Yeah, I consider myself somewhat intelligent, and, like I said, I believe my son is quite a bit smarter than me. But 150? That’s like Lex Luthor level IQ 
Whatever the criticisms of the accuracy of IQ tests, comments like these that crop up in every thread on IQ tests suggest that perhaps many people who criticize them do not know what they are designed to measure. The phenomenon that they try to measure is uncontroversial and absolutely real. It is the correlation in performance among different types of cognitive task. A factor called general intelligence (g) explains about half of the between-individual performance difference on any given type of cognitive challenge.
There are certainly many valid criticisms of whether IQ tests are effective at measuring g, but to suggest that g is not objectively real or is not important is mistaken.
Thank you for that helpful clarification. In pointing out their limitations, I certainly didn’t mean to imply that IQ tests weren’t measuring anything real or important.
Yes, that’s VERY impressive.
Impressive enough to get you to buy the report they’ll sell to you to show to your friends.
They are…in certain educational and legal contexts. The tests are an integral part of assessments to determine eligibility for special programs/services and mental competency.
But I don’t think looking at just your percentile gets to the heart of the OP’s question, which is partly asking about the variance of the distribution. How much smarter is the top quartile of the population relative to the bottom quartile?
It’s hard to know just how to think about this. When we’re “on the inside looking out” as part of the human population, perhaps we tend to overestimate the differences among us? We tend to focus on the unusual achievements of extreme outliers like Einstein, and forget that virtually of us carry out remarkable cognitive tasks like acquiring language that we don’t “notice” simply because we all seem to do it so easily and without conscious effort.
A chimp’s IQ has been estimated at around 20-25. So perhaps you could argue that the difference between the human species and any other species is much greater than the differences among individual humans.
I don’t believe I suggested that. I am absolutely suggesting that the IQ score, by itself, has little value. I would happily do away with it altogether; the people who really need the data informed by the IQ score generally have access to full psychological workups that give actual, actionable information about how to help the individual.
Not going to quote the whole Wikipedia article linked above, but to summarize: the practical validity of IQ scores as a predictor of any outcome is controversial, and the statistics involved are daunting.
In general, it appears that there is a significant correlation between IQ scores and outcomes such as academic achievement and job performance, though the correlation decreases for any particular subgroup. For example, someone with an IQ of 90 is unlikely to get into medical school, but a doctor with an IQ of 130 isn’t likely to be much more successful than one with an IQ of 120.
So it seems my WAG above might be approximately correct, that around 20-25 points is about where we could probably say “this group of people, on average, are pretty clearly not doing as well at life as this group”. But even then individual experience would vary widely, and the correlation would break down as you approached either extreme of the Bell curve.
Yes, the differences would probably be less noticeable in the middle of the range.
IQ’s from 90 to 109 are considered within the “Average” range.
But one with an IQ of 90 would be clearly functionally different than one with 70.
The other point you highlighted about doctors is probably significant for many professions. It suggests a model where there is some threshold of cognitive ability that is necessary to become (say) a doctor, and that if you are below that threshold, other personality traits are irrelevant - you just aren’t smart enough to do it. But provided you are above that qualifying cognitive threshold for a given profession, being extremely smart decreases in importance relative to other traits like dedication, ambition, emotional stability. There are going to be some professions where this isn’t true, but I suspect it’s a good model for many.
I really doubt that a person with an IQ of 80 could get a PhD. But I once knew someone with a self-proclaimed IQ of 100 who wanted to get a PhD in some biological science. Whatever it was required a course in physical chemistry, which in turn required calculus. He was prepared to take an entire year doing nothing but studying calculus and another entire year for p-chem. I lost track of him, but I hope he made it. He sure was motivated.
Yes, I agree, that model seems to fit both the data and my life experience.
An Ed Psych professor once helped illustrate this for us, using the example of medical doctors.
He asked for a show of hands on the percentage of doctors having IQ’s above 150, 140, etc.
“How many doctors have IQ’s above 100?” Virtually all hands raised.
“How many have IQ’s above 90?” All hands raised.
I can assure you, he said, that statistically there are M.D’s included in the under 90 group.
I don’t really understand this, in particular the “statistically” comment. Is he claiming that there must be doctors with IQ below 90? Why?
Obviously speaking of IQ tests I didn’t talk about online apps, but about actual tests used by psychologists.
I have diagnosed adhd and during one of my visits to psychologists I did a test which consisted mainly of general knowledge open ended questions, for example “why is leather used as a material for making boots?”, “what is marriage and why do people marry”, beginning from simple questions like which country we are in, to questions about classic music compositors and so on. There were math questions that also had working memory questions, I was given a number and had to name other numbers that should go in sequence, like 2, 4, 8, 16, but each question being more complex than the previous. There were some other types of questions, but I only remember these few examples.
There is probably a far more complex test, but even a test like that one makes sense to me, it doesn’t just make you randomly choose A, B or C on a weird combination of shapes, like most online tests, but it tests your reasoning and logic in the real world, plus the speed of your processing, both for math and general questions.
As for janitors, it was an example of a job that usually has a very small pay, no upwards potential and can be done even without a high school diploma. It’s not a type of a job most people would willingly choose if they had a choice. Most people do those kind of jobs because they can’t find other jobs.
Interestingly, the wiki article says that the correlation between high IQ and working in a profession generally perceived as “prestigious” is quite a bit higher than the correlation between IQ and actual income.
Well, let’s propose that the average overall IQ of doctors is 120. That’s the bottom of the superior range.
Placing a normal curve over this population with the average set at 120 would mean that the score two standard deviations below the mean would be 90.
That leaves about 2% of the population of doctors below 90.
Funny you mention janitors:
I suspected that’s what you meant. But I think your Ed Psych professor was wrong. There is no reason that the distribution of doctors’ IQs must be normally distributed.