# Hello,I have an analytical expression E$_{i}$ that I

1. Dec 16, 2011

### kassem84

Hello,

I have an analytical expression E$_{i}$ that I want to fit it to some data E(Ref)$_{i}$ . I fitted this expression for N-points:
I have calculated the value of chi-squared using the following formula:
$\chi^{2}$=$\frac{1}{N-1}\sum_{i=1}^{N}\frac{(E_i-E(Ref)_i)^{2}}{σ_{i}^{2}}$

where:
σ$_{i}$=error*E(Ref)$_{i}$

Normally, I took the error =3-5%, and I got values of $\chi^{2}$=0.01

Is this value reasonable? How can we judge on the values of $\chi^{2}$?