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Specify a spatial explicit offset as bias

Source: R/add_offset.R
add_offset_bias.Rd

Including offsets is another option to integrate spatial prior information in linear and additive regression models. Offsets shift the intercept of the regression fit by a certain amount. Although only one offset can be added to a regression model, it is possible to combine several spatial-explicit estimates into one offset by calculating the sum of all spatial-explicit layers.

Usage

add_offset_bias(x, layer, add = TRUE, points = NULL)

# S4 method for class 'BiodiversityDistribution,SpatRaster'
add_offset_bias(x, layer, add = TRUE, points = NULL)

Arguments

x

distribution() (i.e. BiodiversityDistribution) object.

layer

A sf or SpatRaster object with the range for the target feature.

add

logical specifying whether new offset is to be added. Setting this parameter to FALSE replaces the current offsets with the new one (Default: TRUE).

points

An optional sf object with key points. The location of the points are then used to calculate the probability that a cell has been sampled while accounting for area differences. (Default: NULL).

Value

Adds a bias offset to a distribution object.

Details

This functions emulates the use of the add_offset() function, however applies an inverse transformation to remove the provided layer from the overall offset. So if for instance a offset is already specified (such as area), this function removes the provided bias.layer from it via "offset(log(off.area)-log(bias.layer))"

Note that any transformation of the offset (such as log) has do be done externally!

If a generic offset is added, consider using the add_offset() function. If the layer is a expert-based range and requires additional parametrization, consider using the function add_offset_range() or the bossMaps R-package.

References

  • Merow, C., Allen, J.M., Aiello-Lammens, M., Silander, J.A., 2016. Improving niche and range estimates with Maxent and point process models by integrating spatially explicit information. Glob. Ecol. Biogeogr. 25, 1022–1036. https://doi.org/10.1111/geb.12453

See also

Other offset: add_offset(), add_offset_elevation(), add_offset_range(), rm_offset()

Examples

if (FALSE) { # \dontrun{
 x <- distribution(background) |>
   add_predictors(covariates) |>
   add_offset_bias(samplingBias)
} # }