• The Korean Journal of Applied Statistics
• /
• v.14 no.1
• /
• pp.39-57
• /
• 2001

Categorical data has sometimes misclassification errors. If this data will be analyzed, then estimated cell probabilities could be biased and the standard Pearson X2 tests may have inflated true type I error rates. On the other hand, if we regard wellclassified data with misclassified one, then we might spend lots of cost and time on adjustment of misclassification. It is a necessary and important step to ask whether categorical data is misclassified before analyzing data. In this paper, when data is misclassified at one of two variables for two-dimensional contingency table and marginal sums of a well-classified variable are fixed. We explore to partition marginal sums into each cells via the concepts of Bound and Collapse of Sebastiani and Ramoni (1997). The double sampling scheme (Tenenbein 1970) is used to obtain informations of misclassification. We propose test statistics in order to solve misclassification problems and examine behaviors of the statistics by simulation studies.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.16 no.4
• /
• pp.379-388
• /
• 1983

The subtidal benthic algal communities of Dolsan-island in the southern coast of Korea were surveyed by means of SCUBA diving. The vertical zonation is recognized into three groups; upper, middle and lower subtidal zones. The representative species in each group throughout the year are Ulva pertusa, Codium fragile, Chondria crassicaulis and Gigartina tenera in the upper, Myagropsis myagroides and Sargassum tortile in the middle, and Plocamium telfairiae, Callophyllis japonica and Symphyocladia linearis in the lower zone. According to the normal association analysis by $2{\times}2$ contingency table and chi-square calculation among 29 quadrats, the algal communities are divided into 9 groups which are dominated by Sargassum tortile, Myagropsis myagroides, Chondria crassicaulis, Codium fragile, Pterocladia tenuis, Gigartina tenera, Gracilaria textorii. The thallus length and standing crops of Myagropsis myagroides show the highest value in spring and the lowest in summer.

• 한국사회복지학회:학술대회논문집
• /
• 2004.10a
• /
• pp.461-492
• /
• 2004

This study examined the effects of gender, parental support and treatment type on the treatment outcome of adolescent substance abusers. Outcome variable was the successful graduation (or drop) from an Intensive Adolescent Outpatient Program. Adolescents with their parents' support were treated in one of three treatment models (2-weeks Inpatient plus 6 week Intensive Croup-Oriented Outpatient, 8-weeks Intensive Croup-Oriented Outpatient, and 8-weeks Individual-Family Therapy) within a private hospital-affiliated treatment center by managed care practice allowing their own choice (non-random natural assignments). Several hypotheses were tested for main effects by the Log-Linear Analyses for a multi-dimensional contingency table with 440 adolescents (284 boys and 156 girls treated during 1992-l997) from middle-class families with private health insurances. The following results were found. Odds of graduating versus dropping out of the treatment program among : (1) girls were 1.7 times higher than those among boys; (2) adolescents with two-parent were 2.2 times higher than those among adolescents with one-parent ; (3) adolescents with Inpatient plus Outpatient was 1.7 times higher than that of those with Outpatient; (4) adolescents with Individual-Family Therapy was 2.3 times higher than that of those with Outpatient Model. There was no statistically significant outcome difference between the Individual-Family Therapy and the Inpatient plus Outpatient. Implications from the results were discussed. Suggestions were made to improve the treatment components in the areas of gender sensitivity, securing more parental support, alternatives for separation from peer group and integrating new peer groups, and flexibility for the unique needs of individual family. Also, some research questions for future studies were suggested.

