# How different are various IQ levels to each other, ie 100 vs 110,...? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 8, 2022, 12:57pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677 "2022-03-08T12:57:47Z")\ **Posts on this page:** 14\ **Page:** 6
**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\ **Post date:** [March 10, 2022, 4:33pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/101 "2022-03-10T16:33:44Z")
> [@Pardel-Lux](#): > > Just an aditional question, if you allow: does that mean that my impression I got better at IQ tests with practice was an illusion? > [@Kelby](#): > > practice effects Yes, practice effects are a big thing. That is one of the reasons that test preparation for the SAT (and similar) can be useful. The test retest reliability means that your scores across multiple time points are all highly correlated, but not necessarily the same. > [@lobotomyboy63](#): > > Also, I found this: > > > The general public tends to misunderstand the kinds of IQ tests that are administered by psychologists […] Because she is having trouble in school, my daughter took an IQ test in a clinical setting for exactly those reasons, Anybody talking to her would know she does not have an intellectual disability, but a standardized test can put a number on it, which communicates to anybody looking at her file that this child is having difficulties for reasons other than intelligence. > [@iamthewalrus\_3](#): > > Now, this could just be someone taking the piss, or maybe they took a nonsense test or made some other dumb error that made their score not representative. But this does not look like something written by someone who would struggle with “how would you have felt if you didn’t eat?” This is my opinion, and probably better suited for the “what do you believe without evidence thread,” but a lot of people hate the _idea_ of IQ, because they hate individual differences, the idea that individual differences can be quantified, and that some of these differences can be important. People are different. Some of those differences can be easily measured, such as height, weight, preferred way to pronounce GIF, and even IQ. Some of these measured differences can have tremendous consequences for the people who end up on the wrong end of the distribution. That really upsets some people, who equate what I just said with racism and eugenics. To be completely fair, eugenicists _love_ IQ and other measurable individual differences because it can give them an air of scientific legitimacy to support their racist views. So, people will poke at IQ, g, and other things, pointing out legitimate flaws, exceptions, and just making stuff up in attempts to discredit it. We’ve all seen similar behavior around things like vaccinations, climate change, etc., and they’re often just as insightful as people asking “if we have global warming, why is it so cold outside?” ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [March 10, 2022, 4:34pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/102 "2022-03-10T16:34:17Z")
> [@Johnny\_Bravo](#): > > It’s kind of like crossword puzzles. A fair portion of their difficulty is wrapped up in parsing the clues correctly. If you do a bunch of them you start to see the patterns and understand the clue structure. You get better at the kind of thinking that is specific to performing that task. It doesn’t mean you’re getting smarter. I suppose it depends on your definition of “smart”; but I’d say that, if you’re getting better at a particular kind of thinking, you _are_ getting smarter, if only in one particular, limited way. (Kind of like, you’d be getting stronger if you were strengthening one specific muscle.) ---
**Author:** ![Johnny\_Bravo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_bravo/32/493_2.png) [@Johnny\_Bravo](https://boards.straightdope.com/u/Johnny_Bravo)\ **Post date:** [March 10, 2022, 4:40pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/103 "2022-03-10T16:40:25Z")
> [@Thudlow\_Boink](#): > > I suppose it depends on your definition of “smart”; but I’d say that, if you’re getting better at a particular kind of thinking, you _are_ getting smarter, if only in one particular, limited way. No doubt. In this case I meant “smart” in the sense of the measurable, relatively static traits we’ve been discussing. I could’ve been more clear. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [March 10, 2022, 4:50pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/104 "2022-03-10T16:50:25Z")
Some of the recent comments double on the possibility of a person with a measured IQ of 90 becoming a physician. I will argue yes possible. Slates are not blank and there are inherent differences in intelligences. (Yes the plural form is intentional.) Not sure how convinced I am of _g_ per se but I am convinced that all tools designed to measure _g_ are limited and minimally have significant cultural biases. There are definitely people whose measured IQ on the accepted instruments are lower than their true intellectual capacities. And the other direction as well. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [March 10, 2022, 10:10pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/105 "2022-03-10T22:10:49Z")
> [@echoreply](#): > > This is my opinion, and probably better suited for the “what do you believe without evidence thread,” but a lot of people hate the _idea_ of IQ, because they hate individual differences, the idea that individual differences can be quantified, and that some of these differences can be important. I think (and if I’m wrong, apologies for putting words in your mouth) that you’re suggesting that the IQ-83 guy might not really have a low IQ but is writing that letter in an attempt to discredit the concept of IQ. Certainly possible. I think that IQ is real and important, but it’s not the _only_ important thing, and of course something that is statistically valid is not always valid for an individual. The map is not the territory. I’m sure that it’s challenging to have an IQ of 90, but I also think that the claims made in the 4chan screenshots are total nonsense. Looking again at the link I shared, I hadn’t noticed before that it was written by Scott Alexander of Slate Star (and Astral Star) Codex. I respect his writing and thinking a good deal, and he’s a trained psychiatrist, so this stuff is at least a little in his wheelhouse. It’s also worth spending more time with the chart at the end, which is from a legitimate scientific paper on IQ, and clearly is not consistent with the 4chan nonsense. Kindergarten/elementary teachers have a 10th percentile IQ below 90. I am absolutely positive that ~15% of kindergarten/elementary teachers do not struggle to comprehend “how would you feel if you hadn’t eaten yesterday”. Materials and design engineers have a 10th percentile just above 90. I’m not sure exactly which jobs count as material and design engineering, but I find it hard to imagine that ~10% of them can be done by people who struggle to contemplate a theory of mind for themselves a day ago. ---
