An alternative approach to the decision threshold

Two effects were identified that induce the dependence of the decision threshold on the uncertainty of the conversion factor. With the first effect, the conversion factor influences the decision threshold directly, through its variability. With the second effect, the variability of the conversion factor influences the decision threshold only when it is not evaluated for the null measurement. Then, the variability of the conversion factor influences the value of the measurand, where the decision threshold is evaluated. Both effects are explained and evaluated. •The concept of the decision threshold is challenged.•The decision threshold depends on the uncertainty of the conversion factor.•It must cover the 1-α part of the distribution of conversion factors.•If derived from a test measurement it is given at the null measurement uncertainty.