Are personality tests accurate? Types, traits and what a second try shows

At a team day you get a color, from a career coach four letters, and on the internet a row of five bars. All three are called a personality test, and each rests on a different model. This article compares them on four points: what they measure, what a second try shows, whether the questions are public, and what a result cannot say. At the end we say what our own test is and what it is not.

What each kind of test measures

DISC sorts behavior into four styles. Wiley, which publishes the Everything DiSC version, calls it "a personal development learning experience that measures an individual's preferences and tendencies based on the DiSC model" and places the styles on two axes, from active to thoughtful and from questioning to accepting. The result is a style, sometimes with a second one beside it. It gives a team one shared vocabulary, and it is coarse by design.

The Myers-Briggs Type Indicator asks you to pick a side in four pairs, such as extraversion or introversion. The publisher writes that "there are 16 possible combinations of letters leading to 16 distinct MBTI personality types", and adds a line that deserves a second read: "The MBTI assessment sorts for preferences; it does not measure traits, ability, skill, or character." A type says which way you lean, by the publisher's own account, and nothing about how good you are at anything.

The Big Five has no single author. It came out of decades of research into the words people use to describe each other, and the same five bundles kept turning up. In 1987 McCrae and Costa found the five in 738 peer ratings of 275 adults as well as in the self-reports of the same people, and argued for adopting the model in personality research. A Big Five result is a position on each of five scales, with no box around it:

• Extraversion: how much energy you get from being around other people and from a busy setting.
• Agreeableness: how much you focus on the feelings and interests of other people.
• Conscientiousness: how much you care about order, planning and finishing things.
• Emotional stability: how strongly tension and moods affect you.
• Openness: how much you are drawn to ideas, imagination and new thoughts.

No name comes out and no color, and that is what makes the result usable a second time.

What a second try shows

Taking the same test twice is the plainest check. For the type indicator the publisher addresses the best-known figure on its own facts page: across a five-week retest period, 50 percent of participants received a different classification on one or more of the scales. The company points out that the number comes from a 1979 study on an older form, and reports for the current version correlations of 0.81 to 0.86 between the first and second score in a sample of 1,721 adults retested after six to fifteen weeks. Its Form M manual supplement gives .57 to .81 across intervals from under three weeks to over a year, in a sample of 409.

Those are correlations of the underlying scores. The catch sits in the step after the score. A type needs all four letters to stay on the same side of the line, and someone who answered 52 to 48 on one pair can answer 48 to 52 after a bad night. Pittenger made that point in the Consulting Psychology Journal in 2005. The scores behind the letters are continuous, and cutting them in two turns a small shift into a different type. On a scale the same person moves a few points and stays where they were, in the middle.

For the Big Five there is a longer view. Costa and McCrae followed 983 adults for six years on the NEO Personality Inventory and found retest stability quite high for all five dimensions, for men and women alike, and concluded that their data support the position that personality is stable after age thirty. That is the record for one instrument, and it says nothing about a free test on a website that shares only the five names.

Who owns the questions

The type indicator is a registered trademark, taken through practitioners certified by the publisher; DiSC with a small i is a Wiley brand with its own questionnaire. The International Personality Item Pool, hosted by the Oregon Research Institute, holds 3,320 items and more than 250 scales, and states that they "are in the public domain, which means that one can copy, edit, translate, or use them for any purpose without asking permission and without paying a fee". The site went live in 1998 on a grant to Lewis Goldberg, who wrote most of the items. The fifty-item Big-Five Factor Markers, ten per factor, go back to his 1992 paper in Psychological Assessment, and the site lists an alpha between .79 and .87 for each ten-item scale.

For a reader that means you can read every question before you answer one, and set a result from one site beside one from another site that uses the same items.

What no result can say

A questionnaire records what you say about yourself in a few minutes. It does not watch you in a meeting, and it cannot tell whether you answered as you are or as you would like to be. That holds for all three models. There is no good score on agreeableness and no wrong letter. A type does not measure ability, as its publisher says, and a trait score does not say how you perform in a job; the studies above measure consistency, and nothing about what someone did afterwards. A percentile needs a group of people who took the same test, and a site that shows one without saying how large that group is has skipped a step.

