e algorithm.
An adaptation phase finds a good value for the step size scaling
parameter <code>eta</code>. The evidence lower bound (ELBO) is the variational
objective function and is evaluated based on a Monte Carlo estimate.
The variational inference algorithm in Stan is stochastic, which makes
it challenging to assess convergence. That is, while the algorithm
appears to have converged in <span class="math inline">\(\sim\)</span> 250 iterations, the algorithm runs
for another few thousand iterations until 