What is the linearity of a measurement method?
Determine a model that fits observed data as closely as possible

According to EEC Explanatory Note III/844/87, the linearity of a measurement method is its ability, within a certain interval (measurement range), to obtain measurement results directly proportional to the amount (e.g. concentration) of substance in the sample analyzed.

In practice, this means that if we introduce a theoretical data item x on several levels, the measurement process will give us a proportional response y for each of the levels. This is the case of a calibration range, for example.

Following a calibration, we have three pieces of information:

• a variable x: value s introduced s known s (standard) ;

• a variable y: response s obtained by the s measurement method from x ;

• a relationship between these variables, known...