• Communications for Statistical Applications and Methods
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• v.29 no.5
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• pp.547-559
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• 2022

For a chi-squared test, which is a statistical method used to test the independence of a contingency table of two factors, the expected frequency of each cell must be greater than 5. The percentage of cells with an expected frequency below 5 must be less than 20% of all cells. However, there are many cases in which the regional expected frequency is below 5 in general small area studies. Even in large-scale surveys, it is difficult to forecast the expected frequency to be greater than 5 when there is small area estimation with subgroup analysis. Another statistical method to test independence is to use the Bayes factor, but since there is a high ratio of data dependency due to the nature of the Bayesian approach, the low expected frequency tends to decrease the precision of the test results. To overcome these limitations, we will borrow information from areas with similar characteristics and pool the data statistically to propose a pooled Bayes test of independence in target areas. Jo et al. (2021) suggested hierarchical Bayesian pooling models for small area estimation of categorical data, and we will introduce the pooled Bayes factors calculated by expanding their restricted pooling model. We applied the pooled Bayes factors using bone mineral density and body mass index data from the Third National Health and Nutrition Examination Survey conducted in the United States and compared them with chi-squared tests often used in tests of independence.

• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.529-540
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• 2015

A cross-over design is frequently used in clinical trials (especially in bioequivalence tests with a parametric method) for the comparison of two treatments. Missing values frequently take place in cross-over designs in the second period. Usually, subjects that have missing values are removed and analyzed. However, it can be unsuitable in clinical trials with a small sample size. In this paper, we compare single imputation methods in a $2{\times}2$ cross-over design when missing values exist in the second period. Additionally, parametric and nonparametric methods are compared after applying single imputation methods. A Monte-Carlo simulation study compares type I error and the power of methods.

• Journal of Wetlands Research
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• v.21 no.1
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• pp.66-76
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• 2019

Recently, natural disasters such as floods and droughts are frequently occurred due to climate change and the damage is also increasing. Wetland is known to play an important role in reducing and minimizing the damage. In particular, water level variability needs to be analyzed in order to understand the various functions of wetland as well as the reduction of damage caused by natural disaster. Therefore, in this study, we fitted water level series of Upo wetland in Changnyeong, Gyeongnam province to a proper time series model and residual test was performed to confirm the appropriateness of the model. In other words, ARIMA model was constructed and its residual tests were performed using existing nonparametric statistics, BDS statistic, and Close Returns Histogram(CRH). The results of residual tests were compared and especially, we showed the applicability of CRH to analyze the residuals of time series model. As a result, CRH produced not only accurate randomness test result, but also produced result in a simple calculation process compared to the other methods. Therefore, we have shown that CRH and BDS statistic can be effective tools for analyzing residual in time series model.

• The Korean Journal of Applied Statistics
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• v.23 no.6
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• pp.1081-1091
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• 2010

Clinical trials are often carried out as multi-center studies because the patients enrolled for a trial study are very limited in one particular hospital. In these circumstances, the use of an ordinary Jonckheere (1954) and Terpstra (1952) test for testing trend among several independent treatment groups is invalid. We propose a the stratified Jonckheere-Terpstra test based on van Elteren (1960)'s stratified test of Wilcoxon (1945) statistics and an application of our method is demonstrated through example data. A simulation study compares the efficiency of stratified and unstratified Jonckheere-Terpstra trend tests.

