The Complete Guide to Personality Tests

Know Thyself

“Know thyself” is a commonly-accepted piece of wisdom.

It has been for thousands of years - it was supposedly one of the Delphic maxims, attributed to Apollo via the Oracle at Delphi.

Carl Jung said it a little differently: “The world will ask you who you are, and if you don’t know, the world will tell you.”

Accurate self-assessment is essential to succeeding in life. Knowing your strengths and weaknesses gives you vast leverage compared to those who are ignorant. The philosopher Zeno put it this way: “nothing is more hostile to a firm grasp on knowledge than self-deception.”

As author and investor Tim Ferriss remarked in Tools of Titans, “The superheroes you have in your mind (idols, icons, titans, billionaires, etc.) are nearly all walking flaws who’ve maximized 1 or 2 strengths.”

Billionaire hedge fund manager Ray Dalio said it this way in his book Principles:

“We all have things that we value that we want and we all have strengths and weaknesses that affect our paths for getting them. The most important quality that differentiates successful people from unsuccessful people is our capacity to learn and adapt to these things.”

But how does one go about figuring out their strengths?

What about the opposite approach: minimizing weaknesses?

This article describes my exploration of personality testing to help answer those questions.

My First Personality Test

The first “personality test” I took was an aptitude test in middle school designed to tell me which careers I fit best.  

Unsurprisingly, it was pretty much useless. It told me to pursue careers in the sciences (which were my favourite subjects), and then told me average pay for those careers (a poor metric to show middle-school kids).

More recently, however, during my application to Founder Institute Montreal, I had to complete what Founder Institute calls their DNA Test.  They use it to predict the probability that someone will be successful as an entrepreneur.  

You can read more about it here, but the characteristics the test evaluates are Fluid Intelligence, Openness, Conscientiousness and Agreeableness.  Supposedly, the ideal entrepreneur has high fluid intelligence, high openness and moderate agreeableness.

It gave me a little bit of feedback, but I wanted more.

Personality Tests Revisited

Tim Ferriss’s book Tribe of Mentors is a large, detailed survey of successful individuals from a wide variety of fields, in which he asks the same 11 questions.  

Drew Houston, the founder of DropBox, is one of the people who participated.  The headline quote for his section is “Over the last few years, I’ve found myself looking at all my important relationships through the Enneagram lens. . . . I wish I had discovered it much earlier.”

He goes on to say this about the Enneagram (a personality test we’ll explore later):

“I’ve found the Enneagram to be incredibly helpful. At first glance it’s a personality typing tool like Myers-Briggs. There are nine Enneagram “types” and every person has one dominant type. But I’ve found it to be much more useful and predictive of how people actually behave. At first I was skeptical, but after reading the description for my type I found it spookily accurate in pinpointing what makes me tick: what motivates me, what my natural strengths are, what my blind spots tend to be, and so on. It’s helped me tailor my role and leadership style to my strengths.”

I was intrigued.  Being objective about my own abilities has always been important to me, and accurate perception of those abilities is necessary to improve them.

Later in Tribe of Mentors, Kristen Ulmer, one of the best extreme skiers in the world, also mentioned The Wisdom of the Enneagram by Don Richard Riso and Russ Hudson as one of her two favourite books.

She says:

“I love this book so much, in fact, that I wouldn’t date or certainly hire anyone unless I knew what their Enneagram type was. It’s like being armed with their operating manual, which prevents any confusion or potential conflict down the road.”

At this point, I knew I had to investigate the Enneagram, and personality testing in general, in more detail.

The Personality Tests

The following describes some of the major personality tests in use today, though it is not comprehensive.  

You should be acquainted with two definitions we’ll discuss in evaluating these tests:

  • Reliability: how consistently a test measures what it attempts to measure. In other words, are the results repeatable?
  • Validity: the degree to which an instrument measures what it claims to measure.  For example, an intelligence test should measure intelligence, not memory.

We will discuss these measures as we go through each of the following personality tests.


The Myers-Briggs personality test, more formally known as the Myers-Briggs Type Indicator (MBTI) is perhaps the most well-known personality test.

It is based on the theory of psychological types describe by Carl Jung, and the MBTI itself was developed by Isabell Briggs Myers in the 1940s.

