• Journal of the Korean earth science society
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• v.31 no.1
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• pp.95-105
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• 2010

The purpose of this study lies in applying generalizability theory depending on the aim of the usage of GALT to analyze the sources of error of single-facet considering item and person only and to analyze the sources of error of multi-facet considering item, person and domain. The study was conducted with 1016 students of local elementary, middle, and high schools. The 21 items of a full version were answered for 40 minute and then the 12 items of short version were sampled to analyze reliability using generalizability theory. Both the full version and the short version of the items were analyzed using Cronbach's alpha for data analysis, and we applied generalizability theory and separate $p{\times}i$ design and $p{\times}(i:h)$ design, G study and D study were performed. Results of analysis are as follows: First, the result of D study after $p{\times}I$ design both on the full version and the short version showed that in the case of the full version, the generalizability coefficient was 0.87 exceeding a normal level of 0.80, and the normal level of generalizability coefficient was achieved in 13 items as well. In case of short version, when 12 items were evaluated, generalizability coefficient was 0.77 not reaching the normal level, and the normal level was achieved in case of more than 15 items. Second, the result of D study after $p{\times}(I:H)$ design on the short version showed that once one domain consists of 2 items in 6 domains, generalizability coefficient was 0.71 which is lower than the normal level of 0.80, the normal level was achieved in more than 5 item cases.

• Science of Emotion and Sensibility
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• v.11 no.4
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• pp.553-564
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• 2008

Generalizability theory was employed to examine how the reliability of polygraph test is affected by the number of relevant questions, the number of repeated tests (the number of of charts), and the number of raters(scorers). The data consisted of the results of the polygraph tests administered to 31 crime suspects. The sample was drawn from the real polygraph tests based on Backster ZCT and archived by the Prosecutor's Office of the Republic of Korea. The numerical scores assigned by thirteen raters to the test charts were analyzed to determine the generalizability of the scores. The largest variance component was accounted for by the examinee factor(43.97%) and the residual variance component was 16.84% of the total variance. The variance component due to the interaction between the examinee and the chart factors was 12.17% and the variance component due to the three way interaction of the examinee, the repeated test, and the relevant question factors was 10.31%. The generalizability coefficient for the current measurement procedure as practiced by the Korean Prosecutor's Office was 0.74 which suggests that the current procedure is acceptable. However, measurement procedures with the combination of more than two relevant questions, more than three repeated tests, and more than two raters were generally found to yield generalizability coefficients larger than 0.80. Therefore, such procedures need to be considered seriously in order to significantly improve the reliability of polygraph test.

• Communications of Mathematical Education
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• v.28 no.4
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• pp.431-455
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• 2014

The purpose of this study was to suggest methods to apply generalizability theory to mathematics teacher evaluation using classroom observations in Korea by analysing mathematics teachers in the U.S. using the instructional quality of assessment instrument as an illustrative example. The subjects were 96 teachers participating in Year 3 and Year 4 from the Middle-school Mathematics and the Institutional Setting of Teaching (MIST) project funded by the National Science Foundation since 2007. The MIST project investigates the following question: What does it takes to support mathematics teachers' development of ambitious and equitable instructional practices on a large scale (MIST, 2007). This study examined data based on both the univariate generalizability analysis using GENOVA program and the multivariate generalizability analysis using mGENOVA program. Specifically, this study determined the relative effects of each error source and investigated optimal measuring conditions to obtain the suitable generalizability coefficients. The methodology applied in this study can be utilized to find effective optimal measurement conditions for the mathematics teacher evaluation for professional development in Korea. Finally, this study discussed limitations of the results and suggested directions for future research.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.691-693
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• 2002

일반화 다각형(generalized polygons)이란 선분과 호로 둘러싸인 $R^2$영역으로 정의되는 확장된 다각형 개념으로 로보틱스 등의 응용 분야에서 다루는 중요한 도형군이다. 로보틱스에 응용되는 컴퓨터 기하학 알고리즘의 대부분은 선분이나 다각형을 다루도록 개발되어 있어 로봇 작업환경의 다양한 물체들을 선분만으로 모델링해야만 알고리즘의 적용이 가능하다. 기존의 알고리즘들을 일반화 다각형을 다룰 수 있도록 확대한다면 보다 유연한 모델링을 가능하게 할 것이다. 주 논문에서는 컴퓨터 기하학분야의 대표적인 알고리즘인 plane-sweep 알고리즘을 일반화 다각형을 다룰 수 있도록 수정하고 구현한다. 이를 로보틱스이 응용분야중 하나인 고정쇠 문제(fixturing)에 적용한다.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.511-523
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• 2005

