downdate_scaled_gamma_poisson

function downdate_scaled_gamma_poisson(x:Integer, a:Real, k':Real, θ':Real) -> (Real, Real)

Downdate the parameters of a scaled Gamma distribution with a Poisson likelihood.

  • x: The variate.
  • a: Scale.
  • k': Posterior shape.
  • θ': Posterior scale.

Returns: the prior hyperparameters k and θ.