Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2008

[Date Index] [Thread Index] [Author Index]

Search the Archive

Fisher scoring algorithm

  • To: mathgroup at smc.vnet.net
  • Subject: [mg90962] Fisher scoring algorithm
  • From: Francogrex <franco at grex.org>
  • Date: Fri, 1 Aug 2008 02:58:26 -0400 (EDT)

Hello, this is very probably a mathematical question not really
technical but a technical advice might help. I am trying to find the
expectation by solving the following below:

FullSimplify[
 Sum[(1/(n! Gamma[\[Alpha]]) z^
     n \[Beta]^\[Alpha] (z + \[Beta])^(-n - \[Alpha])
      Gamma[n + \[Alpha]])*(PolyGamma[1, a] -
     PolyGamma[1, a + n]), {n, 0, Infinity}]]

It's the product of the log of the 2nd derivative of alpha (from the
likelihood) by the likelihood: negative binomial distribution (n is
integer z is real, and likelihood and 2nd deriv should be products and
sums respectively of many n(s) and z(s) but taken here as only one
point for simplicity). This has come from a poisson-gamma marginal
distribution, for which I am trying to find the (parameters) alpha and
the beta by using the fisher scoring algorithm. But mathematica does
not find a solution to the above. Any hints or help appreciated.
thanks.


  • Prev by Date: Re: Performance of Array Addition
  • Next by Date: Re: Constructing vector using table
  • Previous by thread: Re: Performance of Array Addition
  • Next by thread: Re: Constructing vector using table