) for all covariates in <code>fixed</code>, one parameter is required if the
covariate is not in <code>mixture</code>, ng paramaters are required if the
covariate is also in <code>mixture</code>;</p>
<p>(3) the variance of each random-effect specified in <code>random</code> (including
the intercept) when <code>idiag=TRUE</code>, or the inferior triangular
variance-covariance matrix of all the random-effects when
<code>idiag=FALSE</code>;</p>
<p>(4) only when <code>nwg=TRUE</code>, ng-1 parameters are requir