• Title/Summary/Keyword: spatial statistics

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Power Comparison of Independence Test for the Farlie-Gumbel-Morgenstern Family

  • Amini, M.;Jabbari, H.;Mohtashami Borzadaran, G.R.;Azadbakhsh, M.
    • Communications for Statistical Applications and Methods
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    • v.17 no.4
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    • pp.493-505
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    • 2010
  • Developing a test for independence of random variables X and Y against the alternative has an important role in statistical inference. Kochar and Gupta (1987) proposed a class of tests in view of Block and Basu (1974) model and compared the powers for sample sizes n = 8, 12. In this paper, we evaluate Kochar and Gupta (1987) class of tests for testing independence against quadrant dependence in absolutely continuous bivariate Farlie-Gambel-Morgenstern distribution, via a simulation study for sample sizes n = 6, 8, 10, 12, 16 and 20. Furthermore, we compare the power of the tests with that proposed by G$\ddot{u}$uven and Kotz (2008) based on the asymptotic distribution of the test statistics.

K-function Test for he Spatial Randomness among the Earthquakes in the Korean Peninsula

  • Baek, Jangsung;Bae, Jong-Sung
    • Communications for Statistical Applications and Methods
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    • v.8 no.2
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    • pp.499-505
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    • 2001
  • Kim and Baek (2000) tested the spatial randomness for he earthquake occurrence in the Korean Peninsula by using the nearest-neighbor test statistics and empirical distribution functions. The K-function, however, has obvious advantages over the methods used in Kim and Baek (2000), such as it does not depend on the shape of the study region and is an effective summary of spatial dependence over a wide range of scales. We applied the K-function method for testing the randomness to both of the historical and the instrumental seismicity data. It was found that he earthquake occurrences for historical and instrumental seismicity data are not random and clustered rather than scattered.

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SPATIAL TRENDS AND SPATIAL EXTREMES IN SOUTH KOREAN OZONE

  • Yun, Seok-Hoon;Richard L. Smith
    • Journal of the Korean Statistical Society
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    • v.32 no.4
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    • pp.313-335
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    • 2003
  • Hourly ozone data are available for 73 stations in South Korea from January, 1988 to August, 1998. We are interested in detecting trends in both the mean levels and the extremes of ozone, and in determining how these trends vary over the country. The latter aspect means that we also have to understand the spatial dependence of ozone. In this connection, therefore, we examine in this paper the following features: determining trends in mean ozone levels at individual stations and combination across stations; determining trends in extreme ozone levels at individual stations and combination across stations; spatial modeling of trends in mean and extreme ozone levels.

Geo-statistical Analysis of Growth Variability in Rice Paddy Field (벼 재배 포장 생육변이의 공간통계학적 해석)

  • 이충근;성제훈;정인규;김상철;박우풍;이용범;박원규
    • Journal of Biosystems Engineering
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    • v.29 no.2
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    • pp.109-120
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    • 2004
  • To obtain basic information for precision agriculture, spatial variability of rice growth condition was evaluated in 100m ${\times}$100m paddy field. The rice growth condition of four hundred locations in the field were investigated to analyze the spatial variability of their properties ; SPAD, plant length and tiller number. Geostatistical analysis was carried out to examine within-field spatial variability using semivariograms and kriged maps as well as descriptive statistics. Descriptive statistics showed that the coefficient of variation for SPAD, plant length, and tiller number exceeded 5.70 %, suggesting a relatively high variability. Geostatistical analysis indicated a high spatial dependence for all the properties except for the second tiller number. The range of spatial dependence was about 20 m for SPAD, plant length, and tiller number. Based on the results of spatial dependence, kriged maps were prepared for the properties to analyse their spatial distribution in the field. The results reflected the history of field management. In conclusion, the need for site-specific field management and possibility of precision agriculture were demonstrated even in an almost flat paddy field.

Estimation of Spatial Dependence with GEE

  • Lee, Yoon-Dong;Choi, Hye-Mi
    • Proceedings of the Korean Statistical Society Conference
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    • 2003.05a
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    • pp.269-273
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    • 2003
  • We consider an efficient parametric estimation method of spatial dependence in weak stationary processes. Spatial dependence is modeled through variogram and correlogram. Most of parametric estimation methods of correlogram use two step method; nonparametric estimation and parametric integration. We bind these two steps into one step by using GEE method instead of least squares type optimization. Our one step method is more efficient statistically and gives a clear interpretation of related concepts used in traditional two step methods.

