Hello R list, I need to compute empirical variograms using data from a large geographic area (~10^6 km2). Although I could not find a specific reference, I assume that both geoR and gstat calculate distances among data points assuming points are on a flat surface (using the Pythagorean Theorem). Because the location of my data is large and located near the pole, assuming that latitude and longitude are coordinates on a flat surface would introduce a -possibly large- bias in the empirical variogram estimate. My questions are the following:
a) Does geoR and gstat assume that points are on a flat surface? b) If I first calculate the distances among points using the Haversine formula, it is possible to calculate the variogram with a matrix of distances among points (where n is the number of observations) and a vector of observation values? Any help would be appreciated. Julian Julian M. Burgos Fisheries Acoustics Research Lab School of Aquatic and Fishery Science University of Washington 1122 NE Boat Street Seattle, WA 98105 Phone: 206-221-6864 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
