Cutting edge software. Empowering research since 1971.

SSI Live™ Subscription

Meet our new product delivery and support system. Compare with old licensing model.

Hierarchical Modeling

For more than 3 decades, HLM has defined the practice in modeling hierarchical data.

Structural Equation Modeling

LISREL is the progenitor of structural equation modeling, since 1976.

Item Response Theory

BILOG-MG and PARSCALE have enabled IRT applications in educational measurement.

Mixed Modeling

SuperMix offers advanced linear and nonlinear mixed effects modeling for biostatistics.

Growth Modeling

Fast, comprehensive analysis of longitudinal human growth data with Auxal.

Fixed effects, random coefficients, and centering

Steve Raudenbush, Lewis-Sebring Professor of Sociology, Chairman of the Committee...

Remembering Professor R. Darrell Bock

It is with great sadness that we acknowledge the passing...

Updated version of HLM 8.2

SSI is pleased to announce an update to HLM 8.2....