• Industrial Engineering and Management Systems
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• v.7 no.3
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• pp.228-244
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• 2008

ISO9000 set of standards has been widely applied in Iranian Automotive manufacturing industry. Regarding the effects of TQM and ISO9000 set of standards various studies have been conducted and different quantitative conclusions have been made. Due to lack of quantitative information, in many of the cases, using qualitative information becomes the best option. The qualitative nature of data in such cases, requires qualitative analysis methods that might lead to some challenging computational issues. This paper examines the impact of ISO9000: 2000 certification and its perceived benefits for an automotive manufacturing company. Using an empirical approach, the paper seeks to ascertain if certification has indeed improved the performance of the company. Our null hypothesis rotates around the effect of ISO9000: 2000 on the 4W's of an enterprise. To carry out the research, first we developed a couple of questionnaires including all criteria of ISO9000 and 4W's. Second, the questionnaires were discussed with two researchers knowledgeable in the field, and then submitted to the quality practitioners and executives of Iran Khodro Enterprise-a leading company in Iranian automotive manufacturing industry. Finally the null hypothesis was tested and the technology improvement dimensions were ranked through nonparametric tests. The results illustrated a reasonable cause and effect relationship, suggesting that ISO9000: 2000 has positive effect on the 4W's of company result. In this work we investigate the effect as technology improvement viz., the improvement of techno-ware, human-ware, info-ware, and organ-ware.

• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.79-84
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• 2011

There have been so many studies related to job stress or musculoskeletal disorders(MSDs) in the shipbuilding industry. However, study of employee performance evaluation that reflect on the industrial features of the deckhouse manufacturing industry has not been established. Therefore, this study aimed to evaluate workers' job stress and work ability through statistical significance tests according to age, work types, years of service, work forms and sex. For this, the study conducted a job stress test using the Korean Occupational Stress Questionnaire Short Form, and employee performance evaluations using the Work Ability Index(WAI) of the Finnish Institute of Occupational Health (FIOH) on 536 workers in the deckhouse manufacturing industry. MINITAB statistics program was used for statistics analysis and significance was verified with the Kruskal-Wallis test, a corporate body of nonparametric statistical analysis. As a result, employee performance had significant differences, depending on age, work types, years of service and sex, and job stress also depended on the number of service year and work form. Additionally, it was found that employee performance decreased more as job stress increased.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.28 no.1
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• pp.53-60
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• 2002

Neurosensory dysfunction of the injured inferior alveolarnerve(IAN) is a common and distrssing consequence of traumatic or iatrogenic injury. Conventional neurosensory testing has been used to detect and monitor sensory impairments of the injured IAN. However, these tests had low reliability and are not qualitative at best because they are based on solely on the patient's subjective assesment of symptoms. Consequently, there is need for more reliable, sensitive, and objective test measures to document and to monitor sensory dysfunction of the trigeminal nerve. This study was to investigate DITI's (digital infrared thermographic imaging) potential as a diagnostic alternative for evaluating of the nerve injures and sensory disturbance. Subjects were 30 patients who had been referred to Ewha Medical Center due to sensory disturbance of the lower lip and chin followed after unobserved inferior alveolar nerve injuries. The patients were examined by clinical neurosensory tests as SLTD (static light touch discrimination), MDD (moving direction discrimination), PPN (pin prick nociception) and DITI (digital infrared thermographic imaging). The correlation between clinical sensory dysfunction scores(Sum of SLTD, MDD, PPN, NP, Tinel sign) and DITI were tested by Spearman nonparametric rank correlation anaylsis & Kruskal-Wallis test, Wilcoxon 2-sample test. This study resulted in as follows; (1) The difference of thermal difference between normal side and affected side was as ${\Delta}-3.2{\pm}0.13$. (2) The DITI differences of the subjects presenting dysesthesia of the lip and chin were correlated significantly with the neurosensory dysfunction scores(r=0.419, p=0.021)and SLTD (r=0.429, p<0.05). (3) The MDD, PPN, NP, Tinel sign, duration, gender were not correlated with DITI(p> 0.05). Therefore, the DITI(digital infrared thermographic imaging) can be an option of the useful objective diagnostic methods to evaluate the injured inferior alveolar nerve and sensory dysfunction of trigerminal nerve.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.250-257
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• 2001

