Likelihood for the Bayesian Nowcast

Count observation model for the (truncation-corrected) case counts.

Usage

poisson_likelihood(mu = numeric(0))

nb_likelihood(mu = numeric(0), phi = lognormal_prior(log(20), 0.5))

Arguments

mu

Log-scale mean intercept prior (or fixed numeric).

phi

Negative-binomial overdispersion prior (or fixed numeric); NB only. Defaults to lognormal_prior(log(20), 0.5). This is the only place to set the overdispersion prior — nowcast() reads it from the model and does not accept its own phi argument.

Value

A likelihood_class object.

Examples

poisson_likelihood()
#> Poisson(mu)
nb_likelihood()
#> NegBin(mu, phi ~ LogNormal(2.996, 0.500))
# Wider overdispersion (heavier-tailed counts) -- set via the likelihood:
nb_likelihood(phi = lognormal_prior(log(5), 0.5))
#> NegBin(mu, phi ~ LogNormal(1.609, 0.500))