Over the last couple of years I have increasingly studied and used personality tests for personal and professional uses, both for myself and for others. I’ve seen a variety of benefits, but these assessments are not without drawbacks, and not all assessments are created equal.

Personality assessments, at their finest, are statistical tools created and validated by teams of psychologists and mathematicians. At their worst, they are snake oil, invented and promoted by people with no real expertise, and claimed to achieve results that stretch credibility, sometimes even though they’ve been repeatedly shown not to work. There are many shades of gray in between: tests that work okay but are difficult to interpret, tests that show results that aren’t really actionable.

What Are Assessments Good For?

I have found that the better-designed assessments can be helpful for understanding a variety of aspects of myself and others. I always use myself as the first test subject. Part of my personality (which the best tests confirm!) is a desire to improve myself through observation and understanding, so I can see my strengths and weaknesses.

I use the insights to help me understand how I can do things such as:

  • Understand where and when I’m likely to behave well or badly.
  • Predict how a person will respond to interactions and adjust my approach.
  • Communicate effectively, using a person’s natural style instead of my own.
  • Match a person’s strengths to a situation.
  • Ask better questions.

I also use assessments, individually and with teams, to:

  • Help people understand themselves and their desired career paths.
  • Perform pairwise comparisons between people and help coach them through the results.
  • Help groups understand how they’re similar or different (e.g. sales vs marketing vs engineering) and how to accommodate those differences.
  • Determine what behaviors, motivations, and skills are required for a role, and in which areas a candidate is a good match for that (job and gap reports).

What Kinds Of Assessments Are There?

Broadly speaking, many assessments try to examine a person from a few viewpoints:

  • Behaviors. These are externally observable tendencies. Generally they focus on a person’s preferred style of behavior, sometimes under a variety of situations such as stress. Behaviors often include the style of interaction with others as well as alone.
  • Motivators. These “values” or “driving forces” are internal preferences or situational factors that can help explain why a person behaves as they do.
  • Competencies. Tests of competency try to evaluate how well a person achieves specific types of tasks. Some tests try to evaluate “raw intelligence,” while others evaluate specific skills.
  • Worldview. These assessments rate a person’s attitudes and opinions.
  • Differences. Some assessments don’t try to judge what a person is good/bad or high/low at, but where they’re unusually different from other people; in other words, what makes them most uniquely themselves.

I have found the behaviors and motivators far easier to understand than many of the other types of assessment results. I work with a professional management coach and I’m still studying and trying to learn to interpret some of the worldview assessments, for example.

Are Assessments Valid And Useful?

There’s a lot of controversy over these assessments and their use in hiring or other professional situations. You can do a quick web search and immediately find more information than you need about the usefulness and validity of the assessments. For example, a CIO article concludes that personality assessments need to be used carefully but can be valuable, and The Guardian reports that psychology studies across the board don’t stand up well to rigorous science.

After using them for a while, I’ve come to the opinion that there really are good assessments, but the bad assessments give all of them a bad reputation.

But even the best assessments are imperfect. They’re based on statistically likely observations about large populations of people, and in my experience are often pretty accurate predictors, but not always. I’ve known a couple of people for whom specific results were quite wrong. Part of this comes down to how the person takes the assessment, and some kinds of personalities are actually harder to analyze than others. In other words, some people are naturally going to give answers that result in highly accurate outcomes, and some people will micro-analyze and defeat the test while they take it.


It’s important to be careful when using the assessments in hiring, in particular. If you base a hiring decision on an assessment that hasn’t been subjected to adverse impact analysis, you could open yourself to claims of discrimination. I use the results to help me have a better conversation with the candidate, not to make a hire/reject decision.

A lot of the tests are just fluff. They’re like horoscopes, designed to sound meaningful for everyone. In fact, there have even been experiments on how much people believe personality assessments. (People believe the tests are accurate, even when the results are copy-pasted from an astrology book and everyone got the same answers. This is known as the Barnum effect. You can take this bogus assessment yourself; after doing so, see how good you think the results are. This is a good trick to play on your friends.)

