Great! Thanks. I am looking more to the "complicated" measure of bivariate point processes which are linked. I have some better direction now and will take a close look at spatstat.
On Thu, Oct 13, 2011 at 10:13 AM, Barry Rowlingson < [email protected]> wrote: > > > On Thu, Oct 13, 2011 at 1:40 PM, <[email protected]> wrote: > >> Im still not entirely sure what youre getting at: spatial correlation >> of origin/destination locations to each other? Or some characteristic of >> the origin/destination pairs? It sounds like the latter, but then the >> question is correlated with what?**** >> >> >> > > It sounds like you've got a bivariate point pattern - a set of origin > points and a set of destination points - and you want to ask questions about > the relationship of the underlying processes... > > Read: > > > http://www.amazon.co.uk/Statistical-Analysis-Spatial-Point-Patterns/dp/0340740701 > > which should give you an outline. > > You probably want to use some kind of bivariate K-function. This estimates > the number of events that occur within a distance of an event, based on the > type. If type 2 and type 1 events are being generated by the same process, > then the number of type 1's and type 2's within a distance from a type 1 or > a type 2 event should be the same (within estimation errors, in practice). > For example, if thefts mostly happen in the east side of town, and > recoveries on the other side of the tracks, then you'll see more thefts near > thefts than recoveries near to thefts. If the number of recoveries near > thefts is the same as the number of other thefts, then you can possibly > conclude the reverse, that its all happening everywhere. An interesting > complication could be that you can link each theft event with its recovery > event, so maybe what you really have is a spatial line process. Possibly you > might want to look at the length, direction, orientation, and > endpoint-locations of the lines... > > The spatstat package can do all the point-pattern stuff, and splancs has > some K-function code too... > > Barry > > [[alternative HTML version deleted]]
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