Copyright © 2007-2017 The OpenMx Project
The OpenMx project was originally funded through the Interdisciplinary Program  of the National Institutes of Health Roadmap  initiative. It is now funded through research grant DA-018673 from NIDA . We currently have 14 core team members and 25 core beta testers located in 5 countries and 23 academic institutions. The web page is hosted and maintained by the Social Science Research Institute  and Quantitative Developmental Systems group  at Penn State . Pre-built package binaries are hosted by the Human Dynamics Lab  in the Department of Psychology  at the University of Virginia . The project is licensed under the Apache License, Version 2.0 .
In the late 1980s, Steve Boker and Jack McArdle wrote some software for the analysis of path models called Rampath. In 1990, Michael Neale began writing the SEM package Mx . In the early 90s, Michael Neale and Steve Boker merged the Rampath algorithm into Mx  and a strange monster was born: the MX GUI. People could point and click their way through building a path model in a front end and numerical estimates for the model would be produced by a back end. This architecture worked well enough that the basic premise has survived to this day and is used by OpenMx which has a front end in the R statistical software and a backend optimizer written in C. In some ways, Mx  is barely recognizeable in OpenMx since the interface is completely different and the software has been rewritten top to bottom using modern programming techniques and languages. But deep within OpenMx still beats the ancient heart of Mx : a general purpose matrix optimization package. As time goes by, we expect you will be surprised at all of the things that OpenMx can do.
mxStandardizeRAMpaths(), aficionado of analytic derivatives and custom fitfunctions
What's the deal with the Guinea Pig?
The first published path diagram was in Sewell Wright's 1920 article, "The relative importance of heredity and environment in determining the piebald pattern of guinea–pigs." Proceedings of the National Academy of Sciences, 6, 320–332. Believe it or not, Wright used drawings of guinea pigs rather than circles or squares to represent his variables. Here is a reproduction of the original diagram.
Our logo came from the Open ClipArt Library .