This part of ISO 11843 specifies statistical values for assessing the capability of detection in Poisson
distribution measurements and whether a specific signal is significant or not. It is applicable when variations in
both the background noise and the signal are describable by the Poisson distribution. Two types of
approximation, the Simple approximation and the Square Root approximation, are used to approximate the
Poisson distribution to the Normal distribution, and are used to determine the variance, the critical value of the
response variable, and the minimum detectable value. This part of ISO 11843 should be applied to a sufficient
number of counts of the response variable.