• Title/Summary/Keyword: spatial statistic

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Optimizing the maximum reported cluster size for normal-based spatial scan statistics

  • Yoo, Haerin;Jung, Inkyung
    • Communications for Statistical Applications and Methods
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    • v.25 no.4
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    • pp.373-383
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    • 2018
  • The spatial scan statistic is a widely used method to detect spatial clusters. The method imposes a large number of scanning windows with pre-defined shapes and varying sizes on the entire study region. The likelihood ratio test statistic comparing inside versus outside each window is then calculated and the window with the maximum value of test statistic becomes the most likely cluster. The results of cluster detection respond sensitively to the shape and the maximum size of scanning windows. The shape of scanning window has been extensively studied; however, there has been relatively little attention on the maximum scanning window size (MSWS) or maximum reported cluster size (MRCS). The Gini coefficient has recently been proposed by Han et al. (International Journal of Health Geographics, 15, 27, 2016) as a powerful tool to determine the optimal value of MRCS for the Poisson-based spatial scan statistic. In this paper, we apply the Gini coefficient to normal-based spatial scan statistics. Through a simulation study, we evaluate the performance of the proposed method. We illustrate the method using a real data example of female colorectal cancer incidence rates in South Korea for the year 2009.

Research on Application of Spatial Statistics for Exploring Spatio-Temporal Changes in Patterns of Commercial Landuse (상업적 토지이용 패턴의 시공간 변화 탐색을 위한 공간통계 기법 적용 연구)

  • Shin, Jung-Yeop;Lee, Gyoung-Ju
    • Journal of the Korean Geographical Society
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    • v.42 no.4
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    • pp.632-647
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    • 2007
  • Lots of geographic phenomena have dynamic spatial patterns with time changes, and there have been lots of researches on exploring these dynamic spatial patterns. However, most of these researches focused on the static pattern analysis in a given period, rather than dealing with dynamic changes in the spatial pattern over time with the continual or cumulative perspective. For this reason, investigation of the inertia of spatial process in terms of temporal changes is needed. From this background, the purpose of this paper is to propose the methodology to explore the changes in spatial pattern cumulatively by considering the inertia of the spatial statistics over time, and to apply it to the case study That is, we introduce the new spatial statistic, and produce the z-values of the statistic using Monte Carlo Simulation, and then to explore the changes in spatial patterns over time cumulatively. To do this, the method to combine the J statistic with CUSUM statistic for exploring spatial patterns, and to apply it to the changes in the commercial landuse in Erie County, New York State. Through the proposed method for spatio-temporal Patterns, we could explore continual changes effectively in the spatial patterns reflecting the statistics by temporal spot cumulatively.

A Study on Spatial Statistical Perspective for Analyzing Spatial Phenomena in the Framework of GIS: an Empirical Example using Spatial Scan Statistic for Detecting Spatial Clusters of Breast Cancer Incidents (공간현상 분석을 위한 GIS 기반의 공간통계적 접근방법에 관한 고찰: 공간 군집지역 탐색을 위한 공간검색통계량의 실증적 사례분석)

  • Lee, Gyoung-Ju;Kweon, Ihl
    • Spatial Information Research
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    • v.20 no.1
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    • pp.81-90
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    • 2012
  • When analyzing geographical phenomena, two properties need to be considered. One is the spatial dependence structure and the other is a variation or an uncertainty inhibited in a geographic space. Two problems are encountered due to the properties. Firstly, spatial dependence structure, which is conceptualized as spatial autocorrelation, generates heterogeneous geographic landscape in a spatial process. Secondly, generic statistics, although suitable for dealing with stochastic uncertainty, tacitly ignores location information im plicit in spatial data. GIS is a versatile tool for manipulating locational information, while spatial statistics are suitable for investigating spatial uncertainty. Therefore, integrating spatial statistics to GIS is considered as a plausible strategy for appropriately understanding geographic phenomena of interest. Geographic hot-spot analysis is a key tool for identifying abnormal locations in many domains (e.g., criminology, epidemiology, etc.) and is one of the most prominent applications by utilizing the integration strategy. The article aims at reviewing spatial statistical perspective for analyzing spatial processes in the framework of GIS by carrying out empirical analysis. Illustrated is the analysis procedure of using spatial scan statistic for detecting clusters in the framework of GIS. The empirical analysis targets for identifying spatial clusters of breast cancer incidents in Erie and Niagara counties, New York.

A STUDY ON THE EFFECT OF POWER TRANSFORMATION IN SPATIAL STATISTIC ANALYSIS

  • LEE JIN-HEE;SHIN KEY-IL
    • Journal of the Korean Statistical Society
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    • v.34 no.3
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    • pp.173-183
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    • 2005
  • The Box-Cox power transformation is generally used for variance stabilization. Recently, Shin and Kang (2001) showed, under the Box-Cox transformation, invariant properties to the original model under the large mean and relatively small variance assumptions in time series analysis. In this paper we obtain some invariant properties in spatial statistics. Spatial statistics, Invariant Property, Variogram, Box-Cox power Transformation.

