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geoR (version 1.5-6)

output.control: Defines output options for prediction functions

Description

Auxiliary function defining output options for krige.bayes and krige.conv.

Usage

output.control(n.posterior, n.predictive, moments, n.back.moments,
               simulations.predictive, mean.var, quantile,
               threshold, sim.means, sim.vars, signal, messages)

Arguments

n.posterior
number of samples to be taken from the posterior distribution. Defaults to 1000.
n.predictive
number of samples to be taken from the predictive distribution. Default equals to n.posterior.
moments
logical. Indicates whether the moments of the predictive distribution are returned. If lambda = 1 there is no transformation/back-transformation. If lambda = 0 or lambda = 0.5 the moments are back-tra
n.back.moments
number of sample to back-transform moments by simulation. Defaults to 1000.
simulations.predictive
logical. Defines whether to draw simulations from the predictive distribution. Only considered if prediction locations are provided in the argument locations of the main functions. Defaults to FALSE but changed to
mean.var
logical (optional). Indicates whether mean and variances of the simulations of the predictive distributions are computed and returned.
quantile
a (optional) numeric vector. If provided indicates whether quantiles of the simulations from the predictive distribution are computed and returned. If a vector with numbers in the interval $[0,1]$ is provided, the output includes the o
threshold
a (optional) numerical vector. If one or more values are provided, object named probabilities is included in the output. This object contains, for each prediction location, the probability that the variable is less than or
sim.means
logical (optional). Indicates whether mean of each of the conditional simulations of the predictive distribution should be computed and returned. Defaults to TRUE if simulations from the predictive are required.
sim.vars
logical (optional). Indicates whether variance of each of the conditional simulations of the predictive distribution should be computed and returned. Defaults to FALSE.
signal
logical indicating whether the signal or the variable is to be predicted. Defaults to NULL and changed internally in the functions which call output.control. See DETAILS below.
messages
logical. Indicates whether or not status messages are printed on the output device while the function is running. Defaults to TRUE.

Value

  • A list with processed arguments to be passed to the main function.

Details

SIGNAL

This function is typically called by the geoR's prediction functions krige.bayes and krige.conv defining the output to be returned by these functions.

The underlying model $$Y(x) = \mu + S(x) + \epsilon$$ assumes that observations $Y(x)$ are noisy versions of a signal $S(x)$ and $Var(\epsilon)=\tau^2$ is the nugget variance.

If $\tau^2 = 0$ the $Y$ and $S$ are indistiguishable. If $\tau^2 > 0$ and regarded as measurement error the option signal defines whether the $S$ (signal = TRUE) or the variable $Y$ (signal = FALSE) is to be predicted. For the latter the predictions will "honor" the data, i.e. at data locations predictions will coincide with the data. For unsampled locations, when there is no transformation of the data, the predicted values will be the same regardless whether signal = TRUE or FALSE but the predictions variances will differ.

By default krige.bayes sets signal = TRUE and krige.conv sets signal = FALSE.

The function krige.conv has an argument micro.scale. If $micro.scale > 0$ the error term is divided as $\epsilon = \epsilon_{ms} + \epsilon_{me}$ and the nugget variance is divided into two terms: micro-scale variance and measurement error. If signal = TRUE the term $\epsilon_{ms}$ is regarded as part of the signal and consequently the micro-scale variance is added to the prediction variance. If signal = FALSE the total error variance $\tau^2$ is added to the prediction variance.

See Also

The prediction functions krige.bayes and krige.conv.