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A while ago I took a Mensa supervised IQ test (in Vienna). Probably due to nervousness at the beginning of the test, I did extremely poorly on the verbal section. You can imagine how suprised I was after seeing my results today (sd = 15):
iqsc
Fred (guest) meinte am 22. Sep, 21:32:
Mensa test
I took the Mensa tests in 1982. I was between jobs, bored, and curious. So, the choices were go take the Mensa tests or try some experiments with explosives.

I, too, have a top 1% IQ. That was the first shock. The second was reviewing the IQ materials included and noting the bell curve for IQ distribution. To create that symmetry I must have a soul mate as far off the mean on the downside as I am on the upside. In my life I have known some of them.

In actuality the IQ curve is skewed at the lower end because low IQ is associated with severe medical problems and survival is less likely. 
Mahalanobis antwortete am 22. Sep, 23:35:
Same here.
I've been studying for too long and now I badly need a regime change... which includes having a girlfriend. Hedgefundguy immediately saw through my sinister plans:

HFG: Impregnate a 160 IQ chick and create an Uber-Stastny who will conquer the world with his evil genius (and buy you a nice house in the Alps).

Me: Was that so obvious?

HFG: I watch a lot of cartoons.
In actuality the IQ curve is skewed at the lower end because low IQ is associated with severe medical problems and survival is less likely.
What I'd like to know: What are the implications of constructing test such that scores follow a normal distribution? My gut feeling is that intelligence follows a bimodal distribution. But I'm not going to elaborate on this ;-D. 
Anon (guest) antwortete am 23. Sep, 18:51:
If the distribution of IQ test scores is gaussian, then there should be a positive (although small) probability of getting a negative score, which makes no sense. So, the fitted gaussian distribution must be a misspecification. Ok, one could use a truncated gaussian distribution instead, but it lacks motivation as it's not the exact limit given by the CLT, which I guess is the main reason of using the bell curve.

Those tail probabilities are of course very sensitive to the specification of the distribution... 
Mahalanobis antwortete am 24. Sep, 00:30:
Truncated Gaussian
I was told that on standard IQ tests (with sd = 15) one can't receive a score lower than 70 (~ 2nd percentile), i.e. one has to use a special test for severely mentally retarded people anyway.

Btw, assuming that the world is populated by 6.5 billion people and using a test with mean = 100 and sd = 15, only 0.085 people are expected to have an IQ below zero ;D 
Anon (guest) antwortete am 24. Sep, 17:32:
Yes, it's true, the probability is negligible. (maybe I should've done some calculations before claiming anything...)

On the other hand, the relevant Wikipedia article suggests that sd=24 is used too (where do they get these figures from?), and it gives:

R> pnorm(0, mean=100, sd=24)
[1] 1.545430e-05

so, approximately 1.55 in every 10000, which, admittedly, doesn't seem much, but in the full population it gives

> 6.5e9 * 1.545430e-05
[1] 100452.9 
Hedgehog (guest) antwortete am 25. Sep, 02:39:
Wikipedia is a minefield of errors
Wikipedia is full of errors (some of them benign and some, more serious, seem to have been planted there deliberately). Sd=24 in standard IQ tests is apparently one of that type. Unfortunately, many of those errors are hard to spot unless you already know the subject very well (in which case most probably you won't need to search for the info in Wikipedia). I learned by my own experience that it's worth the effort to double-check everything that you read in Wikipedia as long as it is of any importance to you.
However, I have to admit that Wikipedia is a great place to start when you have no idea where else you can get the relevant information. Wiki also contains many good (and mostly authoritative) links which can be used (among other things) to verify the information that you read. 
Mahalanobis antwortete am 25. Sep, 03:19:
AFAIK
Wechsler scale: sd = 15
Stanford-Binet scale: sd = 16
Cattell scale*: sd = 24

The "World Intelligence Network" (...) agrees.

