Notes on statistics

In the plot_error_hist() function, the represented uncertainties can be:

  • symmetrical: use the square root of the variance of the histogram

  • asymmetrical: frequentist approach based on a Poisson confidence interval (see page 16 on this presentation)

    • the upper limit on bins with no entries can be interpreted differently. By default, a one-sided 68% confidence bound is used. The behavior can be changed using the uncertainty_type = asymmetrical_double_sided_zeros, which will use a two-sided 68% confidence bound.

    • this method doesn’t support weighted histograms. For more details, see the note about uncertainties when the histogram entries are weighted.

Simple error hist

The uncertainty on the efficiency (ratio of two histograms h1 and h2 when the entries of h1 are a subset of the entries of h2) in get_efficiency() is calculated following equation (19) of: