Bio::Tree::Statistics(3)

NAME
Bio::Tree::Statistics - Calculate certain statistics for a Tree

SYNOPSIS
  use Bio::Tree::Statistics;

DESCRIPTION
This should be where Tree statistics are calculated. It was previously where statistics from a Coalescent simulation. Currently it is empty because we have not added any Tree specific statistic calculations to this module yet. We welcome any contributions.

FEEDBACK

  Mailing Lists
User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to the Bioperl mailing list. Your participation is much appreciated.

  bioperl-l@bioperl.org                  - General discussion
  http://bioperl.org/wiki/Mailing_lists  - About the mailing lists

  Reporting Bugs
Report bugs to the Bioperl bug tracking system to help us keep track of the bugs and their resolution. Bug reports can be submitted via the web:

  http://bugzilla.open-bio.org/

AUTHOR - Jason Stajich
Email jason AT bioperl.org

CONTRIBUTORS
Heikki Lehvaslaiho, heikki at bioperl dot org

APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _

  new
 Title   : new
 Usage   : my $obj = Bio::Tree::Statistics->new();
 Function: Builds a new Bio::Tree::Statistics object
 Returns : Bio::Tree::Statistics
 Args    :

  assess_bootstrap
 Title   : assess_bootstrap
 Usage   : my $tree_with_bs = $stats->assess_bootstrap(\@bs_trees);
 Function: Calculates the bootstrap for internal nodes based on
 Returns : L<Bio::Tree::TreeI>
 Args    : Arrayref of L<Bio::Tree::TreeI>s

  cherries
  Example    : cherries($tree, $node);
  Description: Count number of paired leaf nodes
               in a binary tree
  Returns    : integer
  Exceptions :
  Args       : Bio::Tree::TreeI object
               Bio::Tree::NodeI object within the tree, optional

Commonly used statistics assume a binary tree, but this methods returns a value even for trees with polytomies.

  Tree-Trait statistics
The following methods produce desciptors of trait distribution among leaf nodes within the trees. They require that a trait has to be set for each leaf node. The tag methods of Bio::Tree::Node are used to store them as key/value pairs. In this way, one tree can store more than on trait.

Trees have method add_traits() to set trait values from a file.

  ps
  Example    : ps($tree, $key, $node);
  Description: Calculates Parsimony Score (PS) from Fitch 1971
               parsimony algorithm for the subtree a defined
               by the (internal) node.
               Node defaults to the root.
  Returns    : integer, 1< PS < n, where n is number of branches
  Exceptions : leaf nodes have to have the trait defined
  Args       : Bio::Tree::TreeI object
               trait name string
               Bio::Tree::NodeI object within the tree, optional

Fitch, W.M., 1971. Toward deﬁning the course of evolution: minimal change for a speciﬁc tree topology. Syst. Zool. 20, 406–416.

  ai
  Example    : ai($tree, $key, $node);
  Description: Calculates the Association Index (AI) of Whang et
               al. 2001 for the subtree defined by the (internal)
               node.  Node defaults to the root.
  Returns    : real
  Exceptions : leaf nodes have to have the trait defined
  Args       : Bio::Tree::TreeI object
               trait name string
               Bio::Tree::NodeI object within the tree, optional

Association index (AI) gives a more fine grained results than PS since the result is a real number. ~0 <= AI.

Wang, T.H., Donaldson, Y.K., Brettle, R.P., Bell, J.E., Simmonds, P.,
  2001. Identiﬁcation of shared populations of human immunodeﬁciency
  Virus Type 1 infecting microglia and tissue macrophages outside the
  central nervous system. J. Virol. 75 (23), 11686–11699.

  mc
  Example    : mc($tree, $key, $node);
  Description: Calculates the Monophyletic Clade (MC) size statistics
               for the subtree a defined by the (internal) node.
               Node defaults to the root;
  Returns    : hashref with trait values as keys
  Exceptions : leaf nodes have to have the trait defined
  Args       : Bio::Tree::TreeI object
               trait name string
               Bio::Tree::NodeI object within the tree, optional

* Monophyletic Clade (MC) size statistics by Salemi at al 2005. It is calculated for each trait value. 1<= MC <= nx, where nx is the number of tips with value x:

   pick the internal node with maximim value for
      number of of tips with only trait x

MC was defined by Parker et al 2008.

Salemi, M., Lamers, S.L., Yu, S., de Oliveira, T., Fitch, W.M., McGrath, M.S.,
   2005. Phylodynamic analysis of Human Immunodeﬁciency Virus Type 1 in
   distinct brain compartments provides a model for the neuropathogenesis of
   AIDS. J. Virol. 79 (17), 11343–11352.

Parker, J., Rambaut A., Pybus O., 2008. Correlating viral phenotypes
   with phylogeny: Accounting for phylogenetic uncertainty Infection,
   Genetics and Evolution 8 (2008), 239–246.