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)
} # }
```