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.

	[[alternative HTML version deleted]]

