scedast {nnDiag}R Documentation

Test of Scedasticity

Description

Assesses the relationship between standard deviations of residuals with respect to response variable predictions for a test of scedasticity.

Usage

scedast(object)

Arguments

object object of class "nnDgrps"

Value

An object of class "nnDsced", which is a list containing the following components:

mean.prediction a vector of means of the groups of predictions
stdev.residuals a vector of the standard deviations of the residual groups

Author(s)

Brian Walters walte137@msu.edu

References

McRoberts, R.E. (2009) Diagnostic tools for nearest neighbors techniques when used with satellite imagery, Remote Sensing of Environment. 113, 489–499.

Examples

data(LuceVolume)
data(LuceVolume_indx)

##First use grouper to make the "nnDgrps" object
grps <- grouper(LuceVolume$ref.volume, LuceVolume$pred.vol_k18, LuceVolume_indx)

x <- scedast(object = grps)
## Not run: 
plot(x)
plot(x, ylab = "Standard Deviation of Volume Residuals (ft^3/acre)",
xlab = "Mean Volume Predictions(ft^3/acre)", ylim = c(500,2500), xlim =
c(500,2500), pch = 20)
## End(Not run)

[Package nnDiag version 0.0-5 Index]