Proc Variogram on OLS residual

[Moshood]

Hi everyone,

A spatial analysis is to be carried out on yield attribute with geoferenced information in easting and northing UTM coordinates system. I intend to carried out variogram model on the OLS residual with the intention of having the idea of what my initial starting values of geostatistical parameters (range, sill) will be by the time Spatial covariance model was done in PROC MIXED. I proceed as follows

proc mixed data=spatial method=reml;

          model yield=/outp=residat;

run;

proc variogram data-residat outv=variodat;

          compute lagdistance= maxlag=

          coordinates xc=easting yc=northing;

           var resid;

run;

I am having difficulty in knowing what to choose as lagdistance and maxlag. Could anyone help me out? Having got those values, what would be the next thing to be done to get initial values for the range and sills.

Thanks while looking forward to reading from you.