@TomJewell

3) _It's about #TestScores_

Not always discussed explicitly in relation to all quality indicators and most frequently in the relation to "#validity", the process of validation produces evidence for the validity of #TestScores (as opposed to the validity of the test!).

The "Standards" make that very clear for the term "Validity" [2014, p. 11]:
"...the degree to which evidence and theory support the interpretations of test scores for proposed uses of tests"

#Psychometrics