• Communications for Statistical Applications and Methods
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• v.31 no.1
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• pp.1-35
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• 2024

The assumption of homoscedasticity is one of the most crucial assumptions for many parametric tests used in the biological sciences. The aim of this paper is to compare the empirical probability of type I error and the power of ten parametric and two non-parametric tests for homoscedasticity with simulations under different types of distributions, number of groups, number of samples per group, variance ratio and significance levels, as well as through empirical data from an agricultural experiment. According to the findings of the simulation study, when there is no violation of the assumption of normality and the groups have equal variances and equal number of samples, the Bhandary-Dai, Cochran's C, Hartley's Fmax, Levene (trimmed mean) and Bartlett tests are considered robust. The Levene (absolute and square deviations) tests show a high probability of type I error in a small number of samples, which increases as the number of groups rises. When data groups display a nonnormal distribution, researchers should utilize the Levene (trimmed mean), O'Brien and Brown-Forsythe tests. On the other hand, if the assumption of normality is not violated but diagnostic plots indicate unequal variances between groups, researchers are advised to use the Bartlett, Z-variance, Bhandary-Dai and Levene (trimmed mean) tests. Assessing the tests being considered, the test that stands out as the most well-rounded choice is the Levene's test (trimmed mean), which provides satisfactory type I error control and relatively high power. According to the findings of the study and for the scenarios considered, the two non-parametric tests are not recommended. In conclusion, it is suggested to initially check for normality and consider the number of samples per group before choosing the most appropriate test for homoscedasticity.

• Journal of the Korean Data and Information Science Society
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• v.19 no.3
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• pp.723-734
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• 2008

The main reason for deinterlacing is frame-rate conversion. The other reason for deinterlacing is of course improve clarity and reduce flicker. Using a deinterlacer can help clarity and stability of the image. Many deinterlacing algorithms are available in image processing literatures such as ELA and E-ELA. This paper propose a new statistical deinterlacing algorithm based on statistical tests such as the Bartlett test, the Levene test and the Kruskal-Wallis test. The results obtained from the proposed algorithms are found to be comparable to those from many well-known deinterlacers. However, the results in the proposed deinterlacers are found to be more efficient than other deinterlacers.

• Journal of the Korean Statistical Society
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• v.23 no.1
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• pp.207-216
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• 1994

Count data are often overdispersed, and an appropriate test for the existence of the overdispersion is necessary. In this paper we derive a score test based on the extended quasi-likelihood and the pseudolikelihood after adjusting to the Bartlett factor. Also, we compare it with Levene (1960)'s F-type test suggested by Ganio and Schafer (1992).

• The Journal of Industrial Distribution & Business
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• v.11 no.11
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• pp.29-38
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• 2020

Purpose: The problem of housing poverty among young people is a very important problem for the nation. Therefore, the main purpose of this paper is to identify the problems of the government's housing support policy for young people. And it is in presenting specific solutions by fully reflecting the opinions of experts. Research design, data and methodology: This study consisted of analyzing the following three research topics: 1) the differences of youth residential support housing policy impact on young adults' housing stability, 2) the problems and solutions of youth housing support policy, and 3) the differences of experts' opinions on the impact of government policy on youth housing stability. The subject of this study is the government's seven housing policies for young people. The targets include Happy Public Rental Housing (Happiness Housing), Station Area Rental Housing for youth (Station Area 2030), Public Dormitory for College Students (Public Dormitory & Hope Dormitory), Jeonse Rental Housing for College Students (Subject Lease Rental Housing for College Students), Social Housing for Young People, and Share House. The data was organized through expert surveys from 1st to 30th June 2020. The experts surveyed include professors & researchers, public officer & public institutions staff, and private developers of young adults' housing. The methodology of analysis on the problem and the solution of government policy was Frequency analysis. And analysis methods on differences of experts' opinion were ANOVA, Levene' test, and Schefe test. Results: Problems in Government's youth residential support housing policy include high rents, lack of supply, difficulty in acquiring rental housing, inconvenience in using shared spaces, conflicts with cohabitants, and invasion of privacy. Solutions include expanding supply to urban areas, establishing long-term plans, securing privacy, diversifying business methods, establishing platforms for rental housing transactions, and expanding various public support (financial support, etc). Conclusions: There was a difference in perception among groups of experts on the impact of public rental housing (called 'happiness housing') in youth housing stability. It is very urgent to come up with the most reasonable policy to support youth housing. This requires in-depth discussions by experts to narrow their differences.

