2. Cumulation model

As with all measurements, the first thing to do is to define the object to be measured (measurand). The definition of the measurand is particularly important in the case of aggregations, as it removes any potential controversy over the legitimacy of aggregating measurements obtained from quantities that may be radically different.

Some examples of accumulations are given below:

• annual sum of chemical contaminant discharges in a plant's effluent: the total is calculated from multiple samples taken throughout the year;

• total tritium activity in liquid effluent, calculated by summing free tritium and organically bound tritium. In this case, the sample is identical, but the analytes (free tritium and organically bound tritium) are different;

• concentration...