sar {brms} | R Documentation |

## Spatial simultaneous autoregressive (SAR) structures

### Description

Set up an spatial simultaneous autoregressive (SAR) term in brms. The function does not evaluate its arguments – it exists purely to help set up a model with SAR terms.

### Usage

```
sar(M, type = "lag")
```

### Arguments

`M` |
An object specifying the spatial weighting matrix.
Can be either the spatial weight matrix itself or an
object of class |

`type` |
Type of the SAR structure. Either |

### Details

The `lagsar`

structure implements SAR of the response values:

`y = \rho W y + \eta + e`

The `errorsar`

structure implements SAR of the residuals:

`y = \eta + u, u = \rho W u + e`

In the above equations, `\eta`

is the predictor term and `e`

are
independent normally or t-distributed residuals. Currently, only families
`gaussian`

and `student`

support SAR structures.

### Value

An object of class `'sar_term'`

, which is a list
of arguments to be interpreted by the formula
parsing functions of brms.

### See Also

### Examples

```
## Not run:
data(oldcol, package = "spdep")
fit1 <- brm(CRIME ~ INC + HOVAL + sar(COL.nb, type = "lag"),
data = COL.OLD, data2 = list(COL.nb = COL.nb),
chains = 2, cores = 2)
summary(fit1)
plot(fit1)
fit2 <- brm(CRIME ~ INC + HOVAL + sar(COL.nb, type = "error"),
data = COL.OLD, data2 = list(COL.nb = COL.nb),
chains = 2, cores = 2)
summary(fit2)
plot(fit2)
## End(Not run)
```

*brms*version 2.21.0 Index]