Thanks a lot Rick for your awesome posts! I have a neophyte question: using a fixed-width kernel on not evenly spaced data (but no serious gap), I must retrieve the coefficients from the local linear approximations for further calculations. I was wondering about the implications of the extension of data with evenly spaced points that you did in order to smooth more. Is it something that I'm also supposed to do, or was it just to improve the appearance of the graph?