Welcome to Jose Cortina's website!
I have stepped boldly into the 90's and have created my very own site for the interwebs.
Welcome to Jose Cortina's website!
I have stepped boldly into the 90's and have created my very own site for the interwebs.
About the site
Why
Reviewers keep telling me to spoon feed the readers of my papers so that they don't have to do any work. Thus was born the df calculator, the RV interaction tests, etc. Think of the site as a sort of Gerber's for statistics.
What
Below, you can find
- The myriad examples and tests for restricted variance interactions from Cortina, Kohler, Keeler, & Nielsen (2019; also referred to in Cortina et al., 2023, ETP),
- R code for testing latent variable interactions
- An Excel-based calculator for the Omega coefficients as described in Cortina et al. (2020, JAP)
- Data files and code for endogenous moderator models (Cortina et al., 2023, ORM)
- Various things promised in Craig-Aulisi, Markell-Goldstein, Cortina, Wong, and Foroughi (2025, Psych Methods).
NEWLY ADDED: A TOOLS menu (top right of this page) that will take you to:
- An expanded tool for computing degrees of freedom for SEM models ala Cortina et al. (2017 ORM)
- An omega-h calculator (as recommended in Cortina et al., 2020)
- A recruitment calculator based on Cortina et al. (in press JAP)
- A meta-analysis tutorial, including illustrations of the heterogeneity and publication bias methods described in Kepes, Wang, & Cortina (2023 and 2024)
- An estimator for the Conceptual and Grammatical Redundancy indices developed in Alley et al., (JOM; 2026).
- Visualization tools for some basic correlation/regression models
Who
My CV is down there somewhere.
Pictures
Godaddy has these stock layouts, and some of them require pics. Godaddy's stock pics are lame, so, apropos of nothing at all, we have here the World 1 building in February 2017 and the fountain outside St. Peter's in January 2017 during a record cold snap which, as a matter of course, coincided with my visit. Later, you will be treated to my shadow nailed to the floor of St. Peter's.
We also have pics from Sydney in July, 2019, including pics of the opera house and the harbor bridge at dawn as well as what might possibly be the single best example of topiary in the world.
Then we have pics from Scotland, 2023 (mostly). One will only make sense if you are a Highlander aficionado. One is of our intrepid hero scaling Hadrian's Wall. One represents an object for which I am currently taking donations (Hint: Not the deer). One is my cat (Hint: Also not the deer). In case you aren't fluent in feline, he is saying, "Nice socks dude."
Supplemental Material
Restricted Variance Interactions
We show you how to test them, with examples in several software packages. Go to the Downloads section below for the file that explains RV interaction tests in Excel, SPSS, R, and MPlus.
The papers below explain the nature of RV interactions and provide various examples at all levels of analysis:
Cortina, J.M., Köhler, T., Sheng, Z., Keeler, K.R., Nielsen, B.B., Coombs, J.E., and Ketchen Jr., D.J. (2023). Restricted variance interactions in entrepreneurship research: A unique basis for context-as-moderator hypotheses. Entrepreneurship Theory and Practice.
Cortina, J. M., Köhler, T., Keeler, K. R., & Pugh, S. D. (2020). Situation strength as a basis for interactions in psychological models. Psychological Methods.
https://psycnet.apa.org/doi/10.1037/met0000372
Cortina, J.M., Kohler, T., Keeler, K.R., & Nielsen, B.B. (2019). Restricted variance interactions: What they are and why they are your friends. Journal of Management, 45, 2779-2806. http://journals.sagepub.com/doi/pdf/10.1177/0149206318770735
Cortina, J.M., Kohler, T., & Nielsen, B.B. (2015). Restriction of variance interaction effects and their importance for international business research. Journal of International Business Studies, 46, 879-885. https://doi.org/10.1057/jibs.2015.30
SEM Degrees of freedom calculator
The calculator in the TOOLS menu at the top of the page does the calculations that you need, but this is the link that was mentioned in the actual paper: https://gmuiopsych.shinyapps.io/DegreesofFreedom/
This ShinyR app will allow you to calculate the correct degrees of freedom for a variety of SEM types. The paper below explains the nature of degrees of freedom and shows what they reveal about the use of SEM.
