In many cases of the European and American clinical test centers, the methodology and the statistical analysis were similar to ours. But, the documentation obtained by repeated application from identical individual has high relation. For this reason, it is desirable to apply RM ANCOVA and RM ANOVA to a visual assessment and machinery evaluation. We suggested that RM ANCOVA and RM ANOVA is the new approach to statistical analysis of human test data of functional cosmetics.

• Communications for Statistical Applications and Methods
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• v.19 no.5
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• pp.721-729
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• 2012

Various methods control the influence of a covariate on a response variable. These methods are analysis of covariance(ANCOVA), RANK ANCOVA, ANOVA of (covariate-adjusted) residuals, and Kruskal-Wallis tests on residuals. Covariate-adjusted residuals are obtained from the overall regression line fit to the entire data set that ignore the treatment levels or factors. It is demonstrated that the methods on covariate-adjusted residuals are only appropriate when the regression lines are parallel and covariate means are equal for all treatments. In this paper, we proposed the new nonparametric method on the ANCOVA model, as applying joint placement in a one-way layout on residuals as described in Chung and Kim (2007). A Monte Carlo simulation study is adapted to compare the power of the proposed procedure with those of the previous procedure.

• 한국데이터정보과학회:학술대회논문집
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• 2006.04a
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• pp.171-179
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• 2006

For the problem of variable selection in linear models, we consider the errors are correlated with V covariance matrix. Hocking's theorems on the effects of the overfitting and the underfitting in linear model are extended to the less than full rank and correlated error model, and to the ANCOVA model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1396-1403
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• 2014

This study aimed to investigate the effectiveness of Hope program, which were consisted in specific knowledge base, motivation, creativity to contribute development of creativity, problem-solving, learning motivation and learning behavior of college students. A total of 49 subjects were selected and took lessons of 14 hours from August 26 to September 13 over three weeks. Those were used for pre and post test to creativity test, problem-solving test, learning motivation test and learning behavior test(Lee, 2009). Because two groups didn't have homogeneity, ANCOVA test were used to verify the difference. The results of ANCOVA on the total scores of creativity, problem-solving, learning motivation and learning behaviors showed that there are statistically significant mean differences between the experiment group and the control group(p<.05).

• Restorative Dentistry and Endodontics
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• v.43 no.4
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• pp.43.1-43.7
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• 2018

• Journal of applied mathematics & informatics
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• v.32 no.3_4
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• pp.343-357
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• 2014

In many non-life insurance applications past data are given in a form known as the run-off triangle. Smoothing such data using parametric crisp regression models has long served as the basis of estimating future claim amounts and the reserves set aside to protect the insurer from future losses. In this article a fuzzy counterpart of the Hoerl curve, a well-known claim reserving regression model, is proposed to analyze the past claim data and to determine the reserves. The fuzzy Hoerl curve is more flexible and general than the one considered in the previous fuzzy literature in that it includes a categorical variable with multiple explanatory variables, which requires the development of the fuzzy analysis of covariance, or fuzzy ANCOVA. Using an actual insurance run-off claim data we show that the suggested fuzzy Hoerl curve based on the fuzzy ANCOVA gives reasonable claim reserves without stringent assumptions needed for the traditional regression approach in claim reserving.

• Culinary science and hospitality research
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• v.13 no.4
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• pp.57-66
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• 2007

The purpose of this study was to assess the effects of service quality, perceived sacrifice, food price and image on value. A total of 273 questionnaires were completed. MANOVA, ANOVA, and ANCOVA were used to measure the main effects and mediating effects of service quality and perceived sacrifice on the relationships among price, image, and value. The main effects of price on service quality, perceived sacrifice, and value were statistically significant. The main effects of image on service quality and value were statistically significant. As expected, when price, service quality, and perceived sacrifice regressed on the value, they were statistically significant. Moreover, when image, service quality, and perceived sacrifice regressed on the value, they had statistically significant effects on value. The results demonstrated that service quality played a mediating role in the relationship between price and value.