excess_error¶
-
gammapy.stats.excess_error(n_on, n_off, alpha)[source]¶ Estimate error on excess for an on-off measurement.
\[\Delta\mu_{excess} = \sqrt{n_{on} + \alpha ^ 2 \times n_{off}}\]TODO: Implement better error and limit estimates (Li & Ma, Rolke)!
- Parameters
- n_onarray_like
Observed number of counts in the on region
- n_offarray_like
Observed number of counts in the off region
- alphaarray_like
On / off region exposure ratio for background events
- Returns
- excess_error
numpy.ndarray Excess error estimate
- excess_error
Examples
>>> excess_error(n_on=10, n_off=20, alpha=0.1) 3.1937438845342623... >>> excess_error(n_on=4, n_off=9, alpha=0.5) 2.5