Defines a list specifying the structure of the observation model. Custom settings can be supplied which override the defaults.

## Arguments

- family
Character string defining the observation model. Options are Negative binomial ("negbin"), the default, and Poisson.

- phi
A numeric vector of length 2, defaults to 0, 1. Indicates the mean and standard deviation of the normal prior used for the observation process.

- weight
Numeric, defaults to 1. Weight to give the observed data in the log density.

- week_effect
Logical defaulting to

`TRUE`

. Should a day of the week effect be used in the observation model.- week_length
Numeric assumed length of the week in days, defaulting to 7 days. This can be modified if data aggregated over a period other than a week or if data has a non-weekly periodicity.

- scale
List, defaulting to an empty list. Should an scaling factor be applied to map latent infections (convolved to date of report). If none empty a mean (

`mean`

) and standard deviation (`sd`

) needs to be supplied defining the normally distributed scaling factor.- likelihood
Logical, defaults to

`TRUE`

. Should the likelihood be included in the model.- return_likelihood
Logical, defaults to

`FALSE`

. Should the likelihood be returned by the model.

## Examples

```
# default settings
obs_opts()
#> $family
#> [1] "negbin"
#>
#> $phi
#> [1] 0 1
#>
#> $weight
#> [1] 1
#>
#> $week_effect
#> [1] TRUE
#>
#> $week_length
#> [1] 7
#>
#> $scale
#> list()
#>
#> $likelihood
#> [1] TRUE
#>
#> $return_likelihood
#> [1] FALSE
#>
# Turn off day of the week effect
obs_opts(week_effect = TRUE)
#> $family
#> [1] "negbin"
#>
#> $phi
#> [1] 0 1
#>
#> $weight
#> [1] 1
#>
#> $week_effect
#> [1] TRUE
#>
#> $week_length
#> [1] 7
#>
#> $scale
#> list()
#>
#> $likelihood
#> [1] TRUE
#>
#> $return_likelihood
#> [1] FALSE
#>
# Scale reported data
obs_opts(scale = list(mean = 0.2, sd = 0.02))
#> $family
#> [1] "negbin"
#>
#> $phi
#> [1] 0 1
#>
#> $weight
#> [1] 1
#>
#> $week_effect
#> [1] TRUE
#>
#> $week_length
#> [1] 7
#>
#> $scale
#> $scale$mean
#> [1] 0.2
#>
#> $scale$sd
#> [1] 0.02
#>
#>
#> $likelihood
#> [1] TRUE
#>
#> $return_likelihood
#> [1] FALSE
#>
```