Cortina, J. M., Green, J. P., Keeler, K. R., & Vandenberg, R. J. (2017). Degrees of freedom in SEM: Are we testing the models that we claim to test?. Organizational Research Methods, 20(3), 350-378. https://doi.org/10.1177/1094428116676345
Latent Variable Interactions
The Downloads section contains R code for several procedures for testing latent variable interactions as described in
Cortina, J.M., Markell, H.M., Green, J.P., & Chang, Y. (2021). How are we testing interactions in latent variable models? Surging forward or fighting shy? Organizational Research Methods. https://doi.org/10.1177%2F1094428119872531
A calculator for calculating the elements of the measurement model for a latent product based on values from the additive model can be found at https://georgemasonio.shinyapps.io/ModSEM/ (For some reason, some browsers add several characters onto the end of the hyperlink when you click on it. Just delete them so that all you have are the characters above.)
The omega coefficients
The Downloads section contains an Excel file that computes omega and omega-h using factor loadings and uniquenesses. The virtues of these coefficients relative to those of alpha are discussed in
Cortina, J.M., Sheng, Z., Keener, S.K., Keeler, K.R., Grubb, Schmitt, N., Tonidandel, S., Summerville, K., Heggestad, E., & Banks, G.C. (2020). From alpha to omega and beyond!: A look at the past, present, and (possible) future of psychometric soundness in the Journal of Applied Psychology. Journal of Applied Psychology Monograph, 105, 1351.
By the way, the officious lickspittles at APA, ever on the lookout for superficial solutions to nonproblems, while at the same time being willing to overlook, say, its own efforts to help the Bush administration rationalize its torture program, forbad me from thanking Mike Sturman for his yeoman work as AE on this paper. Well, bugger them. I can thank him here. Thanks Mike, We were very, very lucky that we had you as AE.
Endogenous Moderator Models (EMMs)
The Downloads section contains example data files, SPSS code, and R code for the four types of EMM described in
Cortina, J. M., Dormann, C., Markell, H. M., & Keener, S. K. (2023). Endogenous moderator models: What they are, what they aren’t, and why it matters. Organizational Research Methods, 26, 499-523 10944281211065111.
Gender as a Meta-Analytic Moderator
The downloads section contains an agreement computations file, excel files explaining our simulations, and an example coding file promised in
Craig-Aulisi, Markell-Goldstein, Cortina, Wong, & Foroughi (2025). Detecting gender as a moderator in meta-analysis: the problem of restricted between-study variance. Psychological Methods, 30, 687.
Mostly Scotland
Downloads for Restricted Variance Interactions
Syntax and procedures for testing Restricted Variance Interactions as described in Cortina, Koehler, Keeler, & Nielsen (2019, Journal of Management). The first file explains all of the tests. The other files are the actual Excel files for each example. Godaddy won't let me attach SPSS, R, or MPlus files, but you can transcribe the code from the 'How to test..." file.
HOW TO TEST RV INTERACTIONS (docx)
DownloadBartlett's in Excel (xlsx)
DownloadB-F test in Excel (observed variables) (xlsx)
DownloadB-F test in Excel (hand calculations) (xlsx)
DownloadLevene's test in Excel (observed variables) (xlsx)
DownloadB-F test in Excel for scale scores (xlsx)
DownloadLevene's test in Excel for scale scores (xlsx)
DownloadBreusch-Pagan in Excel (xlsx)
DownloadDownloads for Latent Variable Interactions
Data file and R code for the different procedures for testing latent variable interactions as described in Cortina, J.M., Markell, H.M., Green, J.P., & Chang, Y. (in press). How are we testing interactions in latent variable models? Surging forward or fighting shy? Organizational Research Methods.
Note that the R code is in Word files because GoDaddy won't let me attached R files.
Omega calculator
The input for the calculator is standard output from a factor analysis. Specifically, you need factor loadings and item uniquenesses. Just follow the instructions in the file itself.
omega calculation in excel final (xlsx)
DownloadEndogenous Moderators
dataSet_EMM2 (xlsx)
DownloaddataSet_PartialMediationEMM2 (xlsx)
DownloaddataSet_PartialMediationDirectModerationEMM2 (xlsx)
DownloaddataSet_DoubleModerationEMM2 (xlsx)
DownloadR code for Double Moderation (docx)
DownloadR code for Partial Mediation Direct Moderation (docx)
DownloadR code for Partial Mediation EMM (docx)
DownloadR code for EMM (docx)
DownloadSPSS code for EMM1 (docx)
DownloadSPSS code for Partial Mediation Direct Moderation EMM (docx)
DownloadSPSS code for Partial Mediation EMM (docx)
DownloadSPSS code for Double Moderation EMM (docx)
DownloadCV
Jose Cortina CV (doc)
Download