Ironically, you can usually tell the smoke-and-mirrors tests by looking at how polished and slick the reports are. The better tests are usually more concerned with information than appearances.

In particular, my personal belief is that the Myers-Briggs Type Indicator, which is the most popular and well-known by far, is not very revealing. After you’ve studied other assessments for a while, the MBTI looks weak in comparison. I’ll let you study this on your own if you’re interested. For a little light reading you might be interested in how the MBTI types match up to patron saints.

The better-quality assessments are based on well-known models of human psychology that were invented/discovered by researchers and have subsequently been commercialized, often by many companies. The Big Five and the DISC model are examples. There are many implementations of these models.

When researching personality assessments online, I would caution you to take what you find with lots of skepticism. Predicting whether a person is a good fit for a job is an extremely interesting outcome for companies, because hiring the best people and avoiding bad hires is often the difference between success and failure as a business. As a result, the companies that develop and administer the tests are making extremely good profits, and sometimes go to extremes to ensure that the information available online makes them look good.

Even Wikipedia is not immune to this effect. Many articles about the assessments are full of weasel words and blatant advertising, and few people in the general public have the knowledge or motivation to properly moderate the articles, so you end up with claims like this:

The [redacted] has been considered the “gold standard” in personality testing[citation needed]

In general, my personal view is that any test that is offered exclusively by a single company is suspect. I give more credence to models that were developed by researchers and then implemented by companies. I am also skeptical of companies that make sweeping claims such as The XYZ assessments are ideal for a wide range of applications… In my opinion, no assessment is “ideal” for anything, much less a “wide range” of things. Unfortunately, even the tests that I believe are good use verbiage like this.

A word of caution: just because the questions you have to answer during the assessment seem vague or contradictory doesn’t mean it is fluff. Many of the personality tests are designed to force you to compare and rank things that aren’t directly comparable. By doing this in a variety of dimensions, they are able to use factor analysis to get multi-dimensional results. This is a legitimate statistical technique.

Available Assessments

There’s a stunning range of assessments available, ranging from amateur to academic to professional. For personal interest, they might all be fun to use, but for professional purposes I’d stick with ones that have invested in large-scale, longitudinal studies of effectiveness and adverse impact.

Assessments and companies that are widely used in business, from what I observed through discussions with various managers and recruiting specialists, are:

Most of the companies mentioned provide a range of assessments such as DISC and Big Five. Many of them also provide a free assessment, so if you’re interested in taking one for yourself, you don’t have to pay a lot of money for it.

Here are some other resources online, each offering one or multiple tests:

But wait, there’s more. Here are some other tests I’ve seen but haven’t examined much:

  • The FIRO-B. I didn’t take a much deeper look because after examining one person’s report I concluded it wasn’t very useful. It’s also administered and sold by CPP, the company that promotes MBTI. I distrust it.
  • The Interpersonal Style Inventory.

The DISC Model

One of the most widely commercialized personality models is the DISC model. It’s one of the ones I use, and I think it’s probably one of the best to get started with.

DISC is an acronym for four dimensions of a person’s behavioral style—things that are externally observable. Each dimension can rank from very low to very high. There’s a fair amount of interplay amongst the dimensions, and various combinations of them tend to indicate different things. In my own words, here’s a gross oversimplification:

  • The D stands for Dominance, sometimes called Directness. It relates to how you respond to challenges in your external environment: do you attack them forcefully and aggressively (high-D) or do you avoid or try to solve them indirectly? A person who’s high D gets right to the point and pushes themselves and others, and also in my experience tends to become very Defensive when challenged or coached.
  • The I stands for Influence, or Interactivity, and relates to how much you try to persuade others. A high-I person can win people to their point of view, typically by promoting its benefits. They are also similarly attracted to nice things themselves, and can sometimes be distracted by “shiny objects” or aesthetically pleasing things or experiences. A high-I person also tends to need lots of social interaction and may like being praised, especially in public.
  • The S stands for Steadiness or Stability, and relates to preferred working style. A high-S person is patient and a focused single-tasker; a low-S person is a plate-spinning multi-tasker who’s easily distracted and likes instant gratification. High-S people also get stressed when placed in multi-tasking situations.
  • The C stands for Compliance or Caution. High-C people care a lot about the world’s rules, standards, and procedures, and they want to make sure they’re following the rules because they believe that provides safety. Low-C people think rules are for controlling other people.

