DEFINITION
Space-Time Clustering is a method of data analysis whereby the data objects are grouped with reference to a specific place and time. Space time clustering is therefore involve finding clusters that emerge during a particular time interval at particular places. Spatial cluster detection allows the identification of locations, shapes and sizes of potential anomalous spatial regions. The analysis of these clusters aid in the understanding of current patterns and prediction of future ones using a data-driven approach or a model-based approach.
SYNONYMS: Spatial surveillance, Space-Time Scan Statistic, Analysis Tab, Spatial Window Tab, Temporal Window Tab
BACKGROUND
The goal of space-time cluster detection is to identify the location, shapes and sizes of potentially anomalous spatial regions and analyze these clusters to determine if they are contingent clusters or legit cluster portraying some unforeseen information. Space-time cluster analysis therefore leads to the establishment of the characteristics, scale, scope and detection of various phenomena.
METHODOLOGY
Statistical local measures space-time clustering can be achieved using space-time scan statistic; while global space-time clustering is possible using algorithms like the Knox index, mantel test and space-time K-function.
Space-time clustering involves a spatio-temporal scan of a space with a 3 dimensional search window that independently, but simultaneously captures the space and time. The procedure involved in spatial scan can be summarized as follows:
Generate a model under the null hypothesis (no clusters) and under an alternative hypothesis.
Derive a score function using the null hypothesis and the alternative hypothesis (hypothesis gotten using the...
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...ed areas. When we want to study a change in pattern or frequency, Cluster and Outlier Analysis could prove effective. Grouping Analysis could be valuable in studying characteristics of individual patterns, e.g. disease outbreaks.
REFERENCES
Assuncao, Renato, et al. "Space-time cluster identification in point processes." The Canadian Journal of Statistics. 2007. 9-25.
Cromley, Ellen k. and Sara McLafferty. GIS and Public Health. Guilford Press, 2011.
Gould, MS, S Wallenstein and M Kleinman. "Time-space clustering of teenage suicide." PubMed. 1990.
Kulldorff , Martin , et al. "A space-time permutation scan statistic for disease outbreak detection." PLOS Medicine. 2005.
Wilson , Margo and Martin Daly. "Spatial-Temporal Clustering of Chicago Homicides." Proceedings of the 4th Annual Symposium of the Homicide Research Working Group. Washington, DC, 1997. 160-163.
Geographic segmentation is when the market is divided into locations, regions, countries, cities, states and so forth. In the advertisement, geographical segmentation is identifiable when the guy, Ian Rappaport is taken from the bar into the city, where they make a stop in actress; Minka Kelly’s dressing room and they move on further to another location where he meets actor; Don Chead...
The Centroid is then computed again by taking mean of all points coming in the same cluster.
Why are some neighborhoods more prone to experience violent episodes than others? What is the extent and in what sociologically measurable ways do communities contribute to the causation and prevention of crime in their neighborhoods? Are neighborhood-level predictors adequate to explain differences in violent crime rates in the respective communities? These are some of the questions addressed by this statistically intense paper published in Science 1997, by Sampson, Raudenbush and Earls.
4-Spatial Differentiation:The spread of the organization within its jurisdiction. Police agencies with a single headquarters facility are less spatially differentiated than those with precinct houses, substations, and other offices located within neighborhoods.
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http://www.ojip.usdoj.gov/nij. [Internet Website]. "Crime and Place: Plenary Papers of the 1997 Conference on Criminal Justice Research and Evaluation."
G. (2016, September 4). Serial killer statistics. Retrieved November 11, 2017, from http://maamodt.asp.radford.edu/serial killer information center/project
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It is also convenient to write the spacetime interval in a more compact form. We therefore introduce the 4x4 matrix, the metric. The metric gives us a way of taking the norm of a vector, or the dot product of two vectors.