• Journal of Trauma and Injury
• /
• v.20 no.2
• /
• pp.106-114
• /
• 2007

Purpose: There is little controversy that a classic indication such as hemodynamic instability or any sign of peritoneal irritation requires an immediate laparotomy in the management of abdominal stab wounds. However, omental herniation or bowel evisceration as an indication for an immediate laparotomy is controversial. The purpose of this study was to evaluate the significance of these factors as indications for an immediate laparotomy. Methods: The medical records of 98 consecutive abdominal stab wounds patients admitted to the Emergency Center of Masan Samsung Hospital from January 2000 to December 2006 were carefully examined retrospectively. Using multivariate logistic regression analysis, thirty-nine factors, including the classic indication and intraabdominal organ evisceration, were evaluated and were found to be associated with a need for a laparotomy. Also, the classic indication was compared with a new indication consisting of components of the classic indication and intra-abdominal organ evisceration by constructing a contingency table according to the need for a laparotomy. Results: Multivariate logistic regression analysis revealed any sign of peritoneal irritation, base deficit, and age to be significant factors associated with the need for a laparotomy (p<0.05). The sensitivity, specificity, and accuracy rates of the classic indication were 98.6%, 72.0%, and 91.8%, respectively, and those of the new indication were 93.2%, 84.0%, and 90.8%, respectively. The differences in those rates between the above two indications were not significant. Conclusion: Intra-abdominal organ evisceration was not a significant factor for an immediate laparotomy. Moreover, the new indication including intra-abdominal organ evisceration was not superior to the classic indication. Therefore, in the management of abdominal stab wounds, the authors suggest that an immediate laparotomy should be performed on patients with hemodynamic instability or with any sign of peritoneal irritation.

• Journal of The Korean Astronomical Society
• /
• v.40 no.4
• /
• pp.99-106
• /
• 2007

Statistical analyses were performed to investigate the relative success and accuracy of daily maximum X-ray flux (MXF) predictions, using both multilinear regression and autoregressive time-series prediction methods. As input data for this work, we used 14 solar activity parameters recorded over the prior 2 year period (1989-1990) during the solar maximum of cycle 22. We applied the multilinear regression method to the following three groups: all 14 variables (G1), the 2 so-called 'cause' variables (sunspot complexity and sunspot group area) showing the highest correlations with MXF (G2), and the 2 'effect' variables (previous day MXF and the number of flares stronger than C4 class) showing the highest correlations with MXF (G3). For the advanced three days forecast, we applied the autoregressive timeseries method to the MXF data (GT). We compared the statistical results of these groups for 1991 data, using several statistical measures obtained from a $2{\times}2$ contingency table for forecasted versus observed events. As a result, we found that the statistical results of G1 and G3 are nearly the same each other and the 'effect' variables (G3) are more reliable predictors than the 'cause' variables. It is also found that while the statistical results of GT are a little worse than those of G1 for relatively weak flares, they are comparable to each other for strong flares. In general, all statistical measures show good predictions from all groups, provided that the flares are weaker than about M5 class; stronger flares rapidly become difficult to predict well, which is probably due to statistical inaccuracies arising from their rarity. Our statistical results of all flares except for the X-class flares were confirmed by Yates' $X^2$ statistical significance tests, at the 99% confidence level. Based on our model testing, we recommend a practical strategy for solar X-ray flare predictions.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.8
• /
• pp.4717-4721
• /
• 2013

Complete surgical resection of the primary tumour is a crucial predictive step for head and neck squamous cell carcinoma (HNSCC), because incomplete resection may lead to increase in the recurrence rate. Molecular cancer markers have been investigated as potential predictors of prognosis marker, to identify patients who are at high risk of local recurrence. This retrospective study aimed to determine the prognostic correlation between p53 and eIF4E expression and clinical characteristics, recurrence and overall survival. Forty eight HNSCC patients were selected between 2006 and 2009 diagnosed at the Royal Darwin Hospital, Darwin, Northern Territory, Australia. Out of 48, only those 24 with negative surgical margins with hematoxylin and eosin (HandE) were chosedn for further analysis. A total of 77 surgical margins were obtained and subsequently analysed by immunohistochemical (IHC) staining with monoclonal p53 and polyclonal eIF4E antibodies. Contingency table and ${\chi}^2$-test were used to investigate the correlation between p53 and eIF4E expression and clinical characteristics, recurrence and overall survival of the HNSCC patients. The follow up period was 74 months (range 1-74 months). The Kaplan-Meier method was used to generate recurrence and survival curves. This is a first retrospective study of Northern Territory patients, including Indigenous and non-Indigenous Australians. Molecular study of surgical margins could help to identify patients with and without clear margins after surgery and help in choice of the most appropriate adjuvant treatment for HNSCC patients.