*Cattell IIIB and the Raven´s Advanced Progressive Matrices (old form) 
Hedgehog (guest) antwortete am 25. Sep, 05:55:
Truncation of normal from below is likely to occur well above zero
Wow, the "World Intelligence Network" link that you gave looks quite impressive! And I was not aware about the Cattell scale (which shows that my knowledge of the subject is limited).
On a related matter, it seems like we can never observe extremely low IQ scores simply because it is impossible to collect ANY meaningful experimental data with regular IQ tests from the people who are severely mentally retarded. Even if an alternative methodology can be applied to test those people, it isn't clear whether the mapping of scores obtained by that methodology to those obtained by standard IQ testing would make much sense. In some sense, the truncation from below occurs naturally, at a level much higher than zero. 
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vicd84 antwortete am 19. Jun, 12:01:
Many people don't know about the real significance of the Mensa tests.. I met some who consider it just another test, like most you can find on the internet. I honestly think that this test should be advertized as it can lead to a better knowledge of the IQ of the people in the world and it's dynamic over the years. Maybe some promotional coffee mugs or t-shirts could do the trick, especially to the younger people! 
fool (guest) meinte am 23. Sep, 11:32:
ironically
Most people who think about their IQ are idiots. 
Teresa Lo (guest) meinte am 26. Sep, 21:54:
No worries
What you lack in extreme intelligence, you made up for with your looks. ;-) 
Mahalanobis antwortete am 27. Sep, 02:09:
nǐ hǎo
I admire your visual abilities. You must be at least a 5-sigma event.

I've seen your picture at Tradementors.com. Whatever you may lack, I'd marry you without hesitation! 
Teresa Lo (guest) antwortete am 28. Sep, 01:41:
No Worries
If only I were 15 years younger.... :)

T. 
Mahalanobis antwortete am 28. Sep, 04:16:
So
you are saying that the picture was taken 15 years ago? 
Teresa Lo (guest) antwortete am 28. Sep, 06:22:
The picture was taken last year, but still, you would be the Ashton Kutcher to my Demi Moore. ;-) 
Mahalanobis antwortete am 28. Sep, 17:21:
What
about a love affair? Have you ever been to Vienna? ;-D 
Teresa Lo (guest) antwortete am 28. Sep, 18:51:
Sounds like a plan...
I've never been to Europe other than pass through the Heathrow on the way to the Middle East.

My first webmaster back in 1998 was from Wien and had pictures handing all over the office. Seems like it would be a very romantic city to have a love affair in, unless you already live there, I suppose. 
Mahalanobis antwortete am 29. Sep, 01:01:
You're right
One's own backyard isn't the best place for having a love affair. My favourite places in Europe for having an affair would be Paris and Venice. But I can also imagine having dinner with you somewhere in Spain, say, at the Port Olympic in Barcelona. Afterwards we'd be strolling down the beach hand in hand while the waves lap gently at our feet, the stars dance and twinkle in the nighttime sky and the ocean glows with their reflection...

Since I'll be hanging around in Canada the coming summer, I'd suggest Québec city. I also remember some really nice places in Nova Scotia. Do you like lobster? ;-D

But everything would be much easier for me if you just come to Vienna... 
Teresa Lo (guest) antwortete am 29. Sep, 01:30:
Awwww...
...that is soooooo romantic. The description of Port Olympic reminds me of The Corniche in Beirut. It was glorious back in the day...

Speaking of Canada, those of us here in Vancouver tend to think of anything east of B.C. to be the badlands. I have seen the commercials on U.S. television about how wonderful Quebec City city is; ditto for Nova Scotia. So it would be nice to go and see it once.

But before we do all that, would you please check your email? :) 
Oli Rhys (guest) meinte am 20. Dec, 10:55:
Same Score!
Cool - we have the same score on the IQ!

I took mine a few years ago now, but Mensa were nice enough to send me a little certificate to put on the wall!

Not sure how relevant IQ scores are in today's world, intelligence seems to have become a major disadvantage as you can see the major holes in the arguments most people take for granted, and you become a heretic for pointing them out! :) 
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