LISREL (linear structural relations) is a proprietary statistical software package used in structural equation modeling (SEM) for manifest and latent variables.
It requires a "fairly high level of statistical sophistication".
[1] LISREL was developed in the 1970s by Karl Jöreskog, then a scientist at Educational Testing Service in Princeton, New Jersey,[2] and Dag Sörbom, later both professors of Uppsala University in Sweden.
[4] LISREL is mainly syntax-based, although recent versions have featured a graphical user interface (GUI).
SSI (Scientific Software International) has recently changed from e-Academy to a "home-built" solution for distributing the rental (6- or 12-month) versions of their software.