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Feb 7, 2014 at 0:11 comment added user39659 orm.sagepub.com/content/15/3/339.abstract To all who come across this in the future, I recommend reading Dalal & Zickar (2012) -- The "solution" of using mean centering is not as straightforward as one would think.
Sep 23, 2012 at 21:35 answer added Peter Flom timeline score: 5
Sep 23, 2012 at 21:25 history edited Peter Flom CC BY-SA 3.0
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Sep 23, 2012 at 19:56 comment added user14316 @Fojtasek I also tried to mean centering the squared X, then I have a positive beta for the normal independent variable and a negative beta for the squared one. That is exactly the case when there is an inverted U-shaped relation, but in that case there is a multicolliniearity problem because the VIF value is higher than 10.
Sep 23, 2012 at 19:39 comment added gung - Reinstate Monica I'm not sure there's a problem here, but if you can provide your data, people may be able to say more.
Sep 23, 2012 at 17:03 comment added Fojtasek I suspect that you squared the mean-centered x instead of mean centering the squared x. If you mean center before you square, you get a u-shaped predictor.
Sep 23, 2012 at 16:40 comment added Michael R. Chernick Is y =ax$^2$ with a>0 the onlt way to get a perfect inverted U? I don't think so. If the inverted U corresponds to a different function then there will not be an a that gives a perfect fit to y=ax$^2$. Then it would be possible for some other model to fit better.
Sep 23, 2012 at 16:19 review First posts
Oct 2, 2012 at 13:02
Sep 23, 2012 at 16:16 history asked atsk CC BY-SA 3.0