Ratio plot problem

ROOT
1

Hey All,
I am trying to plot ratio of two normalized histograms. But problem is number of entries in the individual histograms is more compare to the ratio qinv_new qinv_ratio
Please suggest how to resolve this problem,histogram_qinv.cpp (1.1 KB)
Thanks in advance .

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2

I don’t understand the problem. Could you reformulate it?

Is it correct that the bottom plot shows red/blue?

3

Thanks for your response. Yes I was trying plot red/blue. But if you look number of entries in individual histograms are 324707. But in the ratio plot entries are 54 and also distribution is not as expected.

4

I think it has 54 entries because the histogram has 54 bins (maybe check if that’s true).

Why is the distribution not as expected? It’s high where the histograms differ a lot, and it goes towards 1 / below 1 where the histograms cross. That look correct to me.

5

Just to check, I tried one more times. For both histograms having bin number 50 and ranging from 0 to 120.same_Delta_pT

And ratio plot looks like:
Delta_pT_new

Now here number of entries in ratio plot 2389.
I used same macro which I attached.

6

Ok, the ratio plot looks perfect, only the number of entries is interesting.

I looked in the code as to what happens with the entries:
It computes the number of effective entries from the sum of weights in the histogram. The weights, in turn, depend on bin contents and bin errors.

7

Thank you so much for your remark. So are there any suggestion on the same?

8

No suggestions. What else do you need?

  • The ratio is OK
  • The entries try to give the best number of how much effective statistical uncertainty the histogram has.

I don’t see how you could do better.

If you really want, you can set the entries manually, but I cannot think of anything that’s better than what you already get.

9

Thank you so much. Yes now it is enough what I expected.

10

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