• School Mathematics
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• v.14 no.4
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• pp.495-516
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• 2012

This study distinguished thinking related to statistical variability into six components - the noticing of variability, the explanation of variability, the control of variability, the modeling of variability, the understanding of samples, and the understanding of sampling distribution and investigated the relationships among the thinking components. This study found that this distinction of thinking components related to statistical variability is reasonable. The results showed that each correlation coefficient of the modeling of variability, the understanding of samples, and the understanding of sampling distribution with regard to the noticing of variability, the explanation of variability, and the control of variability is similar. Based on this results, new variable, the understanding of sampling, has been drawn. The results also showed that while the noticing of variability and the control of variability influence the understanding of sampling, the explanation of variability does not influence it.

• Journal of Educational Research in Mathematics
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• v.20 no.4
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• pp.493-509
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• 2010

Researchers have suggested that educators have to focus their attention on variability and reasoning about variation as means of developing students' statistical thinking in school mathematics. This paper investigated knowledge for the teaching of variability and reasoning about variation; what are sources of variability, how to cope with variability, what are types of variability, how to recognize variability, and the relationship between statistical problem solving and variability. The results involve: discussion on the sources of variability and how to cope with variability promotes students' awareness of different types of variability and students' motivation in the following steps in the statistical activity; emphasis on reasoning about variation in teaching representation of data accords with objectives of statistics education; reexamination of curriculum for statistics education is needed, which has a content-oriented arrangement.

• Journal of Educational Research in Mathematics
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• v.21 no.2
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• pp.201-220
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• 2011

This study investigates levels of thinking of elementary and middle school students doing their tasks of explaining and dealing with variability. According to results, on the task of explaining variability in the measurement settings five levels of thinking were identified: a lack of understanding of explanation of the causes, an insufficient understanding of the causes, an offer of physical causes, consideration of unexplained causes as the source of variability, and consideration of unexplained causes as quasi-chance variability. Also, in the chance settings five levels of thinking were identified: a lack of understanding of explanation of the causes, an insufficient understanding of the causes, an offer of physical causes, recognition of chance variability, and consideration of causes of distribution. On the task of dealing with variability in both the measurement and chance settings five levels of thinking were identified: a lack of understanding of dealing with variability, no physical control and improper statistical control, no physical control and proper statistical control, physical control and improper statistical control, and physical control and proper statistical control.

• Korean Journal of Construction Engineering and Management
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• v.2 no.4 s.8
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• pp.117-126
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• 2001

The purpose of this study is to present a way of Variation Control in building construction process. The study suggest a way of the application method of shielding, decoupling concept and also Poka-yoke device to control variation that occurs from uncertainty in construction industry with lots of waste factors. The main contents of the study are as follows; (1) It's suggested strategy to apply shielding, decoupling as variation control technique. (2) Current Poka-yoke devices are investigated and analyzed. As a future research, it is required to study continuously on the more effective application method of Poka-yoke device and on existing examples in domestic construction sites for the process improvement.

• School Mathematics
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• v.9 no.1
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• pp.29-44
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• 2007

The aim of statistics education is to enhance statistical thinking. Variability is the key components of statistical thinking. The research has been reviewed preceding research about variability of data. Proceeding from what has been considered above, this research developed learning materials that investigated the concept of variability as it relates to Freudenthal's context by having students sort a particular context. The research is executed the case study evidently aimed at Junior High School 3rd Grade Student's Understanding of Variability. The study of variability in data can be an important start to reach a testing of statistical hypothesis; students reduce data and draw graphs by relating probability distribution to relative frequency and normal distribution. Thus, this study offers basic materials into developing both contents and methods of education need to consider with this sense of purpose held by students to achieve this goal.

• Journal of Educational Research in Mathematics
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• v.20 no.3
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• pp.339-356
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• 2010

It is important for children to develop statistical reasoning as they think through data. In particular, it is imperative to provide children instructional situations in which they are encouraged to consider variability in data because the ability to reason about variability is fundamental to the development of statistical reasoning. Many researchers argue that even highperforming mathematics students show low levels of statistical reasoning; interventions attending to pedagogical concerns about child ren's statistical reasoning are, thus, necessary. The purpose of this study was to investigate 15 gifted elementary students' various ways of understanding important statistical concepts, with particular attention given to 3 students' reasoning about data that emerged as they engaged in the process of generating and graphing data. Analysis revealed that in recognizing variability in a context involving data, mathematically gifted students did not show any difference from previous results with general students. The authors suggest that our current statistics education may not help elementary students understand variability in their development of statistical reasoning.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.234-239
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• 2021

