JeffreysPriorDemo example: working?

Roofit and RooStats
1

Dear all,
I am using root 6.16 and I wanted to investigate Jeffreys Prior.
I ran the example called JeffreysPriorDemo.C in this way:

root [0] .L JeffreysPriorDemo.C+
root [1] JeffreysPriorDemo()

and the canvas I get is in attachment.JeffreysPriorDemo.pdf (14.0 KB)
Is this expected, please?

I have also tried the other functions in the example (TestJeffreysGaussMean,TestJeffreysGaussSigma,TestJeffreysGaussMeanAndSigma) and the plots I get are similar: it seems there are non zero values are the upper and lower limit of the range.

Any help will be greatly appreciated.

Regards,
Marco Bomben

2

${ROOTSYS}/tutorials/roostats/JeffreysPriorDemo.C

3

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5

Hello,

the problem is as follows:
The JeffreysPrior class internally has to run a fit to extract the fisher information matrix. This does not work if the observable is at its limit.

The solution is simple: Plot in a smaller range.

   RooPlot *plot = w.var("mu")->frame(RooFit::Range(2, 190));

I will add this to the tutorial, and also make the class warn about boundary problems.

6

Thanks a lot Stephan!
Regards,
Marco Bomben