Could anyone guide me on how can we measure the curvature of nonlinear models?

I have to know the methodology to measure nonlinearity (both intrinsic and parametric) for nonlinear regression model. For example, if we have the nonlinear model y = f(x)+e then how we can say which type of nonlinearity exists and what is the degree/amount of nonlinearity in the given model?

  • $\begingroup$ Are you only interested in the bivariate situation, so one x and one y, or in a multiple x situation? For the former take a look at distance correlation, maximum correlation or the maximum information coefficient. $\endgroup$
    – Momo
    Mar 14 '15 at 12:08
  • $\begingroup$ thanks .i am interested in multivariate case.I want to know the method how to calculate degree of nonlinearity $\endgroup$
    – zahid khan
    Mar 15 '15 at 12:46