Dear spatial statisticians and R users, I am trying to model a temporal marked point process with time-varying covariates and I am looking for the most appropriate function among several ones. (The events are violent events, such as fightings, in African countries). I want to model both the time/location of the events and at least one of the mark (the intensity of the event, measured for example by the number of persons killed).
Events are collected over a few years. The time-resolution of the events is the day, while the covariates vary more slowly. The events have latitude and longitude, while the covariates are raster data (1km x 1km grid). I had a look at the following packages but I'm not sure I found the right solution yet: spatstat splancs PtProcess spatstat seems to have the correct object to handle my dependant variables (the ppx class: 2D space + time) but if I'm correct the ppm() model fitting function cannot handle this (it only works with ppp). Am I missing something? I saw at http://www.spatstat.org/ that this branch is in development. Any news / schedule on that? PtProcess does allow to estimate a time dependent marked point process (using etas_spatial() ). However, apparently, only the history of the point process itself can be taken into account (there are marks but they are no covariates: there is no data for locations without events). One workaround might be to include in the point process dummy events with (near-)zero intensity for all (or sampled) time-space cells and to attach the covariates as marks. What do you think? splancs does not seem to support this but has a nice space-time kernel smoothing function (kernel3d) and ability to display the result (kerview). I could transform the point process into a time-varying surface, but do not know how to model it either. The main aim is to measure the impact of the covariates on the point process. Ideally, the model should allow for time and space autocorelation among events (clustering is likely), similar to what the etas_spatial() function permits. Thanks for any comment! Regards, Mayeul KAUFFMANN PS: for reference, some messages I found close to my problem: https://stat.ethz.ch/pipermail/r-sig-geo/2010-March/007909.html https://stat.ethz.ch/pipermail/r-sig-geo/2009-September/006438.html https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20091023/b33321bb/attachmen t.pl _____________________________________________________ Dr. Mayeul KAUFFMANN, Conflict Specialist European Commission, Joint Research Centre (JRC) Institute for the Protection and Security of the Citizen (IPSC) Global Security and Crisis Management - ISFEREA Via E. Fermi 2749 - I-21027 Ispra (VA), ITALY Phone: (+39) 033278 5071 http://isferea.jrc.ec.europa.eu/Staff/Pages/Kauffmann-Mayeul.aspx (Office: building 48c, 1st floor, room 123. TP: 483) _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
