[R-sig-Geo] problems with universal kriging

[Matevž Pavlič]

Hi all, 

 

i have some problems with universal kriging predictions. 

I would like to create a map using the X and Y as co-predictors. 

Attached is a sample data set  (temp.csv) and code (UK.txt) which is used in the predictions. 

 

The problem is, when i use universal kriging  i get really strange results. 

When I use this line for predicting :

 

z.uk<-krige(Globina~I(Y^2)+I(X^2)+I(X)+I(Y), DF, grd, vrmf.u)

 

the results are really strange: as you can see the Globina variable is reanging from 1.2 to 40 but predictions are from 457.6 to 2594.0.

 

> summary(DF$Globina)

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 

   1.20   10.00   12.00   12.96   15.00   40.00 

 

> summary(z.uk$var1.pred)

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 

  457.6  1206.0  1524.0  1525.0  1843.0  2594.0 

 

 

When i use thisl line for prediction :

z.uk<-krige(Globina~I(Y^2)+I(X^2)+I(X)+I(Y), DF, grd, vrmf.u)

 

the results are still strange, but different. Again Globina is ranging from 1.2 to 40 and the predicted values are ranging from -230.6 to  -207.6 !

 

> summary(DF$Globina)

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 

   1.20   10.00   12.00   12.96   15.00   40.00 

 

> summary(z.uk$var1.pred)

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 

 -230.6  -223.0  -221.6  -221.4  -220.0  -207.2 

 

What am I doing wrong?

 

thanks for the help, m

 

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