Hello all
This question might not be proper for this forum.
After fitting(RooFit), I got this message from Minuit.
FCN=4.25237 FROM MINOS STATUS=SUCCESSFUL 857 CALLS 1068 TOTAL
EDM=9.16074e-05 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER PARABOLIC MINOS ERRORS
NO. NAME VALUE ERROR NEGATIVE POSITIVE
1 n_mc3 6.00455e+02 2.69257e+02 -2.72472e+02 2.69813e+02
2 n_spin1 1.57043e+03 2.82148e+02 -4.88650e+02 2.80866e+02
3 n_spin3 2.97256e-06 7.16673e+02 at limit 4.01967e+02
WARNING - - ABOVE PARAMETER IS AT LIMIT.
4 n_spin5 2.15657e-02 6.16212e+03 at limit 4.74591e+02
I set the lower limit to 0 for n_spin3 and n_spin5 because they are the yields for some PDFs.
The values from the fit are at the limit of 0.
I think the parabolic errors for n_spin3 and n_spin5 are meaningless.
How can I get the right errors at the limit?
Thanks in advance.