What the Skillido Personality Check is, and what it is not

Our free Personality Check is 40 forced choices. Each time you see two statements from the fifty IPIP markers and pick the one that fits you better; every dimension appears in 16 pairs, so all five weigh the same. Because each choice gives one dimension a point and withholds it from another, your score is a share of your own choices. The average over the five is always 50, and a high score means you picked that dimension more often than your other four. It says nothing about other people. You see the five scores, each high, middle or low, right away and without an account; no type comes out. Once 50 people have completed the check, a percentile appears per dimension, set against the other players on this site. How the pairs were put together is on the Big Five test page.

The Personality report for €9.95 adds the statements you chose per dimension, how each level often shows at work, in teamwork and in communication, and a comparison with your own earlier checks. One payment, no subscription. We sell it in Ireland, Malta and the Netherlands for now.

Frequently asked questions

Which is more accurate, five traits or sixteen types?

Accurate is the wrong measure, because they report different things. A type is a label for which way you lean; a trait profile is five positions on five scales. For a result you can compare with a later one, scales do that; a type only holds when all four letters stay on the same side.

Why did I get a different type the second time?

Each pair has two outcomes, and many people sit close to the middle of at least one pair. A few answers the other way and the letter flips. A scale score shows that you are in the middle instead of placing you on one side.

Is the free sixteen-type test online the real instrument?

Usually not. The well-known free tests use the same four letter pairs and the same sixteen names, but they are separate questionnaires from other companies; the instrument itself is taken through certified practitioners.

Does the Skillido Personality Check give me a type?

No. You get a score and a level on each of the five dimensions, and from 50 players onwards a percentile per dimension against the other players on this site.

Sources

• The Myers-Briggs Company, MBTI facts and common criticisms, on the 50 percent figure, its 1979 origin and the 0.81 to 0.86 retest correlations: themyersbriggs.com
• The Myers & Briggs Foundation, reliability and validity of the instrument, on the sample of 1,721 adults retested after six to fifteen weeks: myersbriggs.org
• The Myers & Briggs Foundation, Myers-Briggs overview, for the two quoted sentences on the sixteen types and on sorting for preferences: myersbriggs.org
• Schaubhut, Herk and Thompson, MBTI Form M Manual Supplement, table 5, retest correlations of .57 to .81 in a sample of 409: themyersbriggs.com (PDF)
• Pittenger, D. J. (2005), Cautionary comments regarding the Myers-Briggs Type Indicator, Consulting Psychology Journal: Practice and Research, 57(3), 210 to 221: doi.org
• McCrae, R. R. and Costa, P. T. (1987), Validation of the five-factor model of personality across instruments and observers, Journal of Personality and Social Psychology, 52(1), 81 to 90: pubmed.ncbi.nlm.nih.gov
• Costa, P. T. and McCrae, R. R. (1988), Personality in adulthood: a six-year longitudinal study of self-reports and spouse ratings on the NEO Personality Inventory, Journal of Personality and Social Psychology, 54(5), 853 to 863: pubmed.ncbi.nlm.nih.gov
• International Personality Item Pool (Oregon Research Institute), the public domain statement, the item count and the 1998 launch: ipip.ori.org, and the fifty-item Big-Five Factor Markers with their alphas: ipip.ori.org/newBigFive5broadKey.htm
• Goldberg, L. R. (1992), The development of markers for the Big-Five factor structure, Psychological Assessment, 4(1), 26 to 42: doi.org
• Wiley, What is the Everything DiSC model, for the quoted description and the two axes: everythingdisc.com
• How our own pairs are built and the percentile rule: the Big Five test page

The quotations are taken word for word from the pages as they were online on 7 October 2026. DISC, DiSC, MBTI and Myers-Briggs are trademarks of their owners; Skillido is not connected to them.

Who wrote this

This article was written by the Skillido editorial team. Skillido is a product of Next Day Online B.V. in Wilp, the Netherlands, registered with the Dutch Chamber of Commerce under number 08198136. We make a free test ourselves and sell a report on it, and you may want to weigh that as you read.

If something here is wrong, write to hallo@skillido.com and a person will correct the text.