IQ stands for intelligence quotient because originally IQ was calculated as the ratio of mental age to chronological age, so if you were a six-year-old who cognitively functioned like the average six-year-old, you had an IQ of 100, because you were functioning at 100% of your chronological age. By contrast if you were a six-year-old who was functioning like a four-year-old, your IQ was 66, because your development was only 66% as fast as it should be, and you were sent to what were then called EMR classes.
This was a beautifully elegant concept but there were a few problems. The first is all of us are 0.75 years older than we think we are since we grew in the womb for 9 months. The age ratio method would have made more sense if they had added 0.75 to both the chronological and mental ages and I suspect the distribution would have been more normal.
The other problem is cognitive growth is not linear function of age throughout the entire maturation process.
“Some guy” writes:
Does it really matter if it’s not linear though? If someone scores as the average 10 year-old then it indicates they have the drawing IQ of a 10-year old, which seems more useful than a subjective number.
What’s more useful information about a man’s height? That he’s as tall as the average 10-year-old, or that he’s 1.3 feet shorter than the average man. Both are useful, but the advantage of creating a scale that is independent of age is that it has a much higher ceiling. On the old Stanford-Binet, scores stopped increasing after age 15, so how do you assign a mental age to someone who is smarter than the average 15-year-old?
The old Stanford-Binet got around this problem by arbitrarily extending the mental age scale beyond 15, so Marilyn vos Savant was able to claim an IQ of 228, because she scored a mental age of 22.8 at age 10, even though there was no such thing as a mental age of 22.8 on a test where mental growth peaks at 15.
This makes about as much sense as telling a 19-year-old seven-footer they have a height age of 92, and therefore a Height Quotient of 484, after all the average male height only increases by 0.2 inches from 19 to 20, so if height didn’t plateau, at that rate it would take the average man until his 90s to reach seven feet.
“Some guy” continues:
Presumably they still used this system to see if people scored averagely for their age, but had to first to figure out what the average for each age was anyway.
A related question: Is the mental age concept still applicable to modern IQ tests even though they’re not based on it? Let’s say 10-year old scores 130 on the WAIS. 2 SD above the mean on a 16 SD mental age test would be 132. Can that child be assumed to have the same IQ as the average 13.2 year old?
Put it this way. If a ten-year-old scored like an average 13-year-old on every subtest of the WISC-R, he’d get a full-scale IQ of 126, which is similar to the 130 you’d expect from the age ratio formula. On the other hand if a 10-year-old scored like a 15-year-old on the WISC-R, he’d get a full-scale IQ of 134, which is much less than the 150 you’d expect from age ratios.
And yet if a six-year-old scores like a nine-year-old on the WISC-R he gets a full-scale IQ of 143. So the same ratio IQ equates to different deviation IQs depending on what age it’s obtained (or what test it’s obtained on) which makes it a problematic index.
It probably agrees most with deviation IQ when both the chronological and mental age are no lower than 4 and no higher than 12, since that’s probably the most linear developmental period.
Pumpkin Person 
peepee should start cataloging instances of polyphenism.
1. brando transitions from sexiest man in the history of the world to hideous joke.
2. ???
so i imagine lolberts say…
“so you want a world where ugly people can’t BUY love?”
yeah!
exactly!
that’s EXACTLY what i want…
because the very idea of “BUYING love” is an oxymoron.
do you think my irish setter thinks that ugly dogs are lazy?
NEVER underestimate the power of money
NEVER say that money can change REALITY!
Money is a paper… Never understimated human imbecility.
and pill’s theory is total bs.
all one need do is click on the “see also, famous cases” in wikipedia to see that…if anything…those families which suffer from huntington’s are LESS accomplished than average.
the tay-sachs heterozygotes have not been investigated sufficiently iirc.
but i don’t mean that LOVE is a thing which SHOULD be desired.
as far as man-woman…sexual desire…goes…
this is a thing one should be ashamed of.
For there are some eunuchs, which were so born from their mother’s womb: and there are some eunuchs, which were made eunuchs of men: and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven’s sake. He that is able to receive it, let him receive it.
supposedly yul brynner was a jew…i doubt it.
the sexiest man is a man.
it’s bizarre and SAD.
women can CONTROL men.
Thanks for taking the time, pumpkin!
Is there anyone else who writes entertaining general interest stories about IQ like you, rather than more scientific stuff?
Seems like estimating mental age from IQ can still be quite handy to get a rough idea of how smart someone is. Even the 10-year old who scores like a 15-year old has a correlation of 34/50=0.68 with their true mental age.
It would be interesting to do a graph with actual age on one axis, mental age on the other, and the WISC score that would follow in the middle.
But that’s probably a lot of work.
There are a lot of people who blog about IQ occasionally but the only other who regularly does so that I can think of James Thompson:
http://www.unz.com/jthompson/
Among people who are the same age, ratio and deviation IQs correlate perfectly in the sense that one’s rank order on one is perfectly matched by one’s rank on the other, but ratio IQs tend to be systematically more extreme (i.e there are many people with ratio IQs well above 200 but virtually nobody with deviation IQs that high)
The graph is a good idea. I should do it someday. In the meantime this source might be of interest:
http://miyaguchi.4sigma.org/BloodyHistory/ratioiq.html
Thanks for the link Pumpkin!
The average correlation between mental age and WISC scores from your three examples is .80, so pretty good.
The average correlation between mental age converted to DIQ, as per your link, and WISC scores from your three examples is .90
Especially the 6-year old who scores like a 9-year old is accurate, with DIQ being 143.2 and WISC giving 143.
I forgot Pumpkin, did you ever mention what you did for a living?
i would have told her…
very hard to talk to as she was a senior and i was a sophmore.
“you can call the police. but i’m not gonna see you again ever…”
and then what?
“i want to eat you.
and what i don’t eat, i want to feed to my dog.”
the point is i don;t know what i would say.
i met her brother a few years later. i didn’t tell him how i wanted to eat his sister.
he died in a ski-ing accident at age 24.
i was working for anthem in LA when i heard.
…wish i’d said something…even if it sounded rape-y.
but what do you say?
the object of adoration is 99% of the time not going to adorate YOU.
so you just say…
i think you’re almost as pretty as oprah.
Pumpkin, if you practice some really hard problems in Physics, but you completely fail at them, would you get any better at doing the easier problems you could never do?
I think it depends on the concepts involved. If the concepts line up, then youre all set.
But if you’re failing, you aren’t really improving anything, right?