**Geant4 Test & Analysis** is a project to develop a system for**
statistical testing.**

The main application areas in Geant4 are **physics validation**, **regression testing** and **system testing**.

The project develops tools to compare Geant4 simulation results with reference data, which can be:

- equivalent reference distributions
*(for instance, comparison of two histograms in regression testing)*
- experimental measurements
- data libraries from reference distribution sources
- functions deriving from theoretical calculations or from fits

Thanks to the adoption of a component-based architecture and of standard interfaces for data analysis (AIDA),
the project can be of interest to a wider scope than Geant4. Clients may use one or more components, without being bound to the
whole system, or to Geant4-specific features.

The core statistical component is designed to be generally applicable to the
problem of comparing two data distributions, independently from their origin or the context (i.e. not limited to Geant4).

#### Statistics component

The core statistical component is meant to provide an ample set of **goodness of fit
**tests *(chi squared, Kolmogorov-Smirnov, Cramer-von Mises, Anderson-Darling etc.)*, appropriate to the comparison of
various kinds of distributions *(binned, unbinned, continuous, multi-dimensional, affected by experimental errors etc.).*

#### Physics Testing component

A set of tests, providing physics distributions to be compared to reference data, complements the
project. An overview of physics results
and of regression test results is
available.

In the first phase of the project the tests focus on Geant4 Electromagnetic Physics.

*Last modified 18 May 2003 - Maria
Grazia Pia*