A call to `rw`

can be used in the 'formula' argument of `epim`

, allowing
random walks for the reproduction number. Does not evaluate arguments. Simply creates a
list with the information needed for the stan data to be parsed correctly.

rw(time, gr, prior_scale = 0.2)

## Arguments

time |
An optional name defining the random walk time periods for each
date and group. This must be a column name found in the `data` argument to `epim` .
If not specified, determined by the dates column implied by the `formula` argument to `epim`
is used. |

gr |
Same as for `time` , except this defines the grouping to use for the random walks. A separate walk is defined
for each group. If not specified a common random walk is used for all groups. |

prior_scale |
The steps of the walks are independent zero mean normal with an unknown scale hyperparameter. This scale is given
a half-normal prior. `prior_scale` sets the scale parameter of this hyperprior. |

## Value

A list to be parsed internally.

## Examples