Generally the experimental variogram is most accurate for small
values of , with uncertainties growing rapidly when
is large.
The influence of this problem may be decreased by using
moving neighborhoods. With this variant, only the points that lie
within a prefixed radios
from point
are considered,
provided that we are left with an adequate number of
data (Fig. 2.4).
The redius
is selected so that the lag
will remain
with the range of maximum certainty for
.
This approach leads also to high saving in the
computational cost of the procedure because each linear system is now much
smaller (Gaussian elimination has a computational cost proportional to ,
where
is the number of equations).