Assessment of the reliability of subjective measures

In order to satisfy the conditions of scientific measurement, the measurement and analysis of the subjective characteristics require the definition of a complex design made up of two elements, one theoretical and the other methodological. The theoretical aspect concerns the definition of the concept of ’subjective’ (i.e., the definition and identification of the characteristics that can be defined as ’subjective”), the definition of the way in which they can be observed and of the problems that their observation can produce, and iIdentification of the reference measurement theory that defines the theoretical characteristics that make measurement scientific; the reference theory allows to identify the models aimed at verifying: objectivity, which is the ability of a procedure to measure without alterations due to extraneous factors, to be free from effects due to the researcher; this concept extends from procedure and measurement to data analysis and interpretation of results; precision, which is measured by checking the consistency of the measurement model; accuracy, which is the ability of a procedure to measure what it intends to measure (content). A measurement procedure that meets these requirements not only acquires scientific relevance but can also be standardized.