unstr {brms} | R Documentation |

## Set up UNSTR correlation structures

### Description

Set up an unstructured (UNSTR) correlation term in brms. The function does not evaluate its arguments – it exists purely to help set up a model with UNSTR terms.

### Usage

```
unstr(time, gr)
```

### Arguments

`time` |
An optional time variable specifying the time ordering of the observations. By default, the existing order of the observations in the data is used. |

`gr` |
An optional grouping variable. If specified, the correlation structure is assumed to apply only to observations within the same grouping level. |

### Value

An object of class `'unstr_term'`

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

### See Also

### Examples

```
## Not run:
# add an unstructured correlation matrix for visits within the same patient
fit <- brm(count ~ Trt + unstr(visit, patient), data = epilepsy)
summary(fit)
## End(Not run)
```

[Package

*brms*version 2.21.0 Index]