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nugget in variogram

5 messages · piero campa, Piero Campalani, kapo coulibaly +1 more

#
Hi,
I am trying to fit my first variograms.
I'm however noticing some weird behaviour I cannot explain.
I'm a 100% newbie.

- without setting a nugget element (so that it should be implicitly 0, isn't
it? In fact the resulting variogram has 0 nugget), the psill and range of
the fitted variogram don't change on different psill inputs.
- If I explicitly set a nugget to 0, then actually the nugget is no more 0,
but higher.
- I tried also setting the fit.sills booleans to TRUE or FALSE to see what
would change, but the output does not really care about it.

Does someone have any hint about this?

Thank you.
Regards,
Piero
#
model psill range
1   Exp     1   300

and
model psill range
1   Nug     0     0
2   Exp     1   300

are definitions of exactly the same variogram, with zero nugget --
passing either to krige() will yield identical results. If they are
passed to fit.variogram, in the first case no nugget will be fitted, but
in the second case a (zero or positive) nugget will be fitted.

Hth,
On 12/14/2010 06:09 PM, Piero Campalani wrote: