f="#ref-LewandowskiKurowickaJoe:2009" role="doc-biblioref">2009</a>)</span>. In particular, the Lewandowski et al.&nbsp;prior allows the correlation matrix to be shrunk toward the unit matrix while the scales are given independent priors.</p>
<p>In BUGS you need to define all variables. In Stan, if you declare but don’t define a parameter it implicitly has a flat prior (on the scale in which the parameter is defined). For example, if you have a parameter <code>p</code> declared as</p>
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