essie: Essie

Description Usage Arguments Details Value

Description

Fit an Essie model

Usage

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essie(model, grid, epsilon1 = 0.001, epsilon2 = 1e-16,
  verbose = interactive())

Arguments

model

a model structure generated by essieThresholdModel.

grid

a raster object defining the grid

epsilon1

likelihood tolerance

epsilon2

transition probability tolerance.

verbose

report progress at prompt?

Details

Essie is a discrete analog of Stella that only considers locations on a lattice of grid points.

The posterior probability that the tag is at a particular location is determined by a two pass recursive algorithm. The forward sweep propogates location information forward in time, the backward sweep propogates location information backward in time, and the full posterior is a compromise of these two.

The method is only approximate and is controlled by the two tolerances epsilon1 and epsilon2. The first limits the precision of the likelihood - locations for which the likelihood fall below epsilon1 of its maximum are ignored. The second limits the precision of the transition probabilities - locations for which the probability below epsilon2 of the maximum are ignored in the movement calculation. The smaller these parameters are set, the slower but more accurate the fit.

Value

a list with elements

grid

a raster object that defines the grid.

times

the times corresponding to the location estimates.

lattice

a sparse grid representation of the posterior location probabilities.


KateGoodenough/RoL-SGAT documentation built on June 11, 2019, 1:29 p.m.