HEC-SSP is designed for interactive use in a multi-tasking environment. The system is comprised of a graphical user interface (GUI), separate statistical analysis components, data storage and management capabilities,
mapping, graphics, and reporting tools.
Over a period of many years, HEC has supported a variety of statistical packages that perform frequency analysis and other statistical computations. Historically, the programs that received the most use within USACE
were HEC-FFA (Flood Frequency Analysis) and STATS (Statistical Analysis of Time Series Data). HEC-FFA incorporates Bulletin 17B procedures that are used for flow frequency analysis. The STATS software package is used
for statistical analysis of time series data. STATS can provide either analytical or graphical frequency analysis, specified by the user. STATS has the capability of computing monthly and annual maximum, minimum, and
mean values along with computing a volume-duration analysis. Two other packages that have received a lot of use within USACE are REGFRQ (Regional Frequency Computation) and MLRP (Multiple Linear Regression Program).
REGFRQ performs regional frequency analysis and MLRP is a multiple linear regression analysis tool.
The goal of HEC-SSP is to combine all of the statistical analyses capabilities of HEC-FFA, STATS, REGFRQ and MLRP while advancing the realm of statistical hydrology through cutting-edge techniques (such as the use of
the Expected Moments Algorithm).