A Study on Estimates to Longevity Population of Small Area and Distribution Patterns using Vector based Dasymetric Mapping Method (벡터기반 대시매트릭 기법을 이용한 소지역 장수인구 추정 및 분포패턴에 관한 연구)

  • Choi, Don-Jeong;Kim, Young-Seup;Suh, Yong-Cheol
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.29 no.5
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    • pp.479-485
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    • 2011
  • A number of case studies that find distribution of longevity population and influencing factors through the spatial data fusion using GIS techniques are growing. The majority cases of these studies are adopt census administrative boundary data for the spatial analysis. However, these methods cannot fully explain the phenomenon of longevity because there are a variety of spatial characteristics within the census administrative boundaries. Therefore, studies of spatial unit are required that realistically reflect the phenomenon of human longevity. The dasymetric mapping method enables to product of spatial unit more realistic than census administrative boundary map and statistic estimates of small area utilizing diversity spatial information. In this study, elderly population of small area has been estimated within statistically significant level that applied the vector based dasymetric mapping method. Also, the cluster analysis confirmed that the variation of local spatial relationship within census administrative boundary. The result of this study implied that the need for local-level studies of the human longevity and the validity of the dashmetric mapping techniques.

Face Region Detection and Verification using both WPA and Spatially Restricted Statistic (공간 제약 특성과 WPA를 이용한 얼굴 영역 검출 및 검증 방법)

  • Song, Ho-Keun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.3
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    • pp.542-548
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    • 2006
  • In this paper, we propose a face region detection/verification method using wavelet packet analysis and structural statistic for frontal human color image. The method extracts skin color lesions from input images, first. and then applies spatial restrictive conditions to the region, and determines whether the region is face candidate region or not. In second step, we find eye region in the face candidate region using structural statistic for standard korean faces. And in last step, the face region is verified via wavelet packet analysis if the face torture were satisfied to normal texture conditions.

Evaluation of White Matter Abnormality in Mild Alzheimer Disease and Mild Cognitive Impairment Using Diffusion Tensor Imaging: A Comparison of Tract-Based Spatial Statistics with Voxel-Based Morphometry (확산텐서영상을 이용한 경도의 알츠하이머병 환자와 경도인지장애 환자의 뇌 백질의 이상평가: Tract-Based Spatial Statistics와 화소기반 형태분석 방법의 비교)

  • Lim, Hyun-Kyung;Kim, Sang-Joon;Choi, Choong-Gon;Lee, Jae-Hong;Kim, Seong-Yoon;Kim, Heng-Jun J.;Kim, Nam-Kug;Jahng, Geon-Ho
    • Investigative Magnetic Resonance Imaging
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    • v.16 no.2
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    • pp.115-123
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    • 2012
  • Purpose : To evaluate white matter abnormalities on diffusion tensor imaging (DTI) in patients with mild Alzheimer disease (AD) and mild cognitive impairment (MCI), using tract-based spatial statistics (TBSS) and voxel-based morphometry (VBM). Materials and Methods: DTI was performed in 21 patients with mild AD, in 13 with MCI and in 16 old healthy subjects. A fractional anisotropy (FA) map was generated for each participant and processed for voxel-based comparisons among the three groups using TBSS. For comparison, DTI data was processed using the VBM method, also. Results: TBSS showed that FA was significantly lower in the AD than in the old healthy group in the bilateral anterior and right posterior corona radiata, the posterior thalamic radiation, the right superior longitudinal fasciculus, the body of the corpus callosum, and the right precuneus gyrus. VBM identified additional areas of reduced FA, including both uncinates, the left parahippocampal white matter, and the right cingulum. There were no significant differences in FA between the AD and MCI groups, or between the MCI and old healthy groups. Conclusion: TBSS showed multifocal abnormalities in white matter integrity in patients with AD compared with old healthy group. VBM could detect more white matter lesions than TBSS, but with increased artifacts.

Spatial Cluster Analysis for Earthquake on the Korean Peninsula

  • Kang, Chang-Wan;Moon, Sung-Ho;Cho, Jang-Sik;Lee, Jeong-Hyeong;Choi, Seung-Bae;Beum, Soo-Gyun
    • Journal of the Korean Data and Information Science Society
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    • v.17 no.4
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    • pp.1141-1150
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    • 2006
  • In this study, we performed spatial cluster analysis which considered spatial information using earthquake data for Korean peninsula occurred on 1978 year to 2005 year. Also, we look into how to be clustered for regions using earthquake magnitude and frequency based on spatial scan statistic. And, on the basis of the results, we constructed earthquake map by earthquake outbreak risk and gave a possible explanation for the results of spatial cluster analysis.

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Anomaly Detection from Hyperspectral Imagery using Transform-based Feature Selection and Local Spatial Auto-correlation Index (자료 변환 기반 특징 선택과 국소적 자기상관 지수를 이용한 초분광 영상의 이상값 탐지)

  • Park, No-Wook;Yoo, Hee-Young;Shin, Jung-Il;Lee, Kyu-Sung
    • Korean Journal of Remote Sensing
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    • v.28 no.4
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    • pp.357-367
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    • 2012
  • This paper presents a two-stage methodology for anomaly detection from hyperspectral imagery that consists of transform-based feature extraction and selection, and computation of a local spatial auto-correlation statistic. First, principal component transform and 3D wavelet transform are applied to reduce redundant spectral information from hyperspectral imagery. Then feature selection based on global skewness and the portion of highly skewed sub-areas is followed to find optimal features for anomaly detection. Finally, a local indicator of spatial association (LISA) statistic is computed to account for both spectral and spatial information unlike traditional anomaly detection methodology based only on spectral information. An experiment using airborne CASI imagery is carried out to illustrate the applicability of the proposed anomaly detection methodology. From the experiments, anomaly detection based on the LISA statistic linked with the selection of optimal features outperformed both the traditional RX detector which uses only spectral information, and the case using major principal components with large eigen-values. The combination of low- and high-frequency components by 3D wavelet transform showed the best detection capability, compared with the case using optimal features selected from principal components.