This is SCIENCE?? RO: Stupid media and IQs

[Blaster_Master]

[QUOTE=gazpacho]
The 15 point standard deviation of the normalized IQ scores has nothing to do with how accurately IQ can be measured. In fact it seems to me that the OP does not understand IQ and measurement statistics very well. Confidence interval has a few key parameters.

1. The assumption of a normal distribution. (you can use other distributions but most times people are talking about a normal distribution)

2. How good your confidence needs to be. Typically people use 95% but others can be used.

3. sample size

A given test can have a certain amount of accuracy in it. For example say I take an IQ test and get a score of 99.5 and the makers of the test say that it is accurate to ± 1.2. They are saying based on this test we are 95% confident that the real IQ is between 98.3 and 100.7.
[/QUOTE]

I’m glad someone made this point about confidence intervals.

I also wanted to point something else out from the OP:

I spent ten seconds looking up IQ on Wikipedia, and it confirmed what I knew from my one psych course twenty seven years ago. IQ test raw scores are normalized to a mean of 100 points and a Standard Deviation of 15 points.

Here is (I think) the relevant quote from thewikipedia article:

…it was replaced by a projection of the measured rank on the Gaussian bell curve with a center value (average IQ) of 100, and a standard deviation of 15 or occasionally 16.

IOW, the Standard Deviation that is used on the curve has nothing to do with the accuracy of the IQ test, it’s simply a way of scoring the test so most people score closer to a score of 100 and fewer score far away from 100. That is, it has nothing to do with the actual distribution of the scores (if they are actually normal).

What you’re really interested in is how accurately the test measures where you belong in this distribution. That is, if the Ground Truth of your IQ is 125, then you should expect that the IQ test should score you with a mean of 125, not 100. Thus, what you really need to compare is the samples taken for the different aged children and compare them using the Standard Deviation of the test that was used. I imagine they have tests with error FAR less than 15 points.
Further, we can use a t-test to determine how different two populations are, and the differences can be made more clear by either having smaller standard deviations OR larger populations. Thus, a difference of 2.3 points could be legit, but I’d have to see the paper to make sure.

[Colibri]

[QUOTE=John Mace]
Was there any attempt to understand if conditions peculiar to Norway (or Northern Europe, or…) might be at play? Did the authors caution about saying whether these conclusions would tell us anything about IQ in, say, China or Japan?
[/QUOTE]

No. The article itself is very brief. Here it is in full:

Explaining the Relation Between Birth Order and Intelligence

Note that the main point is determining if the effect is gestational or social. The birth order effect itself was first claimed by Sir Francis Galton, Darwin’s cousin and one of the founders of modern statistics, in 1874. The effect has since been confirmed in numerous studies, but I do not know the extent of research on the subject in different cultures and social systems globally.

[Rubystreak]

I noticed that children who were not born first, but who became the eldest child in the family due to the first child dying also had the higher IQ:

We show that intelligence quotient (IQ) score levels among nearly 250,000 military conscripts were dependent on social rank in the family and not on birth order as such, providing support for a family interaction explanation.

The implication here is that the IQ difference is due to nurture, not nature. That’s interesting, because the upshot then is that parents treat kids differently and somehow foster greater intelligence in their first children. Is it because the first child has time alone with the parents before the next child comes along? I would think a study of how only children compare to eldest siblings might show if this is true.

Another question comes to mind. At what point is IQ fixed? How old does the child have to be when he becomes eldest, if his older sibling dies, in order to reap the benefits of his changed social rank within the family?

[Colibri]

[QUOTE=Rubystreak]
Is it because the first child has time alone with the parents before the next child comes along? I would think a study of how only children compare to eldest siblings might show if this is true.
[/QUOTE]

I have read various ideas on this subject. One hypothesis is basically the one you suggest - the eldest child spends some time in an environment in which the average age of the entire family is higher than for any subsequent children. Another is that the eldest child learns more in the process of teaching his younger siblings.

[Gala_Matrix_Fire]

FYI, this study only concerned boys. No girls.