• Journal of Korean Public Health Nursing
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• v.23 no.2
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• pp.199-206
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• 2009

Purpose: This study was designed to compare health habit and self-rated health status among early adulthood women in 1995, 2001, and 2007. Also, it was performed to determine correlations between health habits and self-rated health status. Methods: This research was investigated to identify a transition of health habits and self-rated health status. Participants who agreed to participate in the study were 18~25years old college women. Data was collected from 380 college students in 1995, 196 college students 2001, and 411 college students in 2007. Health habit assessment questionnaire was developed by authors. The reliability of the questionnaire were Cronbach $\alpha$=.87. Cronbach $\alpha$=.85, Cronbach $\alpha$=.90. The visual analogue scale which had 100 self-rating scores was used. All statistical analyses were used the Statistical Package for Social Sciences for Windows, Statistical analyses included descriptive statistics, Levene's test, repeated measure ANOVA, Brown-Forsythe test, Turkey test, Games-Howell test, and Pearson correlation coefficient test. Results: Health habit level, and self-rated heath status were significantly increased over time after 1995. Health habits was correlated with self-rated health status. Conclusion: Health habits and self-rated health status were influenced by health environments. Health practitioner can use perceived health status to access health habits.

• KDI Journal of Economic Policy
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• v.41 no.1
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• pp.43-58
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• 2019

Since 2009, electricity consumption has developed a unique seasonal pattern in South Korea. Winter loads have sharply increased, and they eventually exceeded summer peaks. This trend reversal distinguishes these load patterns from those in the USA and the EU, where annual peaks are observed during the summer months. Using Levene's test, we show statistical evidence of a rise in temperature but a decrease in variance over time regardless of the season. Despite the overall increase in the temperature, regardless of the season there should be another cause of the increased demand for electricity in winter. With the present study using data from 1991 to 2012, we provide empirical evidence that relatively low electricity prices regulated by the government have contributed significantly to the rapid upward change in electricity consumption, specifically during the winter months in the commercial sector in Korea.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.1
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• pp.25-28
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• 2018

Objectives: This study aimed to describe recent patterns in the types of statistical test used in original articles that were published in Journal of the Korean Association of Oral and Maxillofacial Surgeons. Materials and Methods: Thirty-six original articles published in the Journal in 2015 and 2016 were ascertained. The type of statistical test was identified by one researcher. Descriptive statistics, such as frequency, rank, and proportion, were calculated. Graphical statistics, such as a histogram, were constructed to reveal the overall utilization pattern of statistical test types. Results: Twenty-two types of statistical test were used. Statistical test type was not reported in four original articles and classified as unclear in 5%. The four most frequently used statistical tests constituted 47% of the total tests and these were the chi-square test, Student's t-test, Fisher's exact test, and Mann-Whitney test in descending order. Regression models, such as the Cox proportional hazard model and multiple logistic regression to adjust for potential confounding variables, were used in only 6% of the studies. Normality tests, including the Kolmogorov-Smirnov test, Levene test, Shapiro-Wilk test, and $Scheff{\acute{e}}^{\prime}s$ test, were used diversely but in only 10% of the studies. Conclusion: A total of 22 statistical tests were identified, with four tests occupying almost half of the results. Adoption of a nonparametric test is recommended when the status of normality is vague. Adjustment for confounding variables should be pursued using a multiple regression model when the number of potential confounding variables is numerous.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.3
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• pp.597-610
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• 2014

