  RooStats is a project to create advanced statistical tools required for the
analysis of LHC data, with emphasis on discoveries, confidence intervals, and
combined measurements. The idea is to provide the major statistical techniques
as a set of C++ classes with coherent interfaces, so that can be used on
arbitrary model and datasets in a common way. The classes are built on top of
the RooFit package, which provides functionality for easily creating
probability models, for analysis combinations and for digital publications of
the results. We will present in detail the design and the implementation of the
different statistical methods of RooStats. We will describe the various classes
for interval estimation and for hypothesis test depending on different
statistical techniques such as those based on the likelihood function, or on
frequentists or bayesian statistics. These methods can be applied in complex
problems, including cases with multiple parameters of interest and various
nuisance parameters.
