  We know that the marginals in a Dirichlet distribution are beta variates
exhibiting a negative correlation. But we can construct two linear combinations
of such marginals in such a way to obtain a positive correlation. We discuss
the restrictions that are to be imposed on the parameters to accomplish such a
result. In the case the sampling from the Dirichlet distribution is performed
through a generalization of Johnk's method we discuss the efficiency of the
algorithm implementing the method.
