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Road map, and Tutorials (let me know what you’d like, or perhaps a book?)

umx is a package designed to make structural equation modeling easier, from building, to modifying and reporting.


You should cite: Timothy C. Bates, Michael C. Neale, Hermine H. Maes, (2019). umx: A library for Structural Equation and Twin Modelling in R. Twin Research and Human Genetics, 22, 27-41. DOI:10.1017/thg.2019.2

umx includes high-level functions for complex models such as multi-group twin models, as well as graphical model output.

Install it from CRAN:


Most functions have extensive and practical examples (even figures for the twin models): so USE THE HELP :-).

See what is on offer with ‘?umx’. There are online tutorials at

umx stands for “user” OpenMx functions. It provides over 100 functions, but most importantly:

  1. umxRAM that makes path-based SEM in R straightforward, with umxSummary and plot for table and graphical display of your models. It can also interpret basic lavaan if you get a script in that language.
  2. A suite of twin modelling functions, such as umxACE.

These are supported by many low-level functions automating activities such as parameter labels, start values etc., as well as helping with data-wrangling, journal-ready presentation (try umxAPA() among other tasks.

Some highlights include:

  1. Building Path Models
  2. Reporting output
  3. Modify models
  4. Twin modeling!
  5. Easy-to-remember options
  6. Many more miscellaneous helpers e.g.

Code and requests welcome via Github. Tell your friends! Publish good science :-)

For thrill-seekers and collaborators only: the bleeding-edge development version is here: