How to predict furure values in a non linear regression?

Hi, I have a set of data and using the cftool I create a fitting curve of third order.

Now I want to predict future data using this fitting curve but I don't have any idea to do this.

[KSSV]

future data? Do this future data lie in the intervel of input?

Answer 1

[Torsten]

Naive procedure:

If your fitting curve depends on time t, evaluate it at the future time instant you have in mind.

But be very,very careful here:

Extrapolation of trend curves is extremely error-prone. Especially polynomial curves of degree greater 1 usually don't reflect the physical or economical background where the data stem from and are therefor only suited to interpolate between the time limits of your data.

[FEDERICO CIOL]

My curve fitting has on y-axis the RMS value and in x-axis there is the index of the RMS from excel file.

But, in practice how i can evaluate it? I have to use a particular tool?

[Torsten]

Didn't you get a formula for the polynomial p as

p(RMS index) = RMS value

(whatever RMS may mean)

?