**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\ **Post date:** [March 11, 2022, 12:36am UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/106 "2022-03-11T00:36:55Z")
> [@iamthewalrus\_3](#): > > you’re suggesting that the IQ-83 guy might not really have a low IQ but is writing that letter in an attempt to discredit the concept of IQ Yes, thanks for stating it clearer than I did, that is what I mean. I don’t doubt he tested at an IQ of 83, if that’s what he claims. I once tested with an IQ of 1, and my brother with an IQ of 0. I thought the test was stupid, and only answered 1 question, my brother was told to only answer what he was sure of, so he didn’t answer any. The point being, that a single score on a single test from a single subject doesn’t demonstrate much of anything. Like I said, it’s the equivalent of “how can there be global warming, it’s cold outside.” Lots of scores on lots of subjects and finding lots of exceptions just proves that the correlation between IQ and whatever is not 1.0. I think this quote from that article is very important for people to remember: > The chart perfectly demonstrates how IQ is both statistically reliable and individually unreliable. On average, intellectually demanding occupations like college professors have higher IQs than less demanding occupations like janitors. But individual janitors are sometimes higher-IQ than individual college professors. And almost every profession draws from a wide range of IQs. The average professor is pretty smart — but a nontrivial number have below-average IQs. IQ, BMI, and other things can work well on a population level, but really fall down on an individual level. BMI can be a powerful predictor of heart disease in a study, but used for fat shaming on an individual level. IQ can be a strong predictor of success, and used as a basis to commit forced sterilization under evil eugenics plans. So if I know nothing more than “that person’s IQ is 90” I’m going to say their a poor candidate for college professor. If all I know is “that person’s BMI is 32” I’m going to say they are at risk of heart disease. It’s easy then to do the reverse, too. Look at a bunch of people in jobs that seem to require high IQs, and then find the ones that have records of low IQs, or find a bunch of people with low BMIs, but heart disease, and then write a gotcha article. None of that means IQ or BMI is invalid, or a useless predictor, just that the correlation is not 1.0. Or another example. On average, men are taller than women. Not _all_ men are taller than _all_ women, so a short man and a tall woman doesn’t prove anything. It doesn’t mean the concept of height is invalid, or that “men on average are taller than women” is incorrect. ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [March 11, 2022, 1:14am UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/107 "2022-03-11T01:14:13Z")
> [@iamthewalrus\_3](#): > > I assume that the vast majority of nonsense “IQ” tests are intended to be ego stoking, so I put a bit more credence in the possibility that Mr. 83 took something more legitimate. That’s very possible. It’s also possible that the test “writers” slapped something together and it spit out a very low number if the person only answered a few questions. If they didn’t anticipate people skipping questions (or thought that no answer meant the person couldn’t answer), they would assign 0 as though they missed it, etc. > [@DSeid](#): > > Some of the recent comments double on the possibility of a person with a measured IQ of 90 becoming a physician. > > I will argue yes possible. I once knew a guy who took college courses to become a forest ranger. He was a nice guy but not the smartest person I ever knew. I wouldn’t be surprised if it took him six years to complete a four year degree, but a lot of people need some extra time. A lot of us thought he was crazy because the job doesn’t pay well, but it’s his life etc. What if you took 100 guys who loved the park system, forests, etc., and who had bought into getting an education to realize their dream…and you also took 100 guys who loved medicine, health care, and who had bought into getting an education to realize their dream of becoming a doctor? Check back in ten years. How many became forest rangers, and how many became doctors? I found this: > Many Americans may not know that the number of doctors is essentially set by Congress. Each year, the Centers for Medicare & Medicaid Services, or CMS, [provides payments to hospitals](https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/AcuteInpatientPPS/DGME) to hire their residents—the crucial bridge that medical school students must take to becoming licensed physicians. Because the number of residencies is tantamount to the final number of doctors, the federal government has enormous leverage over the number of new physicians that enter medicine each year. [Source](https://www.washingtonian.com/2020/04/13/were-short-on-healthcare-workers-why-doesnt-the-u-s-just-make-more-doctors/) And there’s that joke: if you and I are being stalked by a grizzly bear, I don’t have to outrun the bear—I only have to outrun you. In other words, lots of folks could study to be forest rangers and all could pass. Doctors, no…there’s a limiting factor. Even if they’re all brilliant, that fixed humber of residencies apparently is your limit. And your fellow students are your competition. Got a 90 IQ, Mr. Hopeful Doc? Here’s your IQ 120 competition…he picks up things faster, has a lot of previous knowledge to connect it to, and he’s very quick thinking on his feet. IANAD. Feel free to fight my ignorance. ---
