Dear All, In my yield data, I have longitude and latitude as spherical coordinates which are converted into projected coordinates - easting and northing for variogram modelling, yield as attribute variable, and elevation. I fitted my empirical variogram as empvar<-variogram(yield~1,canmod.sp,cutoff=600,width=3, cressie=TRUE). In some documents I come across, some fitted the model using easting and northing as covariate to yield as yield ~easting+northing rather than yield ~1. which one do you advise me to use yield ~easting+northing or yield ~1. Thank you for your usual response and understanding.
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