Sensory dysfunction following the injury of the inferior alveolar nerve requires objective examination to get a reproducible data and to provide necessary treatment. This study was designed to evaluate if the SEP(somatosensory evoked potentials) of the mental nerve can be used as an objective method for the diagnosis of nerve injury and sensory disturbances. The subjects were nineteen patients ($37.4{\pm}11.3$ years old) who had been suffered from sensory disturbance of the unilateral lower lip and mental region for over 6 months after the inferior alveolar nerve injuries confirmed by the microsurgical explorations. The clinical neurosensory tests as SLTD(static light touch discrimination), MDD(moving direction discrimination), 2PD(two point discrimination), PPN(pin prick nociception) and accompanied pain were preceded to electro-physiologic examinations as SEP. The score of sensory dysfunction (sum score of all sensory tests) ranged from 0 to 8 were compared to the latency differences of the mental nerve SEPs. The correlation between clinical sensory scores and SEPs were tested by Spearman nonparametric rank correlation analysis, the differences in SEP latency by Kruskal-Wallis test and the latency differences according to PPN and accompanied pain by Mann-Whitney U test. This study resulted that the difference of the latencies between normal side and affected side was $2.22{\pm}2.46$ msec and correlated significantly with the neurosensory dysfunction scores (p=0.0001). Conclusively, the somatosensory evoked potentials of the mental nerve can be a useful diagnostic method to evaluate the inferior alveolar nerve injuries and the change of sensory dysfunction to be reproduced as an objective assessment.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.31 no.1
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• pp.42-51
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• 2018

Objectives : This study was aimed to evaluate the correlation between changes in disease severity and serum total IgE or eosinophil count in individual patients of atopic dermatitis depending on the change of severity. Methods : We performed a retrospective chart review of 8 cases of atopic dermatitis who underwent blood tests more than five times. Disease severity was assessed by objective SCORing of Atopic Dermatitis index (OSI). Blood tests include serum total IgE, eosinophil counts, aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and serum creatinine (SCr). In each subject, on the day that the blood test was performed, OSI was also assesed by a same physician. Correlation between OSI and total IgE or eosinophil count was analysed by nonparametric correlation analysis. Results : There was a statistically significant positive correlation between OSI and total IgE in three cases and a positive correlation between OSI and eosinophil count in two cases. In other three cases, there were no significant correlation. There were no cases that OSI correlated with total IgE and eosinophil count at the same time. In all cases, AST, ALT, BUN and SCr were stable. Conclusions : We suggest that total IgE and eosinophil count may reflect the severity of atopic dermatitis differently in individual patients. We also suggest that total IgE and eosinophil counts may be used as biomarkers to predict the severity of atopic dermatitis in some patients depending on the underlying pathology.

• Journal of Information Science Theory and Practice
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• v.10 no.4
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• pp.66-86
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• 2022

The main aim of this study is to identify the role of information dissemination on urban and rural citizens of Bangladesh during the COVID-19 pandemic and the role of misinformation in this process. The study also aimed at finding appropriate counter misinformation strategies regarding COVID-19. An online questionnaire was prepared to collect the viewpoints of the urban and rural citizens of Bangladesh regarding dissemination of information during COVID-19, misinformation regarding COVID-19, and counter misinformation strategies. Along with demographic and general information, a five-point Likert scale was used to measure COVID-19 related misinformation beliefs and how to counter them. Chi square tests were used to determine the association between current residency, information sources, the importance of information dissemination, reactions after getting COVID related information, and evaluative steps after getting information and before disseminating it. Additionally, nonparametric Mann-Whitney U and Kruskal-Wallis tests were conducted to know the significance of difference in respondents' assessment on COVID-19 related misinformation in terms of their demographic characteristics. Cronbach's alpha score was obtained to see the reliability of the questionnaire items. The current study reveals that both urban and rural citizens of Bangladesh are influenced by information dissemination regarding COVID-19 and they have lower level of misinformation belief. The respondents have differences in misinformation belief by different demographic groups. Respondents' educational status, information literacy, sources of getting information, and evaluative steps after getting information have significant differences in misinformation belief. The study also noticed the support of respondents for countering misinformation strategies regarding COVID-19.