tmackey-esriaustralia-com-au-esridist

How to show clusters of events of the same category occuring within spacetime window?

Discussion created by tmackey-esriaustralia-com-au-esridist on Nov 8, 2012
Latest reply on Nov 9, 2012 by bharold-esristaff
Hi,

I have a set of points representing crimes, and want to show all clusters of specific crime categories which fall within a space/time window. For example, "show me where there are clusters of vehicle thefts which occurred within the same 1km area in 24 hours". From a crime analysis point of view, the question that I'm hoping to answer is "where have bursts of activity occurred, and which incidents were involved in them, so I can go back to my database and investigate those incidents". I've played around a lot, and looked into the help for Space-Time Cluster Analysis and associated pages, but it's not quite answering my question.

I've used the generate spatial weights matrix tool to specify a 1 km, 1 day neighbour matrix. I've then converted that to a table, which gives me a list of which features are adjacent (in space & time) to which other features. If I run that process once per category, that's my "clustering analysis" complete, really - I don't want to do any statistical stuff from here. Will I have to write my own tool from here to show these clusters on the map (e.g. as MBRs around the points in question)? I guess it's a relatively small step from the neighbour table to such a tool, but I don't want to write something if I don't have to.

I feel like this is either a lot easier than I'm making it out to be, or a lot harder. I have a niggling feeling I should be able to do the same thing with just SQL. If ArcGIS had multidimensional indexing then it could be a 4D buffer/union. Is this a 'hidden feature' that I don't know about? I guess I could hack time into the Z coordinate but that's a bit... well, hacky.

Thanks for your help.

(Cross-posted from the spatial statistics subforum)

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