Question about error from TFractionFitter

[moneta]

Hi

This is a known problem of TFractionFitter, there is a note written some time ago, see
[0803.2711] A pitfall in the use of extended likelihood for fitting fractions of pure samples in mixed samples. Figure 1 in the note illustrates well the problem.

See as well the discussion in

TFractionFitter Errors

Hello, I am currently trying to use the TFractionFitter to extract signal and background components from a pseudo data histogram. But somehow, the pull distributions have a sigma, which is less than one, thus showing that the errors are bigger than expected. I tried to make the fit easier by using two Gaus functions, but still the same problem remains. So in my script I produce two Gaus functions to create signal and background histograms, where I also draw pseudo data from the histograms for…

Lorenzo