Many people are high in two dimensions and low in the other two. It’s a little less common, but people can be moderately high in a few, and I’ve even seen a few people who were high in three categories. Programmers, for example, tend to be high-S, high-C. Many salespeople are high-I and either high-D or high-S.

You can find many places to take the DISC test, such as TTI Success Insights’s website, Tony Robbins’s website, and some of the free testing sites I linked above. I have taken lots of those tests and gotten almost exactly the same results from all of them, no matter which provider I used.

I have also asked about 20 of my friends to take some of these tests and share the results with me so I could practice studying and understanding people’s personalities. I feel this has helped me be more observant and a better judge of character.

The TTI Success Insights and Tony Robbins’s test website both provide free DISC and Values tests. The benefit of adding the Values test is that the assessment tries to help you understand potential strengths and conflicts between the ways you like to behave, and the things that motivate you.

The Big Five tests are similar to DISC in some ways, but I don’t find it as easy to apply or understand. I wouldn’t say it is inaccurate, but it feels incomplete to me, as though some of the things it measures are secondary rather than primary, and there are some primary things missing (e.g. how aggressive someone is). This may be a function of how familiar I am with DISC, rather than an objective judgment of the models. To be fair, DISC doesn’t seem fully faithful in my experience either.

Motivators Models

Values are the things a person cares about—what motivates them. Unlike behaviors, which seem to be pretty steady for a lot of people over the long term, values are sometimes situationally driven and can change, especially with major life events such as getting married, having children, moving, or changing jobs.

TTI’s motivators are theoretical, utilitarian, aesthetic, social, individualistic, and traditional. The InnerMetrix motivators (values) are aesthetic, economic, individualistic, political, altruistic, regulatory, and theoretical. Although they use similar names, I think the meanings are a bit different in some nuances. I don’t prefer one of these to the other, but I’m more familiar with the TTI assessments because I’ve used them a lot more.

Update: TTI’s new Driving Forces assessment is based off the motivators assessment but is more nuanced and some of the items are renamed to reflect that.

Here’s an example, using the TTI Driving Forces assessment. One of the dimensions, Utilitarianism, varies between Selflessness and Resourcefulness. Selfless - People who are driven by completing tasks for the greater good, with little expectation of personal return. Resourceful - People who are driven by practical results, maximizing both efficiency and returns for their investments of time, talent, energy and resources. In other words, resourceful people do things intentionally.

Another dimension is what motivates how you behave towards others. Now called Others, previously called Social, it ranges from Altruistic (People who are driven to assist others for the satisfaction of being helpful or supportive) to Intentional (People who are driven to assist others for a specific purpose, not just for the sake of being helpful or supportive).

Both of these dimensions relate to the expected outcome of a decision or activity: do you do it for the greater good, or to achieve a goal? I’ve found this to be extremely revealing about people. It’s not to say one is good or bad; all of these dimensions are good for different things. Picture an EMT versus a hospice care nurse, or the way a real estate developer feels about a plot of land versus how a biologist or forest service worker does. You can probably predict which types of people are best suited for those jobs.

Matching people to jobs they’re naturally motivated to do results in effortless, joyful work that doesn’t feel like work and never gets stale.

Update: After a few years using the TTI values assessment, now called Driving Forces, I have grown more and more impressed with it. Watching people react to their assessments hundreds of times, along with observing them in interview settings of 60-90 minutes or even longer, I have come to see it as extremely accurate.