The purpose of this paper is to find out the nature of language variation by exploring the ways of the progress of the language variation that produces all English-lects, i.e., the World Englishes. The study of language variation in linguistics is a hybrid enterprise, so the study of World Englishes has led to the recognition of a highly diverse set of all English-lects, encompassing regional dialects, sociolects, ethnolects and (post-)colonial dialects of World Englishes. In this paper, we propose a hybrid language variation model with three interacting factors of social distancing, on/off-contact, and linguistic diversity to examine the characteristics of language variation. In the context of World Englishes, the social distance is typically low in terms of their local location (country/speech) for local purposes. The social distance also varies based on online/offline communication modes and other social factors like gender, age and ethnic groups, resulting in all English-lects. To clarify the nature of World Englishes, the core Englishes, BrE, AmE and CanE are discussed here.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.06a
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• pp.455-460
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• 2008

본 연구에서는 1997년 1월부터 2006년 12월까지의 기상청에서 제공하는 31개 자동기상관측망(AWS: Automatic Weather Stations)에 의한 지표 근처 기온($^{\circ}C$) 및 강수(mm) 자료를 이용하여 서울 지역 기상인자의 시 공간 구조 분석 및 변화경향과 변이성을 도출하였다. 미관측지점의 값을 추정하기 위하여 주변 관측지점들을 고려하여, 그 영향은 거리에 반비례함을 반영하는 공간통계학적 방법 중 IDSW(Inverse Distance Squared Weighing:거리자승역산가중)를 적용하여 보관하였다. 그 결과 서울시의 기온과 강수량 모두 1997년에 비해 2006년의 기온이 약 $1.03^{\circ}C$, 강수량이 약 483mm 증가한 것으로 나타났다. 기후변이성의 특성은 과거 10년 동안 기온의 경우 산림지역에서는 변화의 폭이 높게 나타났으며, 시간이 지나면서 감소하는 경향을 보였다. 주거 지역의 경우 변화이 폭이 낮게 나타났으며, 시간이 지나면서 증가하는 경향을 보였다. 그러나 강수량의 경우 산림지역과 주거지역의 변이성의 차이가 나타나지 않았다.

• Journal of Educational Research in Mathematics
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• v.16 no.3
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• pp.221-249
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• 2006

The object of this study is to understand the characteristics of mathematical knowledge that elementary 5th graders have regarding the statistical variation concept and the changes after taking lessons. This study includes a pretest to examine the characteristics of mathematical knowledge that elementary 5th graders have regarding the statistical variation concept. And It was followed by a lesson on statistical variation concept to be able to correct error which was revealed by the inspection, and to improve good points. It turned out that after five lessons on the statistical variation concept, the insufficient aspects were properly improved, and as for the points they already understand, they came to understand better than before. They came to consider the statical variation concept instead of the frequency, preponderance, average, stable traits for the optimum value. Also, through the lesson on drawing tables and graphs, they came to better understand them, analyzing correctly the exercises in which tables and graphs were combined. When comparing data sets whose general distributions and extents were similar, students came up with the right answers in a stable way by considering averages combining statistical variation too. Since they tended to interpret a situation with their own subjective views adding conditions, teachers need to examine the proper situation and conditions prior to the lessons on the statistical variation concept.

• Asian Journal of Turfgrass Science
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• v.15 no.3
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• pp.127-136
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• 2001

A field trial was initiated to examine the range of inter- and intraspecific variations in morphological and phenological traits with five different accessions of smooth and large crabgrass. In addition, a controlled environment study was conducted to determine the phenotypic plasticity among the accessions of both species in response to 4 daily tempera-ture differentials. In the field experiment, significant inter- and intraspecific variations of smooth and large crabgrass were observed in morphological traits such as leaf length and width. However, most phenological traits were not substantially different between the species and among the accessions of each species. The first seedling emerged at the same time, requiring 9~ 10 days, regardless of the accessions and species. In a controlled environment study, all accessions of each species responded similarly to the 4 temperature differentials in seedling emergence, indicating seedling emergence was not a plastic trait. These results suggest that predicting crabgrass seedling emergence could be independent of geographical regions in the US.