The purpose of this study is to analyze the 1st and 2nd Korea Earth Science Olympiad (KESO) items, in order to find informations to enhance item quality. To do this, internal and external item classification frameworks are developed. Item difficulty (P), discrimination index (DI), correlation, and reliability are estimated by using classical test theory. Generalizability is also estimated by applying the generalizability theory. The results of item classification are as follows: (1) ‘Geology’, ‘astronomy’ and ‘data analysis and interpretation’ are dominant in content and inquiry process domain, respectively. Nearly every item has textbook context. (2) There is no difference between the preliminary and final tests in terms of their thinking skills sections. (3) As a whole, the ratio of items with pictures is high in item representation. However, multiple-choice and short answer items are more common in preliminary competition, and essay type items are found more often in final competition. The ratio of simple items is high in middle school section and preliminary competition, but composite items are dominant in high school section and final competition. The findings of item analysis are as follows: (1) In the middle school section, P is low and DI is moderate. But in the high school section, there is a considerable differences between science high schools and other high schools in general. (2) The highest correlation is reported between the scores of meteorology domain and total score in middle school, whereas in high school astronomy domain and total score show the highest correlation. (3) General high school section show the highest Cronbach $\alpha$ and generalizability. (4) General high school section show acceptable generalizability coefficient (> 0.80), but middle and science high school section should increase the number of items to reach acceptable generalizability level.

• Proceedings of the Korean Statistical Society Conference
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• 2001.11a
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• pp.109-114
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• 2001

m=2 또는 n=2이고, ${\lambda}_1<{\lambda}_2$인 그룹분류가능계획을 매개디자인으로 사용한 완전이면교배가 A-최적, D-최적임을 보였다. 또한, ${\lambda}_2={\lambda}_1+1$이면 일반화된 최적계획이 됨을 보였다.

• The Korean Journal of Applied Statistics
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• v.30 no.1
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• pp.95-102
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• 2017

Gamma generalized linear models have received less attention than Poisson and binomial generalized linear models. Therefore, many old-established statistical techniques are still used in gamma generalized linear models. In particular, existing literature and textbooks still use approximate estimates for the dispersion parameter. In this paper we study the efficiency of various dispersion parameter estimators in gamma generalized linear models and perform numerical simulations. Numerical studies show that the maximum likelihood estimator and Cox-Reid adjusted maximum likelihood estimator are recommended and that approximate estimates should be avoided in practice.

• Journal of Gifted/Talented Education
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• v.23 no.5
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• pp.671-695
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• 2013

This study provides an illustrative example of using the multivariate generalizability theory. Specifically, it investigates relative effects of each error source, and finds optimal measurement conditions for the number of items within each content domain that maximizes the reliability-like coefficients, such as a generalizability coefficient and an index of dependability. The method is based on teacher recommendation letters and self-introduction letters, using an analytic scoring method in the context of selection of mathematically gifted students by observation and nomination. This study analyzed data from the 2011 academic year in the science education institute for the gifted, which is attached to the university located in the Seoul metropolitan area. It should be noted that the optimal scoring structures of this study are not generalizable to other selection instruments. However, the methodology applied in this study can be utilized to find optimal measurement conditions for the number of raters, the number of content domains, and the number of items in other selection instruments self-developed by many institutions including: the education institutes for the gifted at provincial offices of education, gifted classes, and the science education institutes for the gifted attached to universities in general. In addition, the methodology will provide bases for making informed decisions in selection instruments of the gifted based on measurement traits.

• Journal of The Korean Association For Science Education
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• v.25 no.2
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• pp.173-183
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• 2005

In this study, we questioned what assessment types and scoring methods of science performance assessment(SPA) were being used in middle and high school, and how much these SPA scores were reliable(generalizable). To answer these questions, SPA data obtained from the seven schools were classified according to assessment type and scoring method. Based upon this classification, we analyzed the reliability by applying generalizability theory. The result, from the classification of assessment type and scoring method, showed that SPA types of the seven schools were divided into two types: paper-pencil type and task type. Paper-pencil type included answer(content)-restricted essay-type test solely. Task type has two parts: process and outcome assessment. As the results of analyzing scoring methods of the seven schools, there were two cases in the way of scoring methods: one case is scoring all essay-type items and performance tasks by one teacher, the other is scoring assigned performance tasks by two teachers. But the case of scoring assigned essay-type items or the case of cross scoring by two or more teachers were not found. The findings of the reliability analysis are as follows: (1) Effect of essay-type item to SPA score was larger than that of performance task. (2) There was remarkable difference among the seven schools' interaction effect of person and rater in scoring performance tasks. (3) Most of generalizability(reliability) coefficients of SPA for the seven schools were smaller than the acceptable generalizability coefficient(0.80). Therefore, the population of statistical parameters such as number of item, task and rater, should be increased for approaching the acceptable generalizability level.

• The Korean Journal of Applied Statistics
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• v.31 no.4
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• pp.475-484
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• 2018

Gamma generalized linear models are useful for non-negative and skewed responses. However, these models have received less attention than Poisson and binomial generalized linear models. In particular, hypothesis testing for the significance of regression coefficients has not been thoroughly studied. In this paper we assess the performance of various test statistics for gamma generalized linear models based on numerical studies. Our results show that the likelihood ratio test and F-type test are generally recommended and that the partial deviance test should be avoided in practice.