Re: regarding accuracy of fit

[John Swensen]

On Jul 18, 2011, at 12:18 PM, preeti gaikwad wrote:

> Hello, PLease help me to calculate the accuracy of the fit? suppose I have 
> the value of y from the experimental data and value of f from the fit now I 
> want to know the best fit?
> 
> I am doing that suppose R=y-f;
> and then ploting R with x values this is giving the correct result but I HAVE 
> TOO much data to handle so I am getting a fluctuation with straight line??? 
> not getting what tto do??
> thanks in advance for help 
> 

I don't quite understand what you are asking.  Here R is the residual for the 
fit.  However, you haven't mentioned what you are using as a model for the 
function f.  Is your question how to determine what model to use?  Do you want 
to know how to pick the order of a simple polynomial fit of your data that 
minimizes residuals?  There isn't enough information given in your email to 
know exactly what you are trying, but a good place to start would be to read 
the Wikipedia article on overfitting
http://en.wikipedia.org/wiki/Overfitting

If you let us know a little more about what you are trying to do, it would help.

John Swensen