# Problem in error calculation in TH1::Divide after Scale

Dear all,
i’m in trouble to get correct erros using Divide on scaled histograms.
i get bin errors as they were in the un-scaled case.
Attached a simple macro to reproduce this.
running scale_errors.C you will get 10 bin errors for un-scaled case
as they are from histogram (bin) and calculated from binomial stat (calc).
Then same thing for scaled histograms with factor 100
As you can see errors from divided histograms are as before while, of course, those calculated with formula are lower.

Any hint ?

Many thanks,
Max
scale_errors.C (1.03 KB)

Dear Max,

scaling an histogram is just multiplying the error and content by a constant number and it is not like increasing its statistics. Therefore the bin errors resulting from the division of two histogram are correctly not expected to change.

Best Regards

Lorenzo