• Journal of Preventive Medicine and Public Health
• /
• v.37 no.4
• /
• pp.366-372
• /
• 2004

Objectives : This study was conducted to propose a new transmission/disequilibrium test(TDT) to test the linkage between genetic markers and disease-susceptibility genes based on haplotypes. Simulation studies were performed to compare the proposed method with that of Zhao et al. in terms of type I error probability and powers. Methods : We estimated the haplotype frequencies using the expectation-maximization(EM) algorithm with parents genotypes taken from a trio dataset, and then constructed a two-way contingency table containing estimated frequencies to all possible pairs of parents haplotypes. We proposed a score test based on differences between column marginals and their corresponding row marginals. The test also involved a covariance structure of marginal differences and their variances. In simulation, we considered a coalescent model with three genetic markers of biallele to investigate the performance of the proposed test under six different configurations. Results : The haplotype-based TDT statistics, our test and Zhao et al.'s test satisfied a type I error probability, but the TDT test based on single locus showed a conservative trend. As expected, the tests based on haplotypes also had better powers than those based on single locus. Our test and that of Zhao et al. were comparable in powers. Conclusion : We proposed a TDT statistic based on haplotypes and showed through simulations that our test was more powerful than the single locus-based test. We will extend our method to multiplex data with affected and/or unaffected sibling(s) or simplex data having only one parent s genotype.

• The Plant Pathology Journal
• /
• v.36 no.1
• /
• pp.54-66
• /
• 2020

This study was conducted to evaluate usefulness of numerical weather prediction data generated by the Unified Model (UM) for plant disease forecast. Using the UM06- and UM18-predicted weather data, which were released at 0600 and 1800 Universal Time Coordinated (UTC), respectively, by the Korea Meteorological Administration (KMA), disease forecast on bacterial grain rot (BGR) of rice was examined as compared with the model output based on the automated weather stations (AWS)-observed weather data. We analyzed performance of BGRcast based on the UM-predicted and the AWS-observed daily minimum temperature and average relative humidity in 2014 and 2015 from 29 locations representing major rice growing areas in Korea using regression analysis and two-way contingency table analysis. Temporal changes in weather conduciveness at two locations in 2014 were also analyzed with regard to daily weather conduciveness (C_i) and the 20-day and 7-day moving averages of C_i for the inoculum build-up phase (C_inc) prior to the panicle emergence of rice plants and the infection phase (C_inf) during the heading stage of rice plants, respectively. Based on C_inc and C_inf, we were able to obtain the same disease warnings at all locations regardless of the sources of weather data. In conclusion, the numerical weather prediction data from KMA could be reliable to apply as input data for plant disease forecast models. Weather prediction data would facilitate applications of weather-driven disease models for better disease management. Crop growers would have better options for disease control including both protective and curative measures when weather prediction data are used for disease warning.

• Tunnel and Underground Space
• /
• v.18 no.3
• /
• pp.185-193
• /
• 2008

We have carried out Pearson-type chi-square tests on the orientation data of joints from different depths in order to estimate the homogeneity of joint orientations obtained from a borehole. The orientation data of joints were collected from two non-foliated massive rocks of granitic gneisses in South Korea since orientations of joints in folded metamorphic rocks, for example, are controlled by foliation and also changes as the orientations of foliation change by folding. Borehole images were used for the analysis of the orientations of individual joints. The orientation data were subdivided into the upper level data and lower level data. The data from these two levels are plotted on the patch net consisting of 21 orientation patches. Then, the two patterns on the patch net were analyzed using a contingency table. From the chi-square test on the data collected from two sites, we found that some data sets show statistically meaningful differences in orientations of joints. Since joints are one of the important parameters in determining the physical properties of rock masses, in situ investigation of joints are desirable in the geotechnical investigation and also in design of subsurface structures (e.g. tunnels and underground storages).

• Journal of the Korean Data and Information Science Society
• /
• v.21 no.6
• /
• pp.1081-1090
• /
• 2010

Most nations including Korean government make a great endeavor to realize low-carbon and green-growth world. We also work hard to expand bicycle facilities and bicycle road in order to increase bicycle transportation rate. Nowadays number of cyclists is increasing but fortunately, bicycle accidents also increase rapidly. Most data of bicycle accidents published by National Police Agency annually are represented as frequencies in two dimensional contingency tables. In this work, risk rates and characteristics of bicycle accidents are analyzed by using concepts of the probability and conditional probability. Especially with numbers of estimated cyclists and registered cars, risk rates of various kinds of bicycle accidents are obtained. Under the assumption of the conditional independence, probability of bicycle accident occurred at realistic situations could be estimated. Furthermore we discuss to reduce bicycle accidents with these results obtained in this work.