Lecture 2

# Lecture 2 - 1 Lab#1 Point Pattern Analysis using Quadrat...

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Unformatted text preview: 1 Lab #1. Point Pattern Analysis using Quadrat counts Carry out a point pattern analysis using quadrat counts based on grid cells superimposed on a given study (a two dimensional surface) containing a spatial distribution of points that represent the locations of an occurrence of some phenomenon or an event of interest. The point pattern can be a real, hypothetical, or generated, and should contain a fairly large number of points. The statistical analysis should assume a Poisson process (i.e., a random distribution of points) in the assessment of the null hypothesis, and should test at α=.05 and .01 significance or 95% and 99% confidence levels using a variance-mean ratio approach, chi-square, and/or the K-S test (D statistic). Spatial Analysis of Subterranean Termite Data: A Point Pattern Analysis Dennis Zielstra GEOMATICS University of Florida Fort Lauderdale Research and Education Center with modifications/edits by Timothy Fik Objective • Apply different spatial analysis methods on a point dataset: point pattern of cases where subterranean termites are known to have affected individual housing units within the South Florida market. • Goal is to test the null hypothesis of complete spatial randomness . • Research Questions : Is the point pattern random or systematic? Do we see a tendency for the clustering or dispersion of points within the study area? Background • Subterranean termites are one of the most destructive insects/pests in the United States. • Economic costs due to termite damage of wood and wooden structures run into the tens of billions of dollars each year in the U.S. housing market. • In nature, subterranean termites are beneficial because they break down cellulose into usable nutrients (humus)… but they can be very destructive to wood-framed properties. Reticulitermes (Queen and Soldier) Reticulitermes (Queen and Worker) • Empirical evidence suggests that some markets and geographic areas are more affected than others… and that the destruction is non-random . • Older housing and wood-framed structures tend to be affected with greater regularity than newer housing or those constructed of cement blocks. Hence, urban morphology and its geo-history tend to imply that the spatial distribution of affected housing units would tend to produce a point pattern that is highly clustered over space. • The presence of termites is often not readily noticed because their activity is hidden behind wallboards, siding or wood trim. • Native subterranean termite species (Reticulitermes) are widely spread throughout the U.S. Damage caused by Reticulitermes (house basement) Termite damage… telltale signs of an infestation. Severe termite damage … in its advanced stages. Facts on Subterranean and other termites: Subterranean termites are similar to drywood termites, and primarily nest in the soil to obtain moisture (though aerial nests are not uncommon as long as all castes of the colony are present and moisture is available). and moisture is available)....
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Lecture 2 - 1 Lab#1 Point Pattern Analysis using Quadrat...

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