meters to probability densities that are
not themselves modeled probabilistically. In Stan, unmodeled
parameters that appear in the <code>data</code> block may be specified on a
per-model execution basis as part of the data read. In the above
model, <code>mu_mu</code> and <code>sigma_mu</code> are configurable unmodeled
parameters.</p>
<p>Unmodeled parameters that are hard coded in the model must be declared
in the <code>transformed data</code> block. For example, the unmodeled
parameters <code>alpha</code>