The so-called 5 Ms method is recommended to identify and assess the various factors influencing the measurement uncertainty. It is based on an Ishikawa diagram (see figure). The influencing factors are divided into 5 groups: manpower, method, material, medium and machinery. In each group, additional scales show the causes and potential sub-causes (see example).

It is important to know the different sources of uncertainty: on the one hand, it helps to reduce uncertainties and improve the quality of the measurement result, and on the other hand it highlights the important points to control to ensure a quality result.

Example of application of the 5 Ms method: measurement of metals (Pb, Cd, As, Ni) in atmospheric dust particles.

Source: Laboratoire Central de Surveillance de la Qualité de l’Air (2010)