I don't know about SPSS 25 and MPlus, but I would suggest that you take a look at JASP (jasp-stats.org). It is a point-and-click, easy-to-use, open-source alternative to SPSS (with many additional features related to Bayes factor analysis). JASP reads .sav files and under the menu Descriptives > Reliability Analysis you will find Omega statistic. Unfortunately, so far only Omega Total is included (no option to select Hierarchical Omega coefficient), but that might change soon.

Despite your request, I dare to suggest that you take a look at this paper Peters, G. J. Y. (2014). The alpha and the omega of scale reliability and validity: why and how to abandon Cronbach’s alpha and the route towards more comprehensive assessment of scale quality. European Health Psychologist, 16(2), 56-69. It describes step-by-step process on how to use R for this very purpose, starting from how to install R to the very commands you can copy and paste. An easy read.

p.s. The package described in the paper is updated, so when running the same commands you will get calculated not only both types of omega, but also ordinal alpha and omega coefficients together with their confidence intervals.

I don't know about SPSS 25 and MPlus, but I would suggest that you take a look at JASP (jasp-stats.org). It is a point-and-click, easy-to-use, open-source alternative to SPSS (with many additional features related to Bayes factor analysis). JASP reads .sav files and under the menu Descriptives > Reliability Analysis you will find Omega statistic. Unfortunately, so far only Omega Total is included (no option to select Hierarchical Omega coefficient), but that might change soon.

Despite your request, I dare to suggest that you take a look at this paper Peters, G. J. Y. (2014). The alpha and the omega of scale reliability and validity: why and how to abandon Cronbach’s alpha and the route towards more comprehensive assessment of scale quality. European Health Psychologist, 16(2), 56-69. It describes step-by-step process on how to use R for this very purpose, starting from how to install R to the very commands you can copy and paste. An easy read.

p.s. The package described in the paper is updated, so when running the same commands you will get calculated not only both types of omega, but also ordinal alpha and omega coefficients together with their confidence intervals.

There is some exemplary code showing how McDonald's omega can be computed using Mplus in this paper:

http://quantpsy.org/pubs/geldhof_preacher_zyphur_2014.pdf

You can find the code for single level omega in Appendix C, page 3 (cpde for two-level omega, if needed is on page 4):

http://quantpsy.org/pubs/geldhof_preacher_zyphur_2014_supp.pdf

Hope this help.

Best,

Andreas

Hello Marcel,

SPSS doesn't have this (as yet): https://www-01.ibm.com/support/docview.wss?uid=swg21486272

However, the free R library, psych, (among others) does: https://www.personality-project.org/r/html/omega.html

Good luck with your work.

Dear all

many thanks for your contributions. I guessed as much that Omega has not yet been included in SPSS. I will try calculating it in Mplus first and in case this doesn't work I will try JASP.

Best wishes

Marcel

A couple of useful considerations and formulas to adapt even to an Excel spreadsheet:

https://revistas.um.es/analesps/article/view/analesps.33.3.268401/217611