I am making 2D TEfficiencies to model trigger efficiency and I see what I would have thought is weird behavior when plotting them. When I try to plot the 2D TEfficiency in the TBrowser (using the draw option e) I get the following plot:
Where what seems weird to me is that the up uncertainties go above 1 and the down go below 0. It was my understanding that statistical uncertainties and the efficiency of each bin is bounded by [0,1] (i.e. even the efficiency + uncertainty up is bounded by 1). Is this expected behavior?? Or did I do something wrong. I am attaching a minimal reproducer and necessary rootfiles. Thanks!
triggerFiles2Dv7.zip (147.8 KB)
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_ROOT Version: 6.22/07
_Platform: Linux (Ubuntu 20.04 and SLC7)
Compiler: Not Provided
I guess @moneta can help you
This is a limitation of the 2D TEfficiency. We don’t have in ROOT a 2D graph with asymmetric errors, so we cannot draw asymmetric errors bars for 2D objects. When using the option
E for drawing the TEfficiency object you are just using sqrt(content) as errror. You should not use it and instead get the desired error calling
Thanks for the clarification. We did code up a work around using the TEfficiency::GetEfficiencyErrorLow/Up methods but our confusion was that it didn’t match this plot. I see now that it shouldn’t. Thanks!
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