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Spatial Analysis. Chapter One. Spatial Analysis. Patterns of spatially distributed points. Correlation with environmental variables. Interpolations and predictive models.
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Spatial Analysis Chapter One
Spatial Analysis • Patterns of spatially distributed points. • Correlation with environmental variables. • Interpolations and predictive models.
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.
Spatial Interaction -> Gravity models. Spatially explicit interactions. Movement patterns, people movement, vehicle traffic. Fish schools and bird flocks. Game theory. • Simulations.
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.
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.
Poisson Distribution • Discrete probability distribution. • Rare events. • Use in spatial analysis is a generalization, based on λ -> “intensity” of event occurrence.
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)
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.
Chagas Disease • Tropical Disease caused by Trypanosomacruzi • Vector -> Triatominehemipterans. • Chronic disease. Lethal causing liver and/or heart failure
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)