Usage of Rho_A reliability coefficient

Questions about the implementation and application of the PLS-SEM method, that are not related to the usage of the SmartPLS software.
Post Reply
Brusset_X
PLS Junior User
Posts: 9
Joined: Tue Feb 19, 2013 4:05 pm
Real name and title:

Usage of Rho_A reliability coefficient

Post by Brusset_X »

Hi everyone,
I would like to use the rho_A coefficient as defined in Dijkstra and Henseler(2015) and implemented in PLS3.2.
In a small model with 4 reflexive constructs, I have both rho_A and sqrt(rho_A) in the tables as implemented by PLS3.2. The above reference does not give an idea of the threshold under which a rho_A indicates that a LV is not reliable. And what use does sqrt(Rho_A) have?

One key LV which is causing me headaches has 8 items, a Cronbach alpha of .705, a composite reliability of 0=.403 and a rho_A of .647. How do I analyze such results? Pruning the items only makes things worse (at least regarding the alpha).

All path coefficients leading from it are t-statistics <1.96, meaning that it does not have any effect on the other LV.
BTW, all the other LV have nice and healthy reliability and discriminating coefficients.

Any help appreciated.
Thanks.
Xavier Brusset
Professor
Logistics and supply chain management
Toulouse Business School
User avatar
Hengkov
PLS Super-Expert
Posts: 1599
Joined: Sun Apr 24, 2011 10:13 am
Real name and title: Hengky Latan
Location: AMQ, Indonesia
Contact:

Re: Usage of Rho_A reliability coefficient

Post by Hengkov »

Hi Xavier,

That I remember the cut-off value of coefficient Dijkstra-Henseler Rho_A must be > 0.7 as Composite Reliability.
If you do not want to remove the item, you may have to give a little justification there.

You also need to see the value GoF with SRMR and NFI, I think you are a bit of a bad fit model.

Best regards,
jmbecker
SmartPLS Developer
Posts: 1282
Joined: Tue Mar 28, 2006 11:09 am
Real name and title: Dr. Jan-Michael Becker

Re: Usage of Rho_A reliability coefficient

Post by jmbecker »

Hi Latan,
can you provide a reference that explains how to calculate the NFI for PLS models?
Dr. Jan-Michael Becker, BI Norwegian Business School, SmartPLS Developer
Researchgate: https://www.researchgate.net/profile/Jan_Michael_Becker
GoogleScholar: http://scholar.google.de/citations?user ... AAAJ&hl=de
Brusset_X
PLS Junior User
Posts: 9
Joined: Tue Feb 19, 2013 4:05 pm
Real name and title:

Re: Usage of Rho_A reliability coefficient

Post by Brusset_X »

Hi Latan,
Thank you for the reply. I have looked at the Dijkstra Henseler reference and they don't mention a cut-off value for Rho_A. If I look at the SRMR given by SmartPLS3.2.3, I get a SRMR for common factor of 0.079 and SRMR for the composite model of 0.053. Are these good values?

Would you mind giving a reference on how to evaluate these criteria for model fit? Also, you speak of NFI. I thought that NFI was purely for SEM-ML models, ie, LISREL AMOS type models.

Can you please substantiate how such an index can be calculated in PLS?

Thank you for your time and patience.

Regards.
Xavier
Xavier Brusset
Professor
Logistics and supply chain management
Toulouse Business School
lpfeil
PLS Junior User
Posts: 2
Joined: Tue Jul 03, 2018 9:06 am
Real name and title: Lisa Pfeil

Re: Usage of Rho_A reliability coefficient

Post by lpfeil »

Hi everyone,

Does anybody know what a Rho_A value above 1 means and how to interpret it?

Best regards,

Lisa
User avatar
cringle
SmartPLS Developer
Posts: 818
Joined: Tue Sep 20, 2005 9:13 am
Real name and title: Prof. Dr. Christian M. Ringle
Location: Hamburg (Germany)
Contact:

Re: Usage of Rho_A reliability coefficient

Post by cringle »

A rho_A value above 1 is strange and should not occur. You may revert to Cronbach's alpha in that case.
jmbecker
SmartPLS Developer
Posts: 1282
Joined: Tue Mar 28, 2006 11:09 am
Real name and title: Dr. Jan-Michael Becker

Re: Usage of Rho_A reliability coefficient

Post by jmbecker »

It may also indicate that you do not have a valid factor model. A composite model might be better in your case. You should re-consider and re-evaluate your measurement approach.
Dr. Jan-Michael Becker, BI Norwegian Business School, SmartPLS Developer
Researchgate: https://www.researchgate.net/profile/Jan_Michael_Becker
GoogleScholar: http://scholar.google.de/citations?user ... AAAJ&hl=de
Tonka
PLS Junior User
Posts: 8
Joined: Mon Oct 19, 2020 2:47 pm
Real name and title: Antonija Petrlić, MBA

Re: Usage of Rho_A reliability coefficient

Post by Tonka »

Dear,
what if rho_a (for all indicators) is higher than CR?
Cronbach's are for all indicators are smaller than rho_A.
Post Reply