Using the Fit Special option, you can transform Y and X. Transformations include the following: log, square root, square, reciprocal, and exponential. You can also constrain the slope and intercept, fit a polynomial of specific degree, and center the polynomial.
To turn off polynomial centering, deselect the Centered Polynomial check box. See Figure 4.42. Note that for transformations of the X variable, polynomial centering is not performed. Centering polynomials stabilizes the regression coefficients and reduces multicollinearity.