# Parameter for RooPlot::chiSquare

Dear RooFit experts,
I have a very simple question about the method chiSquare of RooPlot.

Data of the problem:

• 1 dimensional fit
• p.d.f. with 2 free parameters
• we perform an extended maximum likelihood fit

when I call chiSquare(N) what value shell I give to N ?

I was thinking to give the value N = 2 + 1 - 1 = 2
2 +1 = number of free parameters of the p.d.f. (the + 1 comes from the fact we are doing an extended maximum likelihood fit)

• 1 comes from the fact that we have one independent variable (i.e. one dimensional fit)

Is this correct ?

Thanks,

• Mauro.