The test will classify you into one of 16 personality types based on 4 “preferences”.  These preferences are as follows:

  • Favorite world: Do you prefer to focus on the outer world or on your own inner world? This is called Extraversion (E) or Introversion (I).
  • Information: Do you prefer to focus on the basic information you take in or do you prefer to interpret and add meaning? This is called Sensing (S) or Intuition (N).
  • Decisions: When making decisions, do you prefer to first look at logic and consistency or first look at the people and special circumstances? This is called Thinking (T) or Feeling (F).
  • Structure: In dealing with the outside world, do you prefer to get things decided or do you prefer to stay open to new information and options? This is called Judging (J) or Perceiving (P).

You’ll end up with a 4-letter code that is one of the 16 personality types.

The original Myers-Briggs has been subject to much criticism.  There are a variety of reasons why. Many early studies of validity were funded by groups with conflicts of interest. Validity has been shown to be poor on the S-N (Sensing-Intuition) and T-F (Thinking-Feeling) scales. It’s also been shown to have poor predictive validity of employees’ job performance ratings.  

Reliability: The test-retest reliability of the MBTI is also low - as many as 50% of people test into a different type when tested 5 weeks later.  That said, usually the movement isn’t too large - many move to adjacent types.

The other main issue is the bi-modal nature of the test - you are one type or another - which leaves little room for nuance.  This partially explains some of the reliability issues as well.

The types all tend to be positive and relatively vague, which means that people could fit into a number of them.  

This is known as the Forer or Barnum effect: individuals give high accuracy ratings to descriptions that are supposedly tailored to them, but intentionally vague.  It contributes to the widespread acceptance of things like astrology/horoscopes.

In general, the original test is no longer used by the psychology community. There are some variants that have been mixed or adapted with other models which may be more insightful.

The Big Five Personality Traits (aka The Five-Factor Model or FFM)

In brief, the Big Five model is based on five broad dimensions commonly used to describe human personalities.  These have been determined by a statistical analysis of personality survey data (called factor analysis).

This model of personality variation is one of the most widely-studied - typically using the 44-item Big Five Inventory - and generally accepted as the best model available right now.

The five factors examined in this test are:

  • Openness to experience (inventive/curious vs. consistent/cautious).  Describes a person’s preference for novelty and variety.
  • Conscientiousness (efficient/organized vs. easy-going/careless). Tendency for organization, self-discipline and preference for planned vs. spontaneous behavior.
  • Extraversion (outgoing/energetic vs. solitary/reserved). Tendency to seek the company of others, talkativeness, etc.
  • Agreeableness (friendly/compassionate vs. challenging/detached). Tendency to be compassionate and cooperative, and a measure of how trusting and well-tempered someone is.
  • Neuroticism (sensitive/nervous vs. secure/confident). Tendency for psychological stress, or how easily someone experiences unpleasant emotions.  Sometimes referred to as “emotional stability”.

This personality test has more evidence supporting it, particularly some specific findings:

  • Numerous studies have linked high scores of neuroticism with increased risk of developing a common mental disorder (depressive disorders, anxiety disorders, PTSD, panic, phobias).
  • Neuroticism can change in response to positive and negative life experiences.
  • High conscientiousness may add as much as five years to one’s life, and is associated with lower obesity risk.
  • Conscientiousness and agreeableness have a positive relationship with all types of learning styles, while neuroticism has an inverse relationship.
  • In work research, results have been mixed, but in general, high neuroticism is a bad thing.
  • For romantic relationships, again, generally high neuroticism is bad.

In Michael Pollan’s book How to Change Your Mind, he cites recent research on psychedelics at Johns Hopkins (psilocybin in this case), which showed those who had a “complete mystical experience” showed long-term increases in the openness to experience category.

Criticisms of the model include:

  • The model is not theory-driven, merely a statistically-driven model of certain descriptors.
  • A variety of flaws in the basis of the model (lexical hypothesis).
  • Limited scope (ie. doesn’t explain all of human personality).

That said, in the context of aiming to find out more about ourselves, the test has shown some scientific validity, and can provide some guidance on where we may want to improve.

Sixteen Personality Factor Questionnaire (16PF)

The 16PF test was developed over several decades of empirical research by several researchers, and provides a measure of normal personality.  

It was developed through the statistical factor analysis technique, similar to the development of the Big Five.

At the primary level, the 16PF measures 16 primary traits, and a version of the Big Five secondary traits at the second level.

One of the main differences of the test is that rather than rating oneself on a scale, it tends to ask about daily situations, with a yes/no answer.

