Creates a Dirichlet prior distribution for the four joint response probabilities of two binary endpoints in one group.
Value
An object of class c("qdm_prior_dirichlet", "qdm_prior")
with element alpha, a named numeric vector of length 4.
Details
The four cells are ordered as "00", "01", "10" and
"11", where the first digit is the response on endpoint 1 and the
second digit is the response on endpoint 2 (1 = response, 0 = no
response). The marginal response rates are therefore
\(\pi_1 = p_{10} + p_{11}\) and \(\pi_2 = p_{01} + p_{11}\).
With alpha = rep(0.25, 4), each marginal response rate has a
Beta(0.5, 0.5) prior distribution.
See also
Other priors:
prior_beta(),
prior_gamma(),
prior_niw(),
prior_nix(),
prior_vague()
Examples
prior_dirichlet(rep(0.25, 4))
#> Prior: Dirichlet(alpha = (0.25, 0.25, 0.25, 0.25))