spatial analysis
DESCRIPTION
Spatial Analysis. Chapter One. Spatial Analysis. Patterns of spatially distributed points. Correlation with environmental variables. Interpolations and predictive models. - PowerPoint PPT PresentationTRANSCRIPT
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Spatial Analysis
Chapter One
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Spatial Analysis
• Patterns of spatially distributed points.
• Correlation with environmental variables.
• Interpolations and predictive models.
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• Spatial autocorrelation -> spatial patterns, aggregation. Based on distance to neighbors. Kaplan-Meier estimator, Moran’s I.
• Spatial Interpolation -> estimate variables in unknown locations based on known locations. Krigging.
• Spatial Regression -> regression analysis considering spatial relationships.
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• Spatial Interaction -> Gravity models. Spatially explicit interactions. Movement patterns, people movement, vehicle traffic. Fish schools and bird flocks. Game theory.
• Simulations.
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Why do we care about this???
• Analyzing distributions and factors shaping them.
• Predicting locations.• Relative influence of factors in distributions.• Variation in pressure to understand selection
and evolution.
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Today…
• Generate random points in a plot, using Poisson Distribution.
• Analyze the aggregation pattern of points using the Kaplan-Meier Estimator.
• Use a Chagas’ Disease data set.
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Poisson Distribution
• Discrete probability distribution.• Rare events.
• Use in spatial analysis is a generalization, based on λ -> “intensity” of event occurrence.
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Kaplan-Meier Estimator
• Estimation of distance distribution.
• Calculation of G(r) random distribution of nearest neighbor distance in a given space.
• Compare the observed distribution with the random G(r)
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The Data Set
• Chagas Disease vectors Spatial Distribution -> Maria Victoria Suarez (PUCE).
• Look for the relationship between human settlements and spatial distribution of Chagas disease vectors in the surrounding natural areas.
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Chagas Disease
• Tropical Disease caused by Trypanosoma cruzi
• Vector -> Triatomine hemipterans.
• Chronic disease. Lethal causing liver and/or heart failure
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Methodology
• Random sampling of nests and palm trees in a 600x600m plot, adjacent to a human settlement in natural or semi-natural habitat.
• Compare the distribution of positive points, with the random expected distribution using G(r)