relative_sensitivity

pyirf.sensitivity.relative_sensitivity(n_on, n_off, alpha, min_significance=5, min_signal_events=10, min_excess_over_background=0.05, significance_function=<function li_ma_significance>)[source]

Calculate the relative sensitivity defined as the flux relative to the reference source that is detectable with significance target_significance.

Given measured n_on and n_off, we estimate the number of gamma events n_signal as n_on - alpha * n_off.

The number of background events n_background` is estimated as ``n_off * alpha.

In the end, we find the relative sensitivity as the scaling factor for n_signal that yields a significance of target_significance.

The reference time should be incorporated by appropriately weighting the events before calculating n_on and n_off.

All input values with the exception of significance_function must be broadcastable to a single, common shape.

Parameters:

n_on: int or array-like: Number of signal-like events for the on observations
n_off: int or array-like: Number of signal-like events for the off observations
alpha: float or array-like: Scaling factor between on and off observations. 1 / number of off regions for wobble observations.
min_significance: float or array-like: Significance necessary for a detection
min_signal_events: int or array-like: Minimum number of signal events required. The relative flux will be scaled up from the one yielding min_significance if this condition is violated.
min_excess_over_background: float or array-like: Minimum number of signal events expressed as the proportion of the background. So the required number of signal events will be min_excess_over_background * alpha * n_off. The relative flux will be scaled up from the one yielding min_significance if this condition is violated.
significance_function: function: A function f(n_on, n_off, alpha) -> significance in sigma Used to calculate the significance, default is the Li&Ma likelihood ratio test formula. Li, T-P., and Y-Q. Ma. “Analysis methods for results in gamma-ray astronomy.” The Astrophysical Journal 272 (1983): 317-324. Formula (17)