Archive for the ‘General News’ Category

OpenMx 2.0: Extended Structural Equation and Statistical Modeling

Thursday, November 6th, 2014

Neale, M.C., Hunter, M.D., Pritikin, J.N., Zahery, M., Brick, T.R., Kirkpatrick, R., Estabrook, R., Bates, T.C., Maes, H.H., & Boker, S.M.; (in press) OpenMx 2.0: Extended Structural Equation and Statistical Modeling. Psychometrika

The new software package OpenMx 2.0 for structural equation and other statistical modeling is introduced and its features are described. OpenMx is evolving in a modular direction and now allows a mix-and-match computational approach that separates model expectations from fit functions and optimizers. Major backend architectural improvements include a move to swappable open-source optimizers such as the newly-written CSOLNP. Entire new methodologies such as Item Factor analysis (IRT) and State-space modeling have been implemented. New model expectation functions including support for the expression of models in LISREL syntax and a simplified multigroup expectation function are available. Ease-of-use improvements include helper functions to standardize model parameters and compute their Jacobian-based standard errors, access to model components through standard R $ mechanisms, and improved tab completion from within the R Graphical User Interface.

The manuscript of this article accepted for publication can be downloaded as a PDF. This article may not exactly replicate the final version published in Psychometrika. It is not the copy of record.

Modular Open-Source Software for Item Factor Analysis

Wednesday, November 5th, 2014

Pritikin, J. N., Hunter, M. D., & Boker, S. M. (2015) Modular Open-Source Software for Item Factor Analysis. Educational and Psychological Measurement 75:(3), 458-474

This paper introduces an Item Factor Analysis (IFA) module for OpenMx, a free, open-source, and modular statistical modeling package that runs within the R programming environment on GNU/Linux, Mac OS X, and Microsoft Windows. The IFA module offers a novel model specification language that is well suited to programmatic generation and manipulation of models. Modular organization of the source code facilitates the easy addition of item models, item parameter estimation algorithms, optimizers, test scoring algorithms, and fit diagnostics all within an integrated framework. Three short example scripts are pre- sented for fitting item parameters, latent distribution parameters, and a multiple group model. The availability of both IFA and structural equation modeling in the same software is a step toward the unification of these two methodologies.

The manuscript of this article accepted for publication can be downloaded as a PDF. This article may not exactly replicate the final version published in Educational and Psychological Measurement. It is not the copy of record.

OpenMx Enters Public Beta Testing

Wednesday, October 7th, 2009

OpenMx entered public beta testing on October 8, 2009. The OpenMx website is now accepting self-registration. Go to the website, register, login, and download the most advanced free and open source Structural Equation Modeling package available. Registration also allows posting access to the OpenSem forums. Let us know what you think!

OpenMx is made possible by a Roadmap Initiative grant from the National Institutes of Health

OpenMx Software Begins Beta Testing

Tuesday, August 4th, 2009

The first beta test for OpenMx began today as the software was released to the first 16 beta testers some twenty months after the project began. OpenMx is free and open source structural equation modeling (SEM) software for use with the statistical software R. The project is led by Steven Boker and currently includes 14 core developers at UVa and other universities such as Virginia Commonwealth University, University of Chicago, University of Houston, McMaster University, and University of Edinburgh. The open source project currently is comprised of over 25,000 lines of code and documentation. OpenMx will begin public beta testing in October.

Learn more about the OpenMx software, documentation, and forums at the OpenMX web site.

Local television

Monday, May 11th, 2009

Members of the Human Dynamics Laboratory were interviewed today by the local CBS, ABC, and Fox affiliate about their High-Presence, Low-Bandwidth, Apparent 3D Video-Conferencing system.  The article and video can be seen here.