The 16 factors measured are:

  • Warmth: outgoing, attentive to others, kindly, easygoing, participating, likes people.
  • Reasoning: abstract-thinking, more intelligent, bright, higher general mental capacity, fast learner.
  • Emotional Stability: adaptive, mature, faces reality calmly.
  • Dominance: forceful, assertive, aggressive, competitive, stubborn, bossy.
  • Liveliness: animated, spontaneous, enthusiastic, happy go lucky, cheerful, expressive, impulsive.
  • Rule-Consciousness: dutiful, conscientious, conforming, moralistic, staid, rule bound.
  • Social Boldness: venturesome, thick skinned, uninhibited.
  • Sensitivity: aesthetic, sentimental, tender minded, intuitive, refined.
  • Vigilance: suspicious, skeptical, distrustful, oppositional.
  • Abstractedness: imaginative, absent minded, impractical, absorbed in ideas.
  • Privateness: discreet, non-disclosing, shrewd, polished, worldly, astute, diplomatic.
  • Apprehension: self doubting, worried, guilt prone, insecure, worrying, self blaming.
  • Openness to Change: experimental, liberal, analytical, critical, free thinking, flexibility.
  • Self-Reliance: solitary, resourceful, individualistic, self-sufficient.
  • Perfectionism: organized, compulsive, self-disciplined, socially precise, exacting will power, control, self-sentimental.
  • Tension: high energy, impatient, driven, frustrated, over wrought, time driven.

Reliability & Validity: Generally, the 16PF is accepted as having good reliability and validity in application to areas like counseling, career development and personality assessment.  It can be considered on a similar level as FFM, though more comprehensive in evaluating traits.

The Enneagram (or Enneagram of Personality)

The Enneagram is a model of the human psyche consisting of nine interconnected personality types.  The origins and history are disputed, but the basis is not a scientifically-derived theory (then again, neither is the Big Five).

There are nine main personality types in the Enneagram, and they connect to others around the Enneagram figure:

In theory, they link via “stress/disintegration” and “growth/integration” - ie. what happens when you’re stressed vs. when you grow.  

For example, if you’re a type 3, you would move towards 9 under stress, and 6 when you experience personal growth or feel secure.

You may also have a “wing”, which is a tendency to share some of the characteristics of the types adjacent to your primary type on the Enneagram.  If you’re a 3, you may have a two-wing or a four-wing.

The nine main types are described as follows:

  1. The Reformer - rational, idealistic type: principled, purposeful, self-controlled, perfectionistic.
  2. The Helper - caring, interpersonal type: demonstrative, generous, people-pleasing, possessive.
  3. The Achiever - success-oriented, pragmatic type: adaptive, excelling, driven, image-conscious.
  4. The Individualist - sensitive, withdrawn type: expressive, dramatic, self-absorbed, temperamental.
  5. The Investigator - intense, cerebral type: perceptive, innovative, secretive, isolated.
  6. The Loyalist - committed, security-oriented: engaging, responsible, anxious, suspicious.
  7. The Enthusiast - busy, fun-loving type: spontaneous, versatile, distractible, scattered.
  8. The Challenger - powerful, dominating type: self-confident, decisive, willful, confrontational.
  9. The Peacemaker - easygoing, self-effacing type: receptive, reassuring, agreeable, complacent.

The Enneagram has not enjoyed the popularity of other tests like the Big Five, perhaps because of the emphasis on personal development and spirituality, and the lack of scientific basis for the theory.

Reliability & Validity: The most widely-used version in testing is the Riso-Hudson Enneagram Type Indicator (RHETI).

Early comparisons of the RHETI against the NEO PI-R (a version of the Big Five test) showed the test to be sufficiently scientifically valid and reliable for experimental use, and that results were correlated between the RHETI and the NEO PI-R.

My Own Experience with Personality Tests

With the above factors in mind, here are the tests I took.

Myers-Briggs Tests

I chose to take this test by Truity.  I’ve verified it with a few other free tests as well.

As we mentioned above, Myers-Briggs isn’t really accepted on it’s own as scientifically valid (or at least the leading test).

That said, I haven’t experienced the reliability issues mentioned; I consistently test at the same or similar profiles.

The biggest issue I have with Myers-Briggs is the lack of actionable information typically provided with results.  I wouldn’t bother testing.

