Q2

Feel free to post your requests for new SmartPLS features and other suggestions.
Post Reply
sellitto
PLS Junior User
Posts: 1
Joined: Sat Oct 30, 2010 12:41 am
Real name and title:

Q2

Post by sellitto » Thu Sep 07, 2017 3:52 pm

Dear friends:
In calculating the predictive relevance of an endogenous reflective construct, we must calculate Q2. In the book, Hair et al. (2017, p. 207) state that zero values and below have no predictive relevance. I ask: If Q2 is a square, can Q2 reach a value below zero? Is there something wrong or Q2 doesn't mean a square?
Best Regards
Professor and researcher in Industrial and System Engineering

jmbecker
SmartPLS Developer
Posts: 842
Joined: Tue Mar 28, 2006 11:09 am
Real name and title: Dr. Jan-Michael Becker

Re: Q2

Post by jmbecker » Thu Sep 07, 2017 6:53 pm

The name Q² might be a little bit confusing as it is not a real square. In contrast to the R² it is also not bound between 0 and 1. Yet, it has some similarities to R² and that is probably the origin of its name. It is calculated as 1-(SSE/SST), where SSE is the sum of squared errors and SST is the total sum of squares. In contrast to the R² the SSE is based on the prediction error and this prediction error can be smaller or larger than the SST (which would be a prediction using the mean). Hence, you can have negative and positive values for Q².
Dr. Jan-Michael Becker, University of Cologne, SmartPLS Developer
Researchgate: https://www.researchgate.net/profile/Ja ... v=hdr_xprf
GoogleScholar: http://scholar.google.de/citations?user ... AAAJ&hl=de

Post Reply