The purpose of this study was to inquiry of influence of Meister high school and specialized vocational high school' students on career maturity in problem solving ability domain of test for enhanced employ ability & upgraded proficiency. Research subjects and region were sophomore students of each one of Meister high schools and specialized vocational high schools in Gwangju region. The sample(N=481) was drawn from 2 high schools and collected data were analyzed with SPSS using t-test, Pearson correlation and Levene's test. Items of problem solving ability domain of test for enhanced employ ability & upgraded proficiency were used test items developed in 2012. Career maturity test in Careernet site was used test items developed in 2001 which was made up 3 domains such as attitude, ability and action and 8 sub-regions such as planning, attitude on the vocation, independence, self-understanding, rational decision-making, explore of information, knowledge of hope vocation and career exploration and preparation of action, and constituted 64 items. The results were as follows. Findings of the analysis in specialized vocational high school students demonstrated the positive results of rational decision-making and explore of information in problem solving ability test for enhanced employ ability & upgraded proficiency. Comparing career maturity influence on Meister high school with specialized vocational high school students about problem solving ability domain of test for enhanced employ ability & upgraded proficiency, Meister high school students' score were more high grade than specialized vocational high school students grade.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.102-107
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• 2008

Background : Malignant pulmonary nodules account for 30 to 40 percent of all solitary pulmonary nodules (SPNs). Therefore, characterization of SPNs is very important for treatment. Recently, dynamic CT has been widely used for tissue characterization and formation of differential diagnoses. The purpose of this study was to evaluate the ability of dynamic CT to formulate the differential diagnosis of SPNs. Materials and Methods : Nineteen patients with SPNs underwent dynamic CT (unenhanced scans, followed by a series of images at 20, 40, 60, 80, 100, 120, 140, 160, and 180 sec after intravenous injection of contrast medium). Diagnosis of SPN was performed based on pathologic findings in needle biopsy samples. Peak enhancement, net enhancement, slope of enhancement, and maximum relative enhancement ratio of the SPN were measured on dynamic CT, and Levene's test was performed to assess benignancy and malignancy. Results : Twelve SPNs were confirmed to have malignant pathology. There were no significant differences between benign and malignant nodules with respect to peak enhancement (p=0.787), net enhancement (p=0.135), or slope of enhancement (p=0.698). The maximal enhancement ratio was increased in malignancy compared to benignancy, but the difference was not statistically significant (p=0.094). Conclusion : In our study, the hemodynamic characteristics of dynamic CT were not significantly different between benign and malignant nodules. Therefore, long-term studies of larger patient samples are required to confirm our findings.

• Journal of Environmental Science International
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• v.20 no.9
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• pp.1183-1190
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• 2011

This study was aimed to establish the evaluating protocol and standard assessment for genetically modified (GM) hot pepper and to find out a proper statistic method to analyze for equality of agricultural characters between GM and non-GM pepper lines. GM and non-GM hot pepper lines were cultivated in two GMO fields in the middle region of Korea and total of 52 agricultural characters were collected during the plant growing season for 4 years, 2007 to 2010. Levene's test was conducted to confirm the homogeneity of raw data before statistic analysis. Two-way ANOVA in the multivariate tests and t-test were conducted to analyze 52 agricultural characters in order to find out the equality between H15 and P2377. From the statistical analysis through two-way ANOVA, 16 out of 16 plant growth traits, 9 out of 18 green fruit traits and 7 out of 18 red fruit traits among 4 years and 9 out of 16 plant growth traits, 4 out of 18 green fruit traits and 3 out of 18 red fruit traits between H15 and P2377 have shown the statistic differences. With the same raw data of 52 agricultural characters, t-test was also conducted. Based on the result from t-test, only 1 out of 16 plant growth traits, 2 out of 18 green fruit traits and 1 out of 18 red fruit traits have shown the differences between H15 and P2377, so that it was concluded that there is no statistic difference between H15 and P2377 in terms of agricultural characters. Also, the t-test is a proper statistic method to analyze each trait between GM and its control lines in order to evaluate agricultural characters.