1. Error treatments.
- 3 ways to treat your errors: uncorrelated, binomial, Bayesian Asymmetric
Tutorials: http://nuclear.ucdavis.edu/~cflores/protected/LFSpectraTutorials/ also in here
reference:  http://arxiv.org/abs/physics/0701199
--- Contributed by Chris Flores

2. Error for fit.
Example: fitEff.C
Function IntegralError() is quite useful for calculating the error of the fit in certain range.