lass='kw'>NULL</span>,
  <span class='kw'>alpha_mean</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>alpha_sd</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>beta_mean</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>beta_sd</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>gamma_mean</span> <span class='kw'>=</span> <span class='kw'>NULL</span>,
  <span class='kw'>gamma_sd</s