Evaluating data stability in aggregation structures across spatial scales: revisiting the modifiable areal unit problem     

Jonathan K. Nelson  Cynthia A. Brewer 《制图学和地理信息科学》2013,40(1):35-50

ABSTRACT

Socioeconomic and health analysts commonly rely on areally aggregated data, in part because government regulations on confidentiality prohibit data release at the individual level. Analytical results from areally aggregated data, however, are sensitive to the modifiable areal unit problem (MAUP). Levels of aggregation as well as the arbitrary and modifiable sizes, shapes, and arrangements of zones affect the validity and reliability of findings from analyses of areally aggregated data. MAUP, long acknowledged, remains unresolved. We present an exploratory spatial data analytical approach (ESDA) to understand the scalar effects of MAUP. To characterize relationships between data aggregation structures and spatial scales, we develop a method for statistically and visually exploring the local indicators of spatial association (LISA) exhibited between a variable and itself across varying levels of aggregation. We demonstrate our approach by analyzing the across-scale relationships of aggregated 2010 median income for the State of Pennsylvania and 2005–2009 cancer diagnosis rates for the State of New York between county–tract, tract–block group, and county–block group level US census designated enumeration units. This method for understanding the relationship between MAUP and spatial scale provides guidance to researchers in selecting the most appropriate scales to aggregate, analyze, and represent data for problem-specific analyses.  相似文献   

‘Here,we don't just trade goods,we also “sell” people's lives’: Sari‐sari stores as nodes of partial surveillance in a Philippine fishing community     

Nelson Turgo 《Singapore journal of tropical geography》2013,34(3):373-389

Home‐based neighbourhood stores (locally known in the Philippines as sari‐sari stores) are a ubiquitous feature of most Philippine communities. They are small to medium‐size trade stores not unlike convenience stores in the West where people buy goods in small quantities. In the Philippines, these stores play a vital role in providing everyday economic sustenance to low‐income communities. But more than an economic hub, sari‐sari stores also function as a social hub that connects people and acts as eyes and ears of the community through the people who make use of their services. In a sense, sari‐sari stores are the community's ‘myopticon’ where people's day‐to‐day dealings with everyone in the community and its environs are reported and discursively brought under the gaze of the ‘entire community’. Being myopticon as opposed to Foucault's panopticon, surveillance in sari‐sari stores is partial, non‐hierarchicalized and could be resisted by people in the community. Nonetheless, regardless of the ‘myoptic’ features of sari‐sari stores, their presence in the community ‘interpellates’ everyone's daily existence and instantiates a discursive space from which a structure of informal social control is enacted among community members. Sari‐sari stores then are an important reminder of how our built environment is also about contestation and negotiation of everyday life as we make use of space and as the architectonics of space both constrain and empower our manoeuvring in places.  相似文献   

METHODOLOGY: A DEVICE FOR MONITORING SOIL MOVEMENT IN PEATLANDS     

Frederick E. Nelson 《自然地理学》2013,34(3):275-281

Traditional methods of tracking soil movements may be unreliable in soils containing a large proportion of organic matter owing to the composition and mechanical properties of peat. A simple, inexpensive, and reusable “anchored” target can be used to monitor both vertical and horizontal components of soil movement in fibrous peat. The target is unlikely to be affected adversely by flooding, frost heave, or animal disturbance, and is applicable to a wide range of geomorphic problems in peatlands. [Key words: frost heave, peat, peat landforms, soil movement, survey targets.]  相似文献   

Multi‐scale correlations between topography and vegetation in a hillside catchment of Honduras     

A. Nelson  T. Oberthür  S. Cook 《International journal of geographical information science》2013,27(2):145-174

All systems have causes and effects that can be appreciated at different spatial scales. Understanding and representing the complexity of multi‐scale patterns in maps and spatial models are key research objectives. We describe the use of three types of correlation analyses: (1) a standard Pearson correlation coefficient, (2) a ‘global’ multi‐scale correlation, and (3) local geographically weighted correlation. These methods were applied to topographic and vegetation indices in a small catchment in Honduras that is representative of the country's hillsides agro‐ecosystem which suffers from severe environmental degradation due to land‐use decisions that lead to deforestation, overgrazing, and unsustainable agricultural. If the geographical scale at which topography matters for land‐use allocation can be determined, then integration of knowledge systems can be focused. Our preliminary results show that: (1) single‐scale correlations do not adequately represent the relationship between NDVI and topographic indices; (2) peaks in the global multi‐scale correlations in agricultural areas coincided with the median farm size, but there was no evidence of any community or larger‐scale land‐use planning or optimization; and (3) local multi‐scale correlations varied considerably from the global results at all scales, and these variations have a strong spatial structure which may indicate local optimization of land use.  相似文献   

Statistical analysis of spatial and spatio-temporal point patterns,Third Edition,by Peter J. Diggle,Boca Raton,FL, CRC Press, 2013, 263 pp., $49.99, $79.95 EUR 62, 38 (hardback), ISBN 13:978-1-4665-6023-9     

Trisalyn Nelson 《International journal of geographical information science》2013,27(4):690-691

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An Object Extraction Approach for Impervious Surface Classification with Very-High-Resolution Imagery     

Jennifer Elizabeth Miller  Stacy A. C. Nelson  George R. Hess 《The Professional geographer》2013,65(2):250-264

