Trajković, G. (2008). Measurement: Accuracy and Precision, Reliability and Validity . In: Kirch, W. (eds) Encyclopedia of Public Health. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-5614-7_2081 Definition Measurement is the process in which numbers or other symbols are assigned to the characteristics of the units that are observed, in such a way that the relation between numbers or symbols reflects the relation between characteristics that are the subject of the research.