Are personality tests accurate?
Some are, for some purposes. "Accurate" breaks down into two questions: are the results consistent (reliability), and do they mean what the test says they mean (validity)?
Reliability: are results consistent?
- Test-retest reliability: do people get similar results when they take the test again some weeks later?
- Internal consistency: do the items meant to measure the same thing agree with each other?
- Reliability is necessary but not enough: a test can be consistently wrong.
Validity: do results mean what they claim?
The Standards for Educational and Psychological Testing (AERA, APA and NCME, 2014) treat validity as evidence for a specific use, drawn from five sources:
- Test content
- Response processes: how people actually answer
- Internal structure: whether scores group as the model says
- Relations to other variables, such as established measures
- Consequences of using the test
A test can be well supported for one use, such as self-reflection, and unsupported for another, such as selection.
Two ways results mislead
- The Barnum effect: people rate vague, general descriptions as highly accurate for them personally. See the Barnum effect.
- Faking: when stakes are high, people answer to look good. Forced-choice formats reduce this but do not remove it (Cao and Drasgow, 2019).
What the evidence says about well-known tests
Trait measures such as the Big Five have the broadest research base. For the MBTI, a 1989 study found its scales relate to four of the five factors (McCrae and Costa, 1989), and later work found little support for the sharp type boundaries a type model implies (Bess and Harvey, 2002). Popularity and accuracy are different things.
Where the ICA stands
The ICA is a self-report behavioral-preference assessment, and its accuracy is currently being studied. It is not a clinical, medical or diagnostic test, does not measure intelligence or cognitive ability, and does not screen for any condition. Its design facts can be checked today; its structure, stability and relationships to established measures are under study. The claims ledger lists each claim by status, and the protocol says how it will be tested.
How to check any test yourself
- Find the technical manual or published evidence. If there is none, treat results as unverified.
- Check that the evidence matches your use.
- Take it twice, a few weeks apart, and compare.
- Read a description written for a different result. If it fits you just as well, be cautious.
Questions
Which personality test is most accurate?
There is no single answer: accuracy depends on the use. Trait measures based on the Big Five have the most research behind them.
Is the ICA accurate?
Its accuracy is currently being studied. See the claims ledger.
Sources
Keep reading
Take the next step.
How any personality test's accuracy is judged: reliability, the five sources of validity evidence, faking, the Barnum effect, and where the ICA stands.