Higher order polynomial trendlines in Excel
Higher order polynomial trendlines in Excel
(OP)
HI all,
Is it possible to have higher order polynomial trendlines (i.e. higher than 6) in Microsoft Excel? If not, are there any free apps I can use for the purpose.
Thanks.
Is it possible to have higher order polynomial trendlines (i.e. higher than 6) in Microsoft Excel? If not, are there any free apps I can use for the purpose.
Thanks.
RE: Higher order polynomial trendlines in Excel
Good luck,
Latexman
RE: Higher order polynomial trendlines in Excel
If you feel you need to resort to a high-order polynomial, your data might actually be telling you that a polynomial is not appropriate. You might be better off fitting some different form of curve - reciprocal, exponential, etc - or even a combination of these. The resulting curve fitting cannot be done automatically within Excel, but it is not difficult. By laying your data out in an appropriate manner you can set up a cell that contains the sum of the squares of the errors for any particular set of parameters for the hypothesized relationship. You can then use the Solver to search for the set of parameter values that minimizes this sum of the squares of the errors.
Also, look very hard at your data, and ask yourself if there are any a priori reasons for expecting any particular behaviours (such as asymptotes), even if these behaviours will not significantly manifest themselves within the range of your data points. If so, select a form of curve that honours these behaviours.
HTH
RE: Higher order polynomial trendlines in Excel
m777182
RE: Higher order polynomial trendlines in Excel
I finally found a way to represent my curves as fourier series equations (by setting up composite tables in Excel) rather than polynomials and have a much better approximation. The area under each curve was also obtained using approximate integration methods.
Thanks a lot for your contributions.
Kokonut