poisson_llu¶
-
hep_spt.poisson_llu(m)[source]¶ Return the poisson uncertainty at one standard deviation of confidence level. The lower and upper uncertainties are defined by those two points with a variation of one in the value of the negative logarithm of the likelihood multiplied by two:
\[\sigma_\text{low} = n_\text{obs} - \lambda_\text{low}\]\[\alpha - 2\log P(n_\text{obs}|\lambda_\text{low}) = 1\]\[\sigma_\text{up} = \lambda_\text{up} - n_\text{obs}\]\[\alpha - 2\log P(n_\text{obs}|\lambda_\text{up}) = 1\]where \(\alpha = 2\log P(n_\text{obs}|n_\text{obs})\).
- Parameters
m (int or numpy.ndarray(int)) – measured value(s).
- Returns
Lower and upper frequentist uncertainties.
- Return type
See also