{fields}R Documentation

Standard errors of predictions


Evaluates the standard error of predictions on a surface.

Usage, grid.list=NA, extrap=FALSE, chull.mask,...)


object A fitted model object of a certain class
grid.list A list with as many components as variables describing the surface. All components should have a single value except the two that give the grid points for evaluation. If the matrix or data frame has column names, these must appear in the grid list. See the grid.list help file for more details. If this is omitted and the fit just depends on two variables the grid will be made from the ranges of the observed variables.
chull.mask Whether to restrict the fitted surface to be on a convex hull, NA's are assigned to values outside the convex hull. chull.mask should be a sequence of points defining a convex hull. Default is to form the convex hull from the observations if this argument is missing (and extrap is false).
extrap Extrapolation beyond the range of the data. If false function will be restricted to the convex hull of the observed data or the convex hull defined from the points from the argument chull.mask.
... Any additional arguments that will passed to the function specific to the fit object.


This function is generic and will call the appropriate function to calculate the standard errors for the object class. It operation is simple a grid is created based on the grid list or from the fit object. The prediction standard error are evaluated on the grid using Finally the standard errors are reformed into a surface object suitable for plotting.


A surface object with components A vector of standard errors for the predicted values.

See Also

predict, predict.surface,, plot.surface, as.surface


fit<-Tps(ozone$x,ozone$y)                # tps fit 
out<- fit)

surface( out)

# or ... 

image.plot( out)

[Package fields version 2.0 Index]