Strengths Assessments

It’s an open topic of debate whether one should try to work with their strengths and ignore their weaknesses, or try to improve their weak points. Some, such as Drucker in his classic Managing Oneself, argue that you should find your strengths and use them, because your weaknesses are often hard to improve. I believe that being aware of my weaknesses has helped me to improve some of the “low hanging fruit” over time, and some weak points are pretty easy to improve dramatically.

Two projects that try to help people understand their strengths and weaknesses, and particularly their most unique strengths and weaknesses, are the StrengthsFinder 2.0 and StandOut assessments.

Both of these have companion books. If you buy the book, you get a code that lets you take the assessment.

Someone recommended the StrengthsFinder book to me. To tell the truth I found it difficult to understand the results. There are way too many dimensions to the report and I don’t think all of them are clearly distinguished from each other, and the names and descriptions of them seem to be extremely general as well. Besides, they don’t seem to mean what they say; it’s as though the terms are redefined instead of using the accepted meanings of the words.

I did find the StandOut report to be more straightforward, but I don’t think I have found it interesting or highly useful on an ongoing basis. I seem to continue to return to the DISC and Values results for further study.

I also feel that the DISC and Values results are more well-developed and have benefited from being applied to many more people. For example, they’ve been used widely enough that they’re evaluated in context of a culture (the report takes into account whether you’re a Spanish-speaking American, for example). I think that provides a greater specificity.

I do not use these assessments in hiring. I use TTI’s more advanced reports (competencies and worldviews), which are only available in the paid reports. But for low-cost reports I think StandOut is a reasonable one you can use on a personal basis.

The Bhagavad-Gita

And now for something completely different!

Personality profiling and categorization isn’t new. The Bhagavad-Gita’s last third contains extensive discussion of the different types of people. It separates them into three major categories, each influenced by a guna (strand or quality).

I don’t take this seriously, and I don’t think the last third of this great text is the most worthy of deep study. But it’s still fun and interesting in some ways to think about how the author of the Gita categorizes people, their modes of worship, their types of action, the kinds of foods they eat, and so on:

When the light of knowledge shines forth
through all the gates of the body,
then it is apparent
that sattva is the ruling trait.

Greed and constant activity,
excessive projects, cravings,
restlessness: these arise
when rajas is the ruling trait.

Darkness, dullness, stagnation,
indolence, confusion, torpor,
inertia: these appear
when tamas is the ruling trait.

This excerpt is from Stephen Mitchell’s wonderful new translation of the Bhagavad-Gita.


I’m convinced that the better-quality personality assessments are meaningful and useful, though not perfect. In my opinion they’re good tools for personal and professional development of oneself and others, as well as improving interviews.

I use the TTI assessments professionally. I know people who use Caliper, Chally, and Criterion among others.

For personal use I wouldn’t be afraid to suggest getting the free assessments from any of these, as well as the InnerMetrix ones from Tony Robbins’s website (which may also be available for free elsewhere too, but I haven’t looked).

For professional use I would suggest working with an experienced management coach. These companies often have networks of certified professionals who are trained in administering and interpreting their assessments, as well as using them in an ongoing process of improvement. My coach is Brad Eure.

I wrote in quite a bit of detail about the use of personality assessments in VividCortex’s ebook on building and managing a team of database administrators. That ebook contains actual data from volunteers who took the assessments. It may be interesting further reading.

Addendum: After a lot of further experience with personality tests in the teams I manage, as well as taking many more tests myself, I am fully convinced that the TTI Success Insights evaluations, especially the full battery of four models, is the best on the market. These assessments use models that match human behavior, values, etc very well. They are also extremely accurate. They resist “gaming” and other types of manipulation. The more I use them the more impressed I am. See this blog post for more on some of the additional assessments beyond DISC and Values/Driving Forces.

Stock photos by Susanne Nilsson and William Iven.

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