Page 388 - Special Topic Session (STS) - Volume 3
P. 388

STS551 Zamira Hasanah Zamzuri et al.









                  Then,  the  log  of  the  above  function  is  maximized.  The  expansion  of  the
                  function is given as












                      3)  Sampling 
                                    
                         We    want    to   sample    from    a   density   proportional   to

                      {∏    ( | ,  −1 )} ∏   ( | ,  , π) .  Since  this  is  also  not  a
                        =1      0  0   =1      
                      recognized distribution, the Metropolis-Hastings algorithm is needed. The
                      same technique as (1) is used for this stage. Then, we sample from the
                      proposal density, multivariate-t.
                      Let







                  Then, the log of the above function is maximized. The expansion of the
                  function is given as












                      4)  Sampling  −1
                         We  want  to  sample  from  from  a  density  proportional  to
                       ( −1 | ,  ) ∏    ( |). We can see that this function is distributed
                                          
                                             
                              0
                      
                                      =1
                                  0
                      as Wishart, hence we can sample directly from the Wishart distribution
                      using the Gibbs sampling.
                      The derivation of the function is given as
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