RooStats, MCMC Calculator doesn't not work

I did tutorial summarized in here,

and I did exercise
[ Exercise 5: Compute a 95% Upper Limit with the Counting Model ]

But, MCMC Calculator defined in web page does not work …
in contrast, Profile Likelihood Calculator seems to work.

(why I can not upload files here…)
the files I copied is here,

My ROOT version is ROOT6.14/00

Hi @ToMu; I am sure @moneta can help you with this.


It seems he is an author of the files?

just comment on Exercise 5
it works for Gaus + Exp model, this is fine.
but, it doesn’t for “Poisson model with signal and background”

still waiting …

@moneta ping!

Hi ,
Sorry for the late reply. It is possible the MCMC calculator needs some thing to make it work with a specific model.
Your links for the files you have posted (corrected for an extra character)
Download from - send big files the easy way have a code example using the BayesianCalculator not the MCMC one.
Do you have problem with the Bayesian calculator or the MCMC one or with both ?



The problem you have in the linked script is in this line:

par.setRange(par.getVal()-10*par.getError(), par.getVal()+10*par.getError()); 

Here you are setting a range for the nuisance parameters that is needed when using a Bayesian tool, since we integrate on them.
Now, since you are not performing first a fit to your model, you should maybe selected a fixed range looking at your specific input model. In your case you can easily assume that b can be limited for example between [0,5].
So you can change that line to:


and your macro will work fine


Dear ROOT experts, moneta, eguiraud, and jalopezg.
Thank you for the remind, reply and comment.
I will try to follow your comments and test it quickly!!
Best regards.

P.S. it works, I try to understand the framework and statistics itself !

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