RooStat limits

Roofit and RooStats
1

Hi,

I hope this is the right forum for my question:
I am using the ProfileLikelihoodCalculator class to compute an (“observed”) upper limit on the number of signal events, as function of a physical parameter (Higgs mass).
Using the sum of (Standard Model) background processes, I also compute an expected upper limit as function of the physical parameter.

What I would like to do now is to compute +/-1 and +/-2 sigma bands around the expected limit, in order to provide an estimate of how compatible a certain observed upper limit is with the expected value of the limit.

I am wondering if there is a recommended way to compute the +/-1 and +/-2 sigma bands ?

Thank you very much,

Christian

2

Hi,

you can get the expected limits by running Toy MC events and run the ProfileLikelihood on them.
We have an example of this in RooStats a s a tutorial, see
$ROOTSYS/tutorials/roostats/rs503_ProfileLikelihoodCalculator_averageLimit.C

Best Regards

Lorenzo

3

Dear all,

the tutorial mentioned in this thread seems to have disappeared.

$ROOTSYS/tutorials/roostats/rs503_ProfileLikelihoodCalculator_averageLimit.C

Is it not applicable anymore? It is a quite common problem and it would be good to have a tutorial about it.

Best regards,

Tanja

4

Hi Tanya,

the tutorial has been removed since quite some time. You can however still get it from

root.cern.ch/viewvc/trunk/tutori … hrev=31351

Lorenzo

5

Hi Lorenzo,

thank you for pointing me to the tutorial. What was the reason for removing this macro?

Best

Tanja

6

Hi,
the tutorial was sometimes crashing in old RooStats version. Now it should work, and we could probably re-introduce it an updated and improved version.

Lorenzo