computeELBO computes the variational lower bound on the log-likelihood, also called the ELBO, for a mixed membership model.
computeELBO(model)a mixedMemModel object created by the mixedMemModel constructor.
computeELBO returns the lower bound on the log-likelihood, a real number.
The lower bound (ELBO) is the objective function in the variational EM algorithim. It is a function of the latent variables (\(\phi\) and \(\delta\)) and the parameters (\(\alpha\) and \(\theta\)) that be derived from Jensen's inequality:
\(E_Q{\log[p(X,Z, \Lambda)]} - E_Q{\log[Q(Z, \Lambda|\phi, \delta)]} \le\log P(obs |\alpha, \theta) \)