• Journal of the Korean Data and Information Science Society
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• v.16 no.2
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• pp.227-236
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• 2005

A chi-squared test of spherical symmetry is suggested. This test is easy to apply in practice since it is easy to compute and has a limiting chi-squared distribution under spherical symmetry. The result of Park(1998) can be used to show that it has the limiting chi-squared distribution. A simulation study is conducted to study the accuracy, in finite samples, of the limiting distribution. Finally, a simulation study that compares the power of our test with those of other tests of spherical symmetry is performed.

• Journal of the Korean Data and Information Science Society
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• v.15 no.1
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• pp.83-94
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• 2004

In this study we analyze categorical data by means of spatial statistics and echelon analysis. To do this, we first determine the hierarchical structure of a given contingency table by using echelon dendrogram then, we detect candidates of hotspots given as the top echelon in the dendrogram. Next, we evaluate spatial scan statistics for the zones of significantly high or low rates based on the likelihood ratio. Finally, we detect hotspots of any size and shape based on spatial scan statistics.

• Communications for Statistical Applications and Methods
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• v.12 no.2
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• pp.521-529
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• 2005

In this paper, we consider a bootstrap method to the 'row and column effects model' (RC model) to analyze a contingency table with ordered variables. We propose a bootstrap procedure for testing of independence, equality of intervals, and goodness of fit in the RC model. A real data example is included.

• Communications for Statistical Applications and Methods
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• v.10 no.2
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• pp.479-496
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• 2003

We investigate logit confidence intervals for the odds ratio based on the delta method. These intervals are constructed using pseudo-Bayes estimators. The Gart method and Agresti method smooth the observed counts toward the model of equiprobability and independence, respectively. We obtain better coverage probability by smoothing the observed counts toward the pseudo-Bayes estimators in 2$\times$2 table. We also improve legit confidence intervals in 2$\times$2$\times$K tables by generalizing these ideas. Utilizing pseudo-Bayes estimators, we obtain better coverage probability by smoothing the observed counts toward the conditional independence model, no three-factor interaction model and saturated model in 2$\times$2$\times$K tables.

• Journal of Preventive Medicine and Public Health
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• v.32 no.2
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• pp.215-227
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• 1999

Objectives: To investigate compliance of hypertension patients using modified Theory of Reasoned Action(TRA). Methods: The data were collected for 7-12 April 1997, by interviewing 190 Hypertension patients in Hwachon, Kangwon-do. The analytical techniques employed include contingency table analysis and logit analysis. Results: 15.1% of patients were unaware of the fact that he/she has hypertension and 11.2% did not know that he/she should take drug. 20.8% of patients took drug continuously, 20.1% had drug intermittently, and 53.1% had never have treatment. In the contingency table analysis, several variables were found to be significantly related to patient compliance. They included variables for attitude towards the consequences of taking drugs, normative beliefs, systolic BP at the enrollment, knowledge of how to take hypertensive drugs, variables for general health behavior and experience with having health worker's home visit. The logit analysis was performed by two steps. first step uses experience with drug treatment of hypertension as the dependent variable, and second step uses continuity of treatment. Included in the predictors that are significantly related to the former analysis are subjected norms produced by combining normative beliefs and motivation to comply, knowledge of how to take hypertensive drugs, and opinion about natural recovery of diseases. The only significant determinant of continuous treatment was knowledge of how to take hypertensive drugs. Conclusions: The results of analysis suggest the usefulness of TRA as a framework for the study of compliance of hypertensive patients. The findings have some practical implication as well. One is that efforts for enhancing compliance should be directed not only patients but also to other persons influencing patient's attitude and behavior. It also suggest that correct understanding of hypertension treatment is essential to perform the appropriate patient role.

• Journal of the Korean Data and Information Science Society
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• v.10 no.2
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• pp.457-464
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• 1999

In this paper, we propose an overlapped mosaic plot which proposed by Hartigan and Kleiner(1981) represents the counts in $2{\times}2$ contingency table directly by tiles whose area is proportional to the cell frequency. Overlapped mosaic plot provides some measurements of association including dynamic graphics for mosaic plots. Dynamic graphics for mosaic plots give some useful informations when one gets some measurements of association and selects a model, and current statistical software does not provide this feature. We can see the deviations between observation and estimate of independence from overlapped mosaic plot. This dynamic graphics give some useful informations how far this data are apart from independence.

