Errors in ratio histogram are coming large

Hi,
Could someone please help me understand why the vertical bars in data/MC ratio at the bottom plot is coming large than required?

 // mc is the MC histogram as shown in the upper pad while data is the histogram shown in the upper pad.
 // Following lines I write in bottom pad:
 mc->Scale((data->Integral())/(mc->Integral()));//To normalise MC to data
 data->Divide(mc);
 data->Sumw2();
 data->Draw("ep")

image

Thanks a lot!


_ROOT Version:5.34
Platform: Not Provided
Compiler: Not Provided


Hi,

I think you should have called the
data->Sumw2();
before the
data->Divide(mc);
, not after.

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