Get the CLs for a fixed PoI

Roofit and RooStats
1

Dear experts.

When we do p-value vs. PoI scanning, for each PoI value, we can call the function as in below to get the CLs value:
HypoTestInverterResult * r;
val = r->CLs(index);

I have two simple questions:

  • this val is expected or observed CLs ? If it is observed, then how to get the expected ?
  • still for this PoI, how to obtain the ± 1/2 sigma expected CLs numbers ?

Thanks!
Javier

2

Hi Javier,

As written in the documentation CLs returns the observed CLs value. To obtained the expected one (including
the +/- 1 sigma), you need to compute using the median and the quantiles of the expected p-values distributions available for each poi point.
You obtained the expected p-values distribution from HypoTestInverterResult::GetExpectedPValueDist(index)

The code example doing this is in root.cern.ch/doc/v606/HypoTestI … tml#l00120

from line 163 to 200

Best Regards

Lorenzo

3

Dear Lorenzo,

Thanks a lot! Your method works.

Regards,
Javier