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On a Modified k-spatial Medians Clustering

  • Jhun, Myoungshic;Jin, Seohoon
    • Journal of the Korean Statistical Society
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    • v.29 no.2
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    • pp.247-260
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    • 2000
  • This paper is concerned with a modification of the k-spatial medians clustering. To find a suitable number of clusters, the number k of clusters is incorporated into the k-spatial medians clustering criterion through a weight function. Proposed method for the choice of the weight function offers a reasonable number of clusters. Some theoretical properties of the method are investigated along with some examples.

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Geovisualization of Migration Statistics Using Flow Mapping Based on Web GIS (Web GIS 기반 유선도 작성을 통한 인구이동통계의 지리적 시각화)

  • Kim, Kam-Young;Lee, Sang-Il
    • Journal of the Korean Geographical Society
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    • v.47 no.2
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    • pp.268-281
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    • 2012
  • In spite of the usefulness of migration statistics in spatially understanding social processes and identifying social effects of spatial processes, services and analyses of the statistics have been restricted due to the complexity of their data structure. In addition, flow mapping functionality which is a useful method to explore and visualize the migration statistics has yet to be fully represented in modern GIS applications. Given this, the purpose of this research is to demonstrate the possibility of flow mapping and the exploratory spatial analysis of the migration statistics in a Web GIS environment. For this, the characteristics of the statistics were examined from database, GIS, and cartographic perspectives. Then, O-D structure of the migration statistics was converted to spatial data appropriate to f low mapping based on the characteristics. The interface of Web GIS is specialized the migration statistics and provides exploratory visualization by allowing dynamic interactions such as spatial focusing and attribute filtering.

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Comparison between Kriging and GWR for the Spatial Data (공간자료에 대한 지리적 가중회귀 모형과 크리깅의 비교)

  • Kim Sun-Woo;Jeong Ae-Ran;Lee Sung-Duck
    • The Korean Journal of Applied Statistics
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    • v.18 no.2
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    • pp.271-280
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    • 2005
  • Kriging methods as traditional spatial data analysis methods and geographical weighted regression models as statistical analysis methods are compared. In this paper, we apply data from the Ministry of Environment to spatial analysis for practical study. We compare these methods to performance with monthly carbon monoxide observations taken at 116 measuring area of air pollution in 1999.

Comparison of Neighborhood Information Systems for Lattice Data Analysis (격자자료분석을 위한 이웃정보시스템의 비교)

  • Lee, Kang-Seok;Shin, Key-Il
    • The Korean Journal of Applied Statistics
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    • v.21 no.3
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    • pp.387-397
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    • 2008
  • Recently many researches on data analysis using spatial statistics have been studied in various field and the studies on small area estimations using spatial statistics are in actively progress. In analysis of lattice data, defining the neighborhood information system is the most crucial procedure because it also determines the result of the analysis. However the used neighborhood informal ion system is generally defined by sharing the common border lines of small areas. In this paper the other neighborhood information systems are introduced and those systems are compared with Moran's I statistic and for the comparisons, Economic Active Population Survey (2001) is used.

Spatial Clustering Method Via Generalized Lasso (Generalized Lasso를 이용한 공간 군집 기법)

  • Song, Eunjung;Choi, Hosik;Hwang, Seungsik;Lee, Woojoo
    • The Korean Journal of Applied Statistics
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    • v.27 no.4
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    • pp.561-575
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    • 2014
  • In this paper, we propose a penalized likelihood method to detect local spatial clusters associated with disease. The key computational algorithm is based on genlasso by Tibshirani and Taylor (2011). The proposed method has two main advantages over Kulldorff's method which is popoular to detect local spatial clusters. First, it is not needed to specify a proper cluster size a priori. Second, any type of covariate can be incorporated and, it is possible to find local spatial clusters adjusted for some demographic variables. We illustrate our proposed method using tuberculosis data from Seoul.