Psychometric

Psychometric refers to the field and methods of measuring psychological constructs — personality, intelligence, attitudes, abilities. A "psychometric instrument" is a test or scale designed and validated for that purpose.

The defining property of a psychometric instrument (as opposed to a casual quiz) is that its psychometric properties have been studied and documented: - Reliability: do you get a similar score if you take it twice (test-retest)? Are the items internally consistent (Cronbach's alpha)? - Validity: does it actually measure what it claims to (convergent validity with other measures of the same trait, divergent validity from unrelated traits)? - Norms: how does an individual's score compare to a representative population sample?

The IPIP-NEO-120, the personality instrument Are We Friends? uses, has all three. The MBTI famously has poor test-retest reliability (~50% of people get a different type when they re-take the test) — which is one of the main reasons academic psychology has moved to the Big Five.

When someone calls a personality test "research-backed," the question is whether the instrument has published psychometric properties — not whether the underlying theory has any research papers about it.