Hi mates
I have the following two doubts with SmartPLS. I would greatly appreciate your help.
On the one hand... I checked that some items of my model have VIF values higher than 5 and than 10 (some have VIF values of "20" or "30"). I have read that in this case one has to delete the problematic items.
But, what should be process to follow? I think I should delete them step by step, deleting first the item with highest VIF, given that VIF values may change when one of them is deleted.
On the other hand... Item loadings of my model have values < 0.90 and correlations among latent variables are < 0.80. However, discriminant validity is confirmed.
Constructs are conceptually very similar. In fact, some researchers argue that they could be identical. This happen, i.e., with service quality and satisfaction. Both are closely related and I think in this case correlations can be very high.
THANK YOU IN ADVANCE
Doubts: VIF values and high correlations
- 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: Doubts: VIF values and high correlations
Do you try to assess a reflective or formative measurement model? Sounds like a reflective one since you care about the loadings being higher than .7. For reflective measurement models the VIF value is not relevant.
Best
CR
Best
CR
Prof. Dr. Christian M. Ringle, Hamburg University of Technology (TUHH), SmartPLS
- Literature on PLS-SEM: https://www.smartpls.com/documentation
- Google Scholar: https://scholar.google.de/citations?use ... AAAJ&hl=de
- Literature on PLS-SEM: https://www.smartpls.com/documentation
- Google Scholar: https://scholar.google.de/citations?use ... AAAJ&hl=de
Re: Doubts: VIF values and high correlations
Dear Ringle
I'm sorry. Reflective model.
So, VIF values are not relevant? I though I shows care of LV VIF (inner model)?
What about correlations? Higher correlations among constructs (< 0.80) make difficult to guarantee discriminant validity, even being them conceptually different.
Thank you in advance
I'm sorry. Reflective model.
So, VIF values are not relevant? I though I shows care of LV VIF (inner model)?
What about correlations? Higher correlations among constructs (< 0.80) make difficult to guarantee discriminant validity, even being them conceptually different.
Thank you in advance
-
- SmartPLS Developer
- Posts: 1284
- Joined: Tue Mar 28, 2006 11:09 am
- Real name and title: Dr. Jan-Michael Becker
Re: Doubts: VIF values and high correlations
For reflective models you care only about VIFs in the inner model. VIFs in the outer model are allowed to be high.
Are the high VIFs that you report in the inner or outer model?
Your first messages sounds like they appeared in the outer model, because you were talking about deleting "items". You should not delete items because of high VIFs in the outer model for reflective constructs.
If you have high VIFs in the inner model you might check cross-correlations of items and delete those who are problematic. Please also read viewtopic.php?f=5&t=16006
Are the high VIFs that you report in the inner or outer model?
Your first messages sounds like they appeared in the outer model, because you were talking about deleting "items". You should not delete items because of high VIFs in the outer model for reflective constructs.
If you have high VIFs in the inner model you might check cross-correlations of items and delete those who are problematic. Please also read viewtopic.php?f=5&t=16006
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
Researchgate: https://www.researchgate.net/profile/Jan_Michael_Becker
GoogleScholar: http://scholar.google.de/citations?user ... AAAJ&hl=de
Re: Doubts: VIF values and high correlations
Now, I understand everything better. I also checked the other thread. Thank you again. It is helpful to have great professionals in this forum.jmbecker wrote:For reflective models you care only about VIFs in the inner model. VIFs in the outer model are allowed to be high.
Are the high VIFs that you report in the inner or outer model?
Your first messages sounds like they appeared in the outer model, because you were talking about deleting "items". You should not delete items because of high VIFs in the outer model for reflective constructs.
If you have high VIFs in the inner model you might check cross-correlations of items and delete those who are problematic. Please also read viewtopic.php?f=5&t=16006