• Restorative Dentistry and Endodontics
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• v.36 no.2
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• pp.114-118
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• 2011

Objectives: This study was aimed to examine the patients' perception and satisfaction with the results of endodontic microsurgery which was apicoectomy with retrofilling. Materials and Methods: A questionnaire was given to 109 patients, who were recalled after a minimum of 3 months upon endodontic microsurgery in the Department of Conservative Dentistry, Yonsei University. A contingency table and correlation analysis were used to determine if there were any correlations between age/gender and the patients' responses (p = 0.05). Results: Approximately 60% of respondents answered they had never heard of surgical endodontic procedures. 63.3% of respondents chose the surgical option because they wanted to keep their natural teeth. If the patient required the same procedure on another tooth later, 100 out of 109 respondents answered they would choose microsurgery instead of extraction. Most patients (82.57%) appeared to be satisfied with the surgical procedure. Conclusions: Endodontic microsurgery consisting of apicoectomy and retrofilling seems to appeal to majority of patients as a satisfactory and valuable treatment choice.

• Korean Journal of Veterinary Research
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• v.36 no.4
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• pp.941-948
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• 1996

The accuracy of rectal palpation and ultrasonography for predicting the presence of a functional corpus luteum in subestrous dairy cows was investigated, using the result of a radioimmunoassay for progesterone in plasma. Luteal status (high or low progesterone concentrations) was diagnosed in 820 cows, using rectal palpation and B-mode transrectal ultrasonography, and the results of rectal palpation and ultrasonography were compared in $2{\times}2$ contingency table with plasma progesterone concentrations. A $2{\times}2$ contingency table analysis allowed the calculation of sensitivity, specificity and predictive values for rectal palpation and ultrasonography. The sensitivity, specificity, predictive value of a positive test and predictive value of a negative test were 81.9%, 67.5%, 79.0% and 71.4% for rectal palpation, and 96.3%, 88.8%, 94.5% and 92.4% for ultrasonography, respectively. The percentages of observed agreement and expected agreement between rectal palpation and ultrasonography were 71.8% and 57.1%, respectively. An evaluation of agreement between rectal palpation and ultrasonography, the value of Kappa was 0.34. It was concluded that a ultrasonography was more sensitive and specific than rectal palpation in predicting the presence of a functional corpus luteum. Therefore, ultrasonographic examination is a reliable method for assessing the functional status of ovarian structures in subestrous dairy cows.

• Asia pacific journal of information systems
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• v.18 no.2
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• pp.95-114
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• 2008

Recent interests in data mining result from the expansion of the amount of business data and the growing business needs for extracting valuable knowledge from the data and then utilizing it for decision making process. In particular, recent advances in association rule mining techniques enable us to acquire knowledge concerning sales patterns among individual items from the voluminous transactional data. Certainly, one of the major purposes of association rule mining is to utilize acquired knowledge in providing marketing strategies such as cross-selling, sales promotion, and shelf-space allocation. In spite of the potential applicability of association rule mining, unfortunately, it is not often the case that the marketing mix acquired from data mining leads to the realized profit. The main difficulty of mining-based profit realization can be found in the fact that tremendous numbers of patterns are discovered by the association rule mining. Due to the many patterns, data mining experts should perform additional mining of the results of initial mining in order to extract only actionable and profitable knowledge, which exhausts much time and costs. In the literature, a number of interestingness measures have been devised for estimating discovered patterns. Most of the measures can be directly calculated from what is known as a contingency table, which summarizes the sales frequencies of exclusive items or itemsets. A contingency table can provide brief insights into the relationship between two or more itemsets of concern. However, it is important to note that some useful information concerning sales transactions may be lost when a contingency table is constructed. For instance, information regarding the size of each market basket(i.e., the number of items in each transaction) cannot be described in a contingency table. It is natural that a larger basket has a tendency to consist of more sales patterns. Therefore, if two itemsets are sold together in a very large basket, it can be expected that the basket contains two or more patterns and that the two itemsets belong to mutually different patterns. Therefore, we should classify frequent itemset into two categories, inter-pattern co-occurrence and intra-pattern co-occurrence, and investigate the effect of the market basket size on the two categories. This notion implies that any interestingness measures for association rules should consider not only the total frequency of target itemsets but also the size of each basket. There have been many attempts on analyzing various interestingness measures in the literature. Most of them have conducted qualitative comparison among various measures. The studies proposed desirable properties of interestingness measures and then surveyed how many properties are obeyed by each measure. However, relatively few attentions have been made on evaluating how well the patterns discovered by each measure are regarded to be valuable in the real world. In this paper, attempts are made to propose two notions regarding association rule measures. First, a quantitative criterion for estimating accuracy of association rule measures is presented. According to this criterion, a measure can be considered to be accurate if it assigns high scores to meaningful patterns that actually exist and low scores to arbitrary patterns that co-occur by coincidence. Next, complementary measures are presented to improve the accuracy of traditional association rule measures. By adopting the factor of market basket size, the devised measures attempt to discriminate the co-occurrence of itemsets in a small basket from another co-occurrence in a large basket. Intensive computer simulations under various workloads were performed in order to analyze the accuracy of various interestingness measures including traditional measures and the proposed measures.

• 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.