 formula_26 is assumed to be known and formula_25 is the parameter to be estimated by the experiment.The standard procedure for setting an upper limit on formula_25 given an experimental outcome formula_31 consists of excluding values of formula_25 for which formula_33, which guarantees at least formula_34 coverage.Consider, for example, a case where formula_35 and formula_36 events are observed, then one finds that formula_37 is excluded at 95% confidence level.