Auxiliary function required in the calculation of the
Fisher information matrix. It represents the conditional expected value E(W_i^s|Z_i), with s = -2; i.e.,
latent W_i^(-2) given the observed Z_i.
Usage
Ew2z(z, mu, phi)
Arguments
z
response vector with 0 < z_i < 1.
mu
mean parameter (vector having the same size of z).
phi
precision parameter (vector having the same size of z).