Introversion, Extroversion and the Percentage of Personality Type

personality type

I am an INTP — introvert, intuitive, thinking, perceiving. If this is all Greek to you, let me be the first to introduce you to the Meyers-Briggs Personality Type. According to the Myers-Briggs Type Indicator (MBTI), this combination of letters means I am conceptual, analytical, intellectually curious, adaptable, independent and critical. I love ideas and pursue understanding.

Sounds exactly like me. Exactly.

I learned my Meyers Briggs personality type by taking a rather involved multiple-choice evaluation. But there are shorter tests online that work reasonably well. If you don’t know your type, check it out here. (I’ll wait.)

It’s pretty trendy to know what your personality type is and to identify the characteristics that you share with others. Being an INTP — remember, I love ideas and pursue understanding — I think this is a really good thing. (Also being an INTP, I think it’s a good idea for folks to get the real Meyers-Briggs test, if they plan to use the results in any serious capacity, like workplace team building or couples therapy.) You don’t have to agree with the veracity of these personality types to find them interesting and entertaining. Personally, I’ve found that knowing my type helps me make decisions — like striking out on my own as a freelance writer.

But what I find in the many, many articles on this subject is how unique the results seem. So many of my friends have said, “Wow! No wonder I feel so [misunderstood/alone/different]! Only 5 percent of the population has the same personality type as I do!”

On some level, and with some things, we all want to feel singular. Seems to me, personality types are one of those things.

But these small percentages have always bugged me a little bit. And that’s because of the math.

There are four preferences in the Meyers-Briggs personality type: introversion vs. extroversion, sensing vs. intuitive, thinking vs. feeling, and judging vs. perceiving. (I won’t get into the details of these characteristics, but do know this: judging isn’t a bad thing at all. Learn more at The Meyers Briggs Foundation website.) Since there are two options per preference, there are 16 possible personality types according to the Meyers-Briggs test.

I think we forget that there are so many different combinations. And that clouds our understanding of what is rare and what is not rare.

In fact, the Meyers Briggs Foundation has studied the occurrence of each of the 16 personality types in the population.

First, a disclaimer: already, this is not a random sample. The foundation used data that is reported to them, which means that only people who have taken the MBTI evaluation were in the sample studied. But what if people with a certain personality type are less likely to take a personality test? This type would not be accurately represented in the sample. And if one type is more likely to take a personality test? Those folks might appear more often in this sample than in the general population.

Still, let’s take a look.

Meyers Briggs personality test frequency

(Data from the Meyers Briggs Foundation)

If you lined up all of the personality types in order of their percentages, the types at the middle are ISTP (5.4 percent) and INFP (4.4 percent). If you fall within 5 percent of the population, are you unusual? Well, yes. In some regard, but only if the rest of the population falls in one category outside of that 5 percent.

In terms of rarity, we often think of rates of disease. According to the American Autoimmune Related Disease Association, about 5 percent of the population in Europe and North America have an autoimmune disease. With these diseases, (including celiac disease, rheumatoid arthritis, multiple sclerosis, lupus and type I diabetes) the immune system is attacking some part of the body. (In fact, my father had autoimmune hepatitis and vitiligo and died of pulmonary fibrosis.)

If 5 percent of the population is affected by autoimmune disease, 95 percent is not. This makes autoimmune disease seem kind of usual or rare. Actually, it’s not rare by medical standards. For a disease to be considered rare in the U.S., it must affect less than 0.06 percent of the population.

And as with all math, the context matters. There are 16 personality types.  If there were only three types, 5 percent is really rare. But with 16 types, well, 5 percent isn’t so unique. That’s because the other 95 percent is spread out among the remaining 15 types.

Now where this stuff gets really interesting is in certain populations. For example, in a 1992 study of college and research librarians, 11.5 percent were INTJ, while 0.8 percent were ESFP. These results definitely don’t square with the frequency in the general population. So you might be not so rare among librarians but more uncommon within the rest of the world.

I don’t mean to suggest that each of us is not a special snowflake. We are — but that’s not because of our personality types. As useful as these categories are, they certainly ignore a large part of the rest of what makes us who we are. (Meyers and Briggs knew this, of course, and their foundation works hard to be sure that the MBTIs are used ethically and responsibly.)

So go on with your special self. Fly your freak flag proudly. Just know that each of the personality types is interesting and unique in its own way. You are special, but not because of your personality type. There are just too many other possibilities!

Photo Credit: db Photography | Demi-Brooke via Compfight cc

Do you know what your MBTI type is? I love to hear about others’ personality types and how they understand them. Share your personality type stories in the comments section. Because you’re special. Just the way you are.

Math at Work Monday: Mina the Speech-Language Pathologist


Today’s interview is with Mina Greenfield.  She has been a speech-language pathologist for sixteen years.  I enjoyed hearing not only about the math involved in her job but also about her work with children on the autism spectrum.  People like Mina are becoming needed more and more as autism is on the rise. I’m so thankful that she has dedicated herself to this important job.

Can you explain what you do for a living?

I am a clinician in a private school for students on the autism spectrum. I work on interdisciplinary teams that include classroom teachers, teaching assistants, occupational therapists, and social workers. When most people think of a “speech therapist”, they think of kids that can’t say their R’s or S’s. However, my work takes a broader look at communication. Can they understand what they hear or read? Can they express their ideas? And can they use language to communicate effectively with others?

When do you use basic math in your job?

I use basic math in my job to calculate my billable hours (each 15 minute segment counts as a unit) and to compare my “scheduled vs. actual” therapy time for the week (i.e. I was scheduled to do 23.5 hours of therapy time, but a kid was absent so my actual time was 22.5). I also use math when scoring standardized tests and interpreting test scores on incoming reports. When looking at standardized tests, usually the mean =100 and the standard deviation (SD) is 15. Therefore scores between 85 and 115 are considered to be within the average range. If I read a report on a new kiddo and I see language scores that are in the 60’s or 70’s (or lower), I will be keeping a close clinical eye on him. Percentile ranks also make frequent appearances in assessments.

Do you use any technology (like calculators or computers) to help with this math? Why or why not?

I use a widget calculator on my desktop for daily and weekly billable hours. I’ve always been good at mental math so it makes that process much quicker. When scoring standardized tests, there’s a lot of basic addition to determine a raw score, but then you use the manual to look up corresponding scores which does not require math.

How do you think math helps you do your job better?

My ability to do mental math makes my job much quicker which I suppose makes me do my job more efficiently (better). I’ve been in the field long enough that I don’t have to “think” about standardized scores and what they mean. If I see a certain number, I know it indicates a certain strength or deficit.

How comfortable with math do you feel? Does this math feel different to you?

For my purposes, I feel comfortable with math all of the time. Again, I’m very thankful I’m good at mental math.

What kind of math did you take in high school? Did you like it/feel like you were good at it?

I took them all…Geometry, Trigonometry, Calculus, and AP Calculus. I also took statistics in college.

Did you have to learn new skills in order to do the math you use in your job? Or was it something that you could pick up using the skills you learned in school?

I picked up the math at my current job pretty quickly. I think compared to other professions, it’s “basic” math. (maybe?)

Questions for Mina?  Let me know, and I’ll pass them on.


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