[R-sig-Geo] Variance unchanging with krige in gstat with iterations

[Edzer Pebesma]

This is a property of (linear) kriging -- if the observation locations
and variogram model do not change, kriging variances will not change
either. They're independent of observed values. To understand why, try
to understand the equations used to compute them.
--
Edzer

Tobin Cara wrote:
> Hello,
>
> I am performing kriging with an external drift and ordinary kriging in a loop to have predicted values at each time step.
>
> The predicted values are changing reasonably, however, the variance is not changing after the first time step.
>
> Here is my simple for loop:
>
> # KED
> list_ked <- vector("list",72)
>
> for(i in 1:72){
>  list_ked[[i]] <- krige(Prec00[,i]~Z, locations=DataCoord, newdata=elev, model = fitted_vario)
> }
>
> # OK
> list_ok <- vector("list",72)
>
> for(i in 1:72){
>      list_ok[[i]] <- krige(Prec00[,i]~1, DataCoord, newdata=coord_points, model = fitted_vario)
> }
>
> Would anyone know the solution?
>
> Thank you very much,
>
> Cara
>
> 	[[alternative HTML version deleted]]
>
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de/
http://www.springer.com/978-0-387-78170-9 e.pebesma at wwu.de