Note

You are not reading the most up to date version of Gammapy documentation.
Access the latest stable version v1.3 or the list of Gammapy releases.

excess

gammapy.stats.excess(n_on, n_off, alpha)

Estimate excess in the on region for an on-off observation.

$$\mu_{excess} = n_{on} - \alpha \times n_{off}$$

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

excessnumpy.ndarray

Excess estimate for the on region

Examples

>>>

>>> excess(n_on=10, n_off=20, alpha=0.1)
8.0
>>> excess(n_on=4, n_off=9, alpha=0.5)
-0.5