**Author:** ![peccavi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peccavi/32/388_2.png) [@peccavi](https://boards.straightdope.com/u/peccavi)\ **Post date:** [March 11, 2022, 2:31am UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/108 "2022-03-11T02:31:05Z")
> [@iamthewalrus\_3](#): > > Looking again at the link I shared, I hadn’t noticed before that it was written by Scott Alexander of Slate Star (and Astral Star) Codex. I respect his writing and thinking a good deal, and he’s a trained psychiatrist, so this stuff is at least a little in his wheelhouse. If you’re interested in digging into the data and getting some insight into what confounding factors might be taken into account, here is a link to Robert Hauser’s original paper, _Meritocracy, Cognitive Ability,and the Sources of Occupational Success_. It is the source of the bar chart in the article. There are also a lot more charts of this type at the end of the paper. > **[2002-hauser.pdf](https://gwern.net/doc/iq/ses/2002-hauser.pdf)** > > 1259.31 KB ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [March 11, 2022, 5:40am UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/109 "2022-03-11T05:40:11Z")
Yes getting into medical school is a competition. There are tons of students starting college hoping to get one of those spots and only a very few of those students will end up as physicians. The being chased by the grizzly bear analogy though is where your understanding is insufficient. One, you are missing my point in the post you reference. Having higher _g_ (assuming _g_ actually exists as a thing other than as defined by your performance on the test stated to measure it) can certainly make it easier to get top grades and to test well on the MCATS. I am however not convinced that IQ test scores necessarily always measure whatever _g_ is in an accurate manner. The test is not always a valid measure of whatever _g_ is, and historically has been prone to cultural biases. Then there is simply that higher intelligence alone is not the metric of who outruns the bear and who does not. I am 100% confident that there were many starting off with ambitions for med school the same college freshman year I made that choice with higher _g_ than I have who did not make it into med school. And some with _g_ less than I have who did. Yes there is some soft threshold of sorts on the low side, but above that there are many other differentiating factors and paths to being chosen for one of the spots. Someone testing as 90 may still _in reality_ be smart enough, and have other characteristics that serve them better in the competition than someone with slightly more _g_ than they have. A good doctor does need to be smart enough and above that there are many other factors that create a better doctor, and then those factors vary by specialty. Highest possible intelligence doesn’t necessarily correlate with being the best at the job. In fact one of the classic gags in med school is that you want to avoid both the physicians who were at the very top and the bottom of their class. Of course those of us who were neither were the ones telling that gag. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [March 11, 2022, 5:53am UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/110 "2022-03-11T05:53:39Z")
Pages 27 and following are specifically relevant to this discussion btw. ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [March 11, 2022, 7:53am UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/111 "2022-03-11T07:53:10Z")
> [@Wendell\_Wagner](#): > > To be more exact, for there to exist someone with an I.Q. of 300 (which is 20 standard deviations from the mean), there would have to be something like 7 followed by 176 zeros people who ever existed for one of them to have an I.Q. of 300. That’s more than the square of the number of atoms in the observable universe. To nitpick myself, an I.Q. of 300 isn’t 20 standard deviations above the mean. It’s 13 and a third standard deviations above the mean. I’ll let someone else calculate how ridiculously improbable that is. ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [March 11, 2022, 1:40pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/112 "2022-03-11T13:40:54Z")
> [@DSeid](#): > > Someone testing as 90 may still _in reality_ be smart enough, and have other characteristics that serve them better in the competition than someone with slightly more _g_ than they have. You’ve been there; I haven’t. And I know from reading many of your posts that you’re pretty circumspect in your thinking. Ignorance fought, thanks…I’ll have to ponder further. ---
**Author:** ![iamthewalrus\_3](https://avatars.discourse-cdn.com/v4/letter/i/258eb7/32.png) [@iamthewalrus\_3](https://boards.straightdope.com/u/iamthewalrus_3)\ **Post date:** [March 11, 2022, 2:58pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/113 "2022-03-11T14:58:21Z")
Thank you. I tried to follow the link in the article but it was dead and I didn’t pursue further. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [March 11, 2022, 3:35pm UTC](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677/114 "2022-03-11T15:35:00Z")
> [@msmith537](#): > > Anyhow, as I recall, most of the questions weren’t “multiple choice” such that you could guess at them. Some were timed responses like solving a puzzle or recalling a spoken string of numbers or letters. I was given an IQ test at 7 or 8 years old by the child psychologist who was treating me for depression, but I wasn’t told that’s what it was. It seemed like a series of puzzles and games, which wasn’t _that_ different from some of the other therapy activities for little kids. [Previous page](https://boards.straightdope.com/t/how-different-are-various-iq-levels-to-each-other-ie-100-vs-110/960677.md?page=5)