Hi. I've encountered discrepancies between the coefficients shown for a third-order polynomial trendline and those derived using the LINEST() function. The results are identical for a 2nd order polynomial but differ for any higher-order fitting. In similar posts from others experiencing this problem, there always seems to be an explanation (e.g. over-fitting, incorrect cell references and so on). That said, I just can't seem to find my error. Please help!