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I would like to exponentiate the values of independent variables in a regression model, possibly using splines. I know that collinearity between X and X^2 is to be expected and the standard remedy is to center by taking X-average(X) prior to exponetiating. This seems odd to me because it will change the shape of the relationship between X and X^2 to one that is U-shaped, not monotonic. For example, if after centering you have

-2

-1

0

1

2

then the formerly lowest value will now be equal to the highest when squared. This seems to disrupt the idea that lower values have a lesser effect, lets say. What am I not getting that makes this make sense to do? Thanks. Seth

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# Centering to reduce collinearity of x^2?

**Physics Forums | Science Articles, Homework Help, Discussion**