CDF Statistics Committee -
There are a number of software tools that have been developed
to perform certain types of statistical calculations. We list the
ones that we have "qualified" below:
- POILIM was the "standard" tool used by the CDF Exotics
group in Run 1 to set confidence level limits in single-channel
counting experiments. Its use is no longer recommended: it is
unable to be extended to multiple channel or multibin analyses.
Nevertheless, it is described in
CDF Note 4476.
- BAYES, available at bayes.f,
calculates upper limits using a Bayesian method with
flat prior probability. It does not allow you to combine
channels or take into account correlations, etc. For a method
which does these things, see
CDF Note 6428.
CDF Note 7117, the first in a series of planned notes
comparing various methods of setting limits in the presence of
nuisance parameters, implements a Bayesian approach. The
associated software (written in C) is available as the
Links to individual
functions and a brief user guide
are also provided.
- CDF Note
7587 presents an approach to calculating Bayesian limits in a
more general case, with multiple channels whose acceptance and
background priors are modeled via Monte Carlo. This strategy
permits correlations between the various acceptance and background
priors (e.g. between channels). The software (also written in C) is
available as the tarball
to individual functions
are also provided.
- Tom Junk has provided
code for ROOT
that can compute limits using the CLs method and also interfaces to
the Bayesian genlimit code described above. This is documented
in CDF Notes 8128
It includes useful tools for
organizing histograms, nuisance parameters, and interpolations as
an input to the tools in genlimit. The
Bayesian limit calculations is a common use of the package
(the CLs limits it also calculates are typically
much more computationally intensive and give roughly the same
answers in typical cases). The package can also compute p-values.