ABSTRACT
Many subjective concepts such as client satisfaction, problems with alcohol, or personality traits can be measured using lists of items that are aggregated secondarily into a global composite score. These lists of items are often called “scales.” They are particularly interesting when complex constructs are to be measured. In this context, if an interviewee is asked a single question, the answer can be dubious. Conversely, if several items each tackle a simple, unambiguous aspect of the construct, then the summation of all the answers can provide a trustworthy measurement.
