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Measuring Aggregation of Events about a Mass Using Spatial Point Pattern Methods.

ABSTRACT: We present a methodology that detects event aggregation about a mass surface using 3-dimensional study regions with a point pattern and a mass present. The Aggregation about a Mass function determines aggregation, randomness, or repulsion of events with respect to the mass surface. Our method closely resembles Ripley's K function but is modified to discern the pattern about the mass surface. We briefly state the definition and derivation of Ripley's K function and explain how the Aggregation about a Mass function is different. We develop the novel function according to the definition: the Aggregation about a Mass function times the intensity is the expected number of events within a distance h of a mass. Special consideration of edge effects is taken in order to make the function invariant to the location of the mass within the study region. Significance of aggregation or repulsion is determined using simulation envelopes. A simulation study is performed to inform researchers how the Aggregation about a Mass function performs under different types of aggregation. Finally, we apply the Aggregation about a Mass function to neuroscience as a novel analysis tool by examining the spatial pattern of neurotransmitter release sites as events about a neuron.

SUBMITTER: Smith MO

PROVIDER: S-EPMC5642986 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Measuring Aggregation of Events about a Mass Using Spatial Point Pattern Methods.

Smith Michael O MO Ball Jackson J Holloway Benjamin B BB Erdelyi Ferenc F Szabo Gabor G Stone Emily E Graham Jonathan J Lawrence J Josh JJ

Spatial statistics 20150528

We present a methodology that detects event aggregation about a mass surface using 3-dimensional study regions with a point pattern and a mass present. The Aggregation about a Mass function determines aggregation, randomness, or repulsion of events with respect to the mass surface. Our method closely resembles Ripley's K function but is modified to discern the pattern about the mass surface. We briefly state the definition and derivation of Ripley's K function and explain how the Aggregation abo ...[more]

PMID: 29046865

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Project description:ObjectiveTo compare measures of spatial access to care commonly used by policy makers and researchers with the more comprehensive enhanced two-step floating catchment area (E2SFCA) method.Study settingFourteen southwestern Pennsylvania counties.Study designWe estimated spatial access to buprenorphine-waivered prescribers using three commonly used measures-Euclidean travel distance to the closest prescriber, travel time to the closest provider, and provider-to-population ratios-and the E2SFCA. Unlike other measures, the E2SFCA captures provider capacity, potential patient volume, and travel time to prescribers.Data collection/extraction methodsWe measured provider capacity as the number of buprenorphine prescribers listed at a given address in the Drug Enforcement Agency's 2020 Controlled Substances Act Registrants Database, and we measured potential patient volume as the number of nonelderly adults in a given census tract as reported by the 2018 American Community Survey. We estimated travel times between potential patients and prescribers with Bing Maps and Mapbox application programming interfaces. We then calculated each spatial access measure using the R programming language. We used each measure of spatial access to identify census tracts in the lowest quintile of spatial access to prescribers.Principal findingsThe Euclidean distance, travel time, and provider-to-population ratio measures identified 48.3%, 47.2%, and 69.9% of the census tracts that the E2SFCA measure identified as being in the lowest quintile of spatial access to care, meaning that these measures misclassify 30%-52% of study area census tracts as having sufficient spatial access to buprenorphine prescribers.ConclusionsMeasures of spatial access commonly used by policy makers do not sufficiently accurately identify geographic areas with relatively low access to prescribers of buprenorphine. Using the E2SFCA in addition to the commonly used measures would allow policy makers to precisely target interventions to increase spatial access to opioid use disorder treatment and other types of health care services.

Dataset Information

Measuring Aggregation of Events about a Mass Using Spatial Point Pattern Methods.

Publications

Measuring Aggregation of Events about a Mass Using Spatial Point Pattern Methods.

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