Detailed land cover maps provide important information for research and decision-making but are often expensive to develop and can become outdated quickly. Widespread availability of aerial photography provides increased accessibility of high-resolution imagery and the potential to produce high-accuracy land cover classifications. However, these classifications often require expert knowledge and are time consuming. Our goal was to develop an efficient, accurate technique for classifying impervious surface in urbanizing Wake County, North Carolina. Using an iterative training technique, we classified 111 nonmosaicked, very-high-resolution images using the Feature Analyst software developed by Visual Learning Systems. Feature Analyst provides object extraction classifications by analyzing spatial context in relation to spectral data to classify high-resolution imagery. Our image classification results were 95 percent accurate in impervious surface extraction, with an overall total accuracy of 92 percent. Using this method, users with relatively limited geographic information system (GIS) training and modest budgets can produce highly accurate object-extracted classifications of impervious and pervious surface that are easily manipulated in a GIS.  相似文献   

A Data Based Model to Predict Landslide Induced by Rainfall in Rio de Janeiro City     

Fábio T. de Souza  Nelson. F. F. Ebecken 《Geotechnical and Geological Engineering》2012,30(1):85-94

Landslide prediction is complex and involves many factors, such as geotechnical, geological, topographical, and even meteorological. This work presents a methodology by using a Data Mining approach in order to predict landslide occurrences induced by rainfall in Rio de Janeiro city. Landslide and rain data records from 1998 to 2001 were obtained from field technical reports and 30 automatic rain gauges, respectively. It was also collected data regarding soil parameters, including urban areas, forest, vulnerability, among others, and totalizing 46 soil variables. All the information was inserted into a Geographic Information Systems. Clustering (Dendrogram and k-means) and Statistical (Principal Component Analysis and Correlation) techniques were used to regionalize the rain data and select the rain gauges to be input on Artificial Neural Networks , which were used to replace the missing rain values. The landslide volume variable also presented missing values and it was completed by the k-Nearest Neighbor method. After data preparation, some models were built to predict landslide and rainfall using Data Mining techniques. The obtained model’s performance is also analyzed.  相似文献   

The construction of Slovenia as a European tourism destination in guidebooks     

Velvet Nelson 《Geoforum》2012,43(6):1099-1107

Geographic research in tourism recognizes destinations to be socio-spatial constructions shaped by historic, cultural, and political discourses. These discourses are reflected in and reproduced by tourism literature such as guidebooks. Guidebooks are a key resource for potential tourists to learn about a destination. These texts produced by international publishing companies draw upon existing discourses for a place that will allow external audiences to make sense of the contextual information provided for the destination. At the same time, they reify these discourses by presenting them to readers as objective facts. This paper uses discourse analysis to examine tourism guidebooks for the European destination region, the Eastern and/or Central European sub-region, and Slovenia. In particular, it examines the competing and conflicting discourses of Eastern and Central Europe in these externally authored and oriented texts to understand the socio-spatial construction of Slovenia as a European tourism destination.  相似文献   

4350–3130 Ma detrital zircons in the Southern Cross Granite‐Greenstone Terrane,Western Australia: Implications for the early evolution of the Yilgarn Craton     

S. Wyche  D. R. Nelson  A. Riganti 《Australian Journal of Earth Sciences》2013,60(1):31-45

SHRIMP U–Pb zircon analysis indicates that detrital zircons from extensive quartzite units in the Southern Cross Granite‐Greenstone Terrane of the central Yilgarn Craton have ages ranging from ca 4350 Ma to ca 3130 Ma. Regional mapping studies indicate that the quartzites lie at the stratigraphic base of the exposed succession. The detrital zircon age profiles of the Southern Cross Granite‐Greenstone Terrane quartzites are remarkably similar to those of quartzites in the Narryer and South West Terranes, in the northwest and southwest of the Yilgarn Craton respectively, and are significantly older than any igneous rocks that have been dated anywhere in the Yilgarn Craton other than the Narryer Terrane. Similar detrital‐zircon‐bearing quartzites have not been identified in the Murchison Granite‐Greenstone Terrane. These age profiles suggest that the quartzites have a common depositional history. Granites in the central Yilgarn Craton are mainly younger than ca 2750 Ma and contain rare xenocrystic zircons older than 3100 Ma. If the central and western Yilgarn quartzites were all deposited at approximately the same time, the lack of preserved continental crust in the Southern Cross and Murchison Granite‐Greenstone Terranes, and the South West Terrane, that is older than 3100 Ma, suggests that pre‐3100 Ma Narryer‐like continental crust may have been rifted or extensively reworked during deposition of greenstone successions between ca 3000 and ca 2700 Ma. If not, then a ca 4350 Ma detrital zircon in the Southern Cross Granite‐Greenstone Terrane indicates more widespread, very old, continental crust than has previously been identified.  相似文献   

Replication of a terrain stability mapping using an Artificial Neural Network   总被引：1，自引：0，他引：1  

Mihai Pavel  R. Jonathan Fannin  John D. Nelson 《Geomorphology》2008,97(3-4):356-373

Subjective geomorphic mapping is a method commonly used for landslide hazard zonation. This method relies heavily on the skills and experience of the mapper, and therefore, its major drawbacks are the high costs and lack of consistency between products generated by different terrain mappers. In this study a method for cost-effective and consistent replication of subjective geomorphic mappings is demonstrated, by using a type of Artificial Neural Network named Learning Vector Quantization. This paper presents a study conducted in the Canadian province of British Columbia employing a high-quality data set. By utilizing Learning Vector Quantization, stable and unstable terrains were delineated with a similarity of approximately 91%, compared to the mapping produced by terrain specialists. Also, in this process, slope, elevation, aspect, and existing geomorphic processes were identified as the terrain attributes that contributed most to the quality of the mapping.  相似文献