PSPP is a program for statistical analysis of sampled data, and is a free replacement for the proprietary program SPSS. PSPP can perform descriptive statistics, T-tests, linear regression and non-parametric tests. Its back-end is designed to perform its analyses as fast as possible, regardless of the size of the input data. You can use PSPP with its graphical interface or the more traditional syntax commands. Some benefits are that PSPP uses SPSS files and is compatible with OpenOffice and can support 1 billion data observations.