NAME
    Statistics::EfficiencyCI - Robust confidence intervals on efficiencies

SYNOPSIS
      use Statistics::EfficiencyCI qw(efficiency_ci);
      my $confidence_level = 0.683;
      my ($mode, $lower_cl, $upper_cl) = efficiency_ci($k, $N, $confidence_level);
  
      # With default confidence level of "1sigma" == 0.683
      my ($mode, $lower_cl, $upper_cl) = efficiency_ci($k, $N);

DESCRIPTION
    This module implements robust confidence interval calculations on
    efficiency-like quantities. The algorithm is explained in the note by
    Marc Paterno linked in the references below.

    The employed method does not suffer from the usual boundary issue of the
    uncertainty calculation based on the Binomial model: At an efficiency "e
    = k/N" with small "k", the confidence interval will be asymmetric and
    will not go below 0, which the simple calculation based on the Binomial
    PDF will for confidence levels above the equivalent of one sigma. It
    also does not suffer from the problem that the uncertainty vanishes at
    "k=0" and "k=N".

  EXPORTS
    This module will optionally export the "efficiency_ci" function.

SEE ALSO
    Marc Paterno's note on calculating the uncertainty on an efficiency:
    :<http://home.fnal.gov/~paterno/images/effic.pdf>

    The ROOT library's website: <http://root.cern.ch>

AUTHOR
    Author of the Perl glue code is Steffen Mueller, <smueller@cpan.org>.

    Author of the method of calculating the confidence intervals and its
    implementation is Marc Paterno.

COPYRIGHT AND LICENSE
    Copyright (C) 2011 by Steffen Mueller

    Most of the code is taken from the ROOT library (licensed under LGPL)
    and by proxy, the CEPHES library (licensed with a modified BSD license).
    The full list of ROOT authors can be found on the ROOT website
    <http://root.cern.ch>.

    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU Lesser General Public License (LGPL). You can
    find a full copy of the license in the LICENSE file in this
    distribution.

