Hi,
I saw this post on different choices of normalization. It’s a great post.
What I am a little confused about is what should be the ideal label of Y-axis. These few occasions I figured out (I guess), just wanted to confirm. Method-4 gives a histo that is normalized to 1(i.e. the total area), right? Method -6,7 are equivalent and gives (1/N)(dN/dx) as Y-axis. Method-5 gives (dN/dx) as Y-axis. Method-1 gives (dN/dx) as Y-axis, too. Method-3 gives (1/N)(dN/dx) as Y-axis (according to this post) Method-2 I am not at all sure.
So, could you please confirm if I’m getting these wrong or not?
I guess you can just try the various ways and see what you get .
You can also check the documentation of the various
methods used in that post (Scale, Integral …)
Thanks, Olivier for the response.
I actually did that. What I found (comparing the Integrals) is that Method-1, 5 are equivalent, so are Method-2, 4 and Method-6, 7. Am I right?
But, if Method-3 is with Y-axis as (1/N)(dN/dx), what will be the axes for Method-6,7 and also for Method-1,5? For Method-3, I noticed the integral is greater than 1. Below are the plots I got.
Hi,
When normalising an histogram there are two possibilities:
normalize to show frequency probability ( Sum of all histogram bins = 1)
normalize to show a probability density function (Sum of all histogram bins * bin width = 1
The way to do is (and the correct one ) is to use
histo->Scale(1./histo->Integral());
for the first case and
histo->Scale(1./histo->Integral(), "width");
for the second one. The other methods are small variants implementing something similar, and I would forget about them. They could generate confusions and in some case wrong results