The Big Five Tests

As the most-studied and currently accepted model, there are lots of options here, all slightly different, but based on the same model attributed to Goldberg, Costa & McRae.

I’ve taken this free test, this free test, and paid for the upgraded report of this (also free) test.

Of the three, perhaps unsurprisingly, the paid report from the final test yielded the most actionable results, and more detail about each section of my personality.

The best test from the Big Five model is the one offered by 16 Personalities.

Their model isn’t actually clearly defined, but based on their description is a combination both Myers-Briggs and the Big Five.  

They’ve adopted the naming convention of Myers-Briggs, and indeed I test as the same ENTJ profile, though they add a fifth personality trait to make me an ENTJ-A.

The test offers the most accurate and comprehensive free results of any of the Myers-Briggs or Big Five tests I’ve tried, and certainly the most comprehensive results of any test I’ve taken at all when you pay $29 for the full ~250-page report.

The free results still give you insights into things like strengths and weaknesses, how to succeed in relationships and at work, with friends, and parenting advice.

I found it to be accurate in describing what I know (or believe) about my own personality, and while you must always be cognizant of the Barnum effect, I believe this to be a valuable resource.

Ultimately, I think this is one of the best tests available, and recommend it.

16PF Tests

There are limited resources for the 16PF test, though you can take a free test here.

This test seemed relatively accurate in assessing my current traits; the downside is it offers little in telling me how to apply those effectively, or what my strengths and weaknesses may be.  

Enneagram Tests

I would recommend this Enneagram test as a free option, and would do the test including the instinctual variant (although of course you can do both).  It agreed with the more detailed paid test I did.

You can use the information on the Enneagram Institute’s website to interpret your results.  Information ranges from details about your personality to how you interact with other types, and information on how to grow personally.

This combination (free test + Enneagram Institute website info) provides some of the best actionable information I’ve found.  

I recognize that the Enneagram has not been rigorously studied scientifically, but I found the descriptions to be accurate.

The most valuable aspect of the Enneagram is the actionable information for someone to progress/regress through different behaviors.

I would also recommend taking the paid test offered by the Enneagram Institute.  It’s $12, and you’ll get a more detailed report tailored to you.

This also serves to confirm the findings of the free test, if you’ve taken that as well.

Calibrating Your Own Perception

Personality testing gives you a chance to improve your understanding of yourself, and identify your strengths and weaknesses.

It also gives you a chance to improve your perception of reality.  Here’s how:

Once you’ve completed the tests above, particularly the Enneagram tests, send the description of your type to close friends and family you can trust to be honest.

Ask them:

  • What characteristics of this profile seem most accurate for me?
  • What characteristics of this profile seem least accurate for me?
  • Which level of development would you say best describes me?

Ask yourself these questions too, and write down your answers before you get any responses.

When they give you their answers, check them against your own.  How close were you?  Are there things that surprised you? What blind spots or inaccuracies in your own perception can you infer from their responses?

Taking their input will help you calibrate your own perception of yourself, and identify areas where your perception is inaccurate.

A Word of Warning

The world of personality tests will no doubt continue to evolve.  It’s difficult to evaluate personality tests; making predictions is hard when there are still so many unknown factors affecting behavior.

Reliability and validity of most tests continues to be questioned, and needs more study.

With this in mind, you should make sure to remember:

  • These test results don’t define you, or your relationships, or anything else.
  • You can change outcomes, and you can change your own attributes if you like.
  • There will always be exceptions.

Getting Value from Personality Testing

That said, I still believe there is value in completing tests, and I believe the following are the most valuable:

Try and pay attention to the following:

  • What are my strengths and weaknesses?
  • Which of these really resonate with who I believe I am?
  • Which are surprising?
  • What actionable items can I work on to improve myself?
  • Which of my strengths can I maximize to my benefit?

Remember Tim Ferriss’s quote:

“The superheroes you have in your mind (idols, icons, titans, billionaires, etc.) are nearly all walking flaws who’ve maximized 1 or 2 strengths.”

I would recommend you have your current (or prospective) spouse or significant other also fill them out.

Once you have these results, you can use the information on the Enneagram Institute’s website to better understand their profile, and how you relate.

I view it like this: you shouldn’t believe everything these tests tell you, especially if you strongly disagree with them.  But you should use all the information and insights you can to better understand yourself, your partners, your colleagues, and your close relationships.  

There is little downside.

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