Vector Psychometric Group has acquired Scientific Software International, Inc.

Vector Software Acquisition, a sole subsidiary of Vector Psychometric Group, acquired Scientific Software International, Inc. expanding Vector’s statistical software offerings.

Vector Psychometric Group (VPG), a leading provider of psychometric and data analytic solutions for clinical outcomes, educational, and psychological assessment, has acquired Scientific Software International, Inc. (SSI), a market-leader in statistical software for social, behavioral, and biostatistical sciences.

SSI has been developing, publishing, and distributing specialized statistical software products since 1971. SSI has been a driving force behind many widely used statistical software packages, which includes HLM® and SuperMix® for multilevel modeling; BILOG-MG®, PARSCALE®, and IRTPRO® for item response theory modeling; and LISREL®, the progenitor of structural equation modeling.

Jointly VPG and SSI provide nearly 60 years of statistical software development experience. This combined experience will allow the companies to expand their current software capabilities, rejuvenate existing products, and build on their long history of advancing the psychometric and behavioral analytic sciences through software.