• The Korean Journal of Applied Statistics
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• v.17 no.2
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• pp.337-346
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• 2004

The Pearson chi-square goodness-of-fit test and the likelihood ratio tests are usually used for testing independence in two-way contingency tables under random sampling. But both of these tests may provide false results for the contingency table with clustered observations. In this case we consider the generalized linear mixed model which includes random effects of clustering in addition to the fixed effects of covariates. Both the heterogeneity between clusters and the dependency within a cluster can be explained via generalized linear mixed model. In this paper we introduce several types of generalized linear mixed model for testing independence in contingency tables with clustered observations. We also discuss the fitting of these models through a real dataset.

• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.267-270
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• 2002

The evaluation of the cumulative distribution function of the noncentral $\chi^2$ distribution is required in approximate determination of the power of the $\chi^2$ test. This article provides an algorithm for evaluating the noncentral $\chi^2$ distribution function in terms of a single "central" $\chi^2$ distribution function and compared various approximations.ximations.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.483-490
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• 1997

The evalution of the cumulative distridution function of the noncentral $X^2$ distribution required in approxi-mate determination of the $X^2$ test. Many approximations to the cumulative distribution function of the noncentral $X^2$ distribution have been suggested. However, in selecting an approximations both simplicity and accuracy should be considered. In this note we compared various approximations in terms of accuracy and efficiency.

• The Mathematical Education
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• v.62 no.1
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• pp.151-173
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• 2023

In this study, we explored factors that affect high school student's affective attitude on mathematics with respect to the school mathematics instructoin, school mathematics assessment, mathematics textbook, private mathematics education, college entrance and career, and social atmosphere. Considering students' grade, major, academic level, gender, and school location, 1,029 high school students participated in the survey. To analyze the survey results, descriptive statistics, t-test, ANOVA, and chi-square test were conducted using SPSS ver 29.0. Results are as follows. First, generally, college entrance and career and school mathematics instruction affected students' affective attitude on mathematics. Second, according to student's academic level and gender, there was a statistically significant difference in the factors affecting the affective attitude on mathematics. Third, according to students' background, there was a statistically significant difference in students' responses to sub-categories of each factor. We suggested that to improve student's affective attitude on mathematics, diversity of the school mathematics instruction, improvement of the mathematics textbook, student's appropriate participation in the private mathematics education, improvement of student's perception of the utilization of the mathematics in the future and the importance of the mathemaitcs in the society, and parents' emotional support are needed.

• The Korean Journal of Applied Statistics
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• v.29 no.1
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• pp.123-132
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• 2016

We can achieve the principle of parsimony and efficiency if homogeneity for panel time series model is satisfied. We suggest a Rao test statistic and a Wald test statistic for the test of homogeneity for panel AR(1) and derived the limit distribution. We performed a simulation to examine statistics with the same chisquare distribution when number of the individual is small and in common with large. We also simulated to compare the empirical power of the statistics in a small panel. In application, we fit panel AR(1) model using regional monthly economical active population data and test homogeneity for panel AR(1). It is satisfied homogeneity, so it could be fitted AR(1) using the sample mean at the time point. We also compare the power of prediction between each individual and pooled model.

• The Korean Journal of Applied Statistics
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• v.23 no.5
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• pp.857-870
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• 2010

This study was conducted to investigate the relationship between the socio-demographic factors and the Korean consumers palatability evaluation grades with Hanwoo sensory evaluation data from 2006 to 2008 by National Institute of Animal Science. The dichotomy logistic regression model and the multinomial logistic regression model are fitted with the independent variables such as the consumer living location, age, gender occupation, monthly income, beef cut and the the palatability grade as the categorical dependent variable and tenderness, 리avor and juiciness as the continuous dependent variable. Stepwise variable selection procedure is incorporated to find the final model and odds ratios are calculated to nd the associations between categories.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.275-282
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• 2024

This study analyzed the factors that influence the development of gynecomastia by comparing blood test results and lifestyle between patients diagnosed with gynecomastia and normal control group. Independent sample t-test and chi-square tests were conducted to examine the mean differences among risk factors, and logistic regression analysis was used to calculate the relative risk ratio of various predictors influencing the development of gynecomastia. Age, HGB, HCT, TC, glucose, ALT, alcohol consumption, hair loss medication and medication for benign prostatic hyperplasia were identified as significant variables. Notably, the use of hair loss medication showed the highest univariate odds ratio of 15.79, while HGB decreased by a factor of 0.37. These results suggest that these could play a significant role in the onset of gynecomastia and could serve as foundational data for future diagnosis and management of the condition.

• Journal of Korean Society of Transportation
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• v.28 no.1
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• pp.51-61
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• 2010

The main objective of this paper is to analyze change of travel patterns according to public transportation reform. The paper uses data collected from Gyeongsan City. So far few researches, especially using before-and-after individual travel survey, have been conducted on analyzing effects of public transportation reform. For this research, some descriptive statistical analyses and statistical hypotheses tests were conducted. Furthermore, some empirical logit models were estimated for analyzing the individual effects of the public transportation reform. Finally, some important foundings, policy implications, and limitations of this research are discussed.

• Journal of Korean Society of Transportation
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• v.35 no.2
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• pp.105-115
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• 2017

Each year, a number of tourists visit Jeju Island, a popular tourist destination in the Republic of Korea. A large portion of the tourists (about 61%) use a rental car as a means of transportation. With this reason, the number of rental cars registered in Jeju was 15,517 in 2011, while the total number of the rental car has rapidly increased to 26,338 in 2015. For the same period, the number of rental car involved traffic accidents has been doubled. Thus, this study aims to analyze the rental car accidents' characteristics, clarifying primary factors related to rental car accidents in Jeju Island. To do this, 918 rental car accidents and 4,201 non-commercial passenger car accidents that occurred in Jeju island over the two years (2014-2015) were compared, using statistical methods such as chi-square test and z-test. The results show that the characteristics of rental car involved accidents are different from those caused by the passenger cars. Most of the rental car accidents in Jeju were caused by young drivers and drivers who had just obtained their driver's licenses. This study finds that driver immaturity, unfamiliar geography, and driving an unfamiliar vehicle are the main causes of the rental car accidents. Statistical analysis confirms that the characteristics of these accidents appeared significantly different from the passenger cars in terms of human and environmental factors. On the other hand, there is no clear evidence that vehicle-related characteristics are different between rental car and non-commercial passenger car accidents. The implications on transportation safety analysis and effective solutions to prevent rental car traffic accidents are discussed.

• Journal of the Korean Data and Information Science Society
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• v.27 no.2
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• pp.373-380
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• 2016

Even though Likert type data is ordinal scale, many researchers who regard Likert type data as interval scale adapt as parametric methods. In this research, simulations have been used to find out a proper analysis of Likert type data. The locations and response distributions of five point Likert type data samples having diverse distribution have been evaluated. In estimating samples' locations, we considered parametric method and non-parametric method, which are t-test and Mann-Whitney test respectively. In addition, to test response distribution, we employed Chi-squared test and Kolmogorov-Smirnov test. In this study, we assessed the performance of the four aforementioned methods by comparing Type I error ratio and statistical power.