I am not a scientist, but it seems to me that this is of very limited utility. Extremely limited utility. Okay, I agree with the OP that it’s useless.

[Colibri]

[QUOTE=bluethree]
FYI, this study only concerned boys. No girls.

I am not a scientist, but it seems to me that this is of very limited utility. Extremely limited utility.
[/quote]

You think that the finding that differences in IQ is in part due to familial social factors, rather than genetic or gestational, is almost entirely irrelevant? Even if females have an entirely different pattern, certainly a finding of such a pattern for half the population is of some interest with regards to the development of IQ.

Okay, I agree with the OP that it’s useless.

The OP completely misunderstood the entire point of the study, as well as the statistics behind it. What is your reasoning for why it is “useless”? I trust it is not the same as the OP’s.

[Terminus_Est]

[QUOTE=Colibri]
No. The article itself is very brief. Here it is in full:

Explaining the Relation Between Birth Order and Intelligence

Note that the main point is determining if the effect is gestational or social. The birth order effect itself was first claimed by Sir Francis Galton, Darwin’s cousin and one of the founders of modern statistics, in 1874. The effect has since been confirmed in numerous studies, but I do not know the extent of research on the subject in different cultures and social systems globally.
[/QUOTE]

Don’t forget to check out their supplementary material, including a full description of the sampling methods and statistical analysis. They even give the raw output of the multiple linear regression analysis (I’ve never seen that before).

[BrainGlutton]

Related GD thread.

[DSeid]

Very cool study on a fairly esoteric question. The oft documented very minor but real superior performance of eldests on standardized IQ tests is indeed due to their social ranking and clearly not to some biological effect of the mother being multiparous or the father’s advanced age. As to the significance of those IQ points, one might read the accompanying Perspective

Critics might still argue that the mean IQ difference documented between a Norwegian firstborn and a secondborn is only 2.3 points. Such a modest difference, however, can have far greater consequences than most people realize. For example, if Norway’s educational system had only two colleges–a more prestigious institution for students with IQs above the mean, and a less desirable institution for all other students–an eldest child would be about 13% more likely than a secondborn to be admitted to the better institution (the relative risk ratio), and the odds of a firstborn being admitted would be 1.3 times as great. In medicine, new therapeutic benefits of this magnitude often make front-page headlines. In addition, such differences in opportunities gained or lost inevitably accumulate over one’s lifetime.

The Perspective goes on to note some other intersting facts including that younger sibs actually do better when young but that apparently the opportunity to tutor the younger sibs drives the eldest up as time goes on. Only childrren have no such benefit and do not do as well.

… younger siblings tend to score higher than older siblings when tests of intellectual ability are conducted under the age of about 12 (6, 7). In more than 50 previous samples, there is a significant tendency for IQ disparities by birth order to reverse direction as children get older.

Zajonc’s own confluence model of intellectual ability provides a possible explanation for this curious age-related reversal in birth-order effects. According to this model, the family’s overall intellectual environment embodies a dynamic aspect that includes all of its members’relative contributions. For example, the intellectual environment of a firstborn at, say, age 7 is actually less favorable than the environment of a 2-year-younger sibling at the same age. This is because the younger sibling, being linguistically and cognitively less mature, degrades the firstborn’s intellectual environment, whereas the older sibling enriches the secondborn’s environment. To explain why older siblings eventually tend to overtake their younger siblings in intellectual performance, Zajonc’s model posits a tutoring effect, which kicks in as older siblings begin to teach what they know to their younger brothers and sisters. Through the organization and expression of thoughts, teaching younger siblings is posited to benefit the tutor more than the learner, especially since lastborns have no one to tutor.

Given the latest findings from Norway, it is useful to compare the features of various competing theories about birth order and intelligence and to assess how they now stack up. These alternative explanations include family resource dilution models (of which the confluence model is a sophisticated variant), theories about prenatal influences, and “admixture” theories asserting that birth-order effects are spurious products of uncontrolled confounding influences. As shown in the table, resource dilution models and the confluence model both do well in providing possible explanations for birth-order differences, as well as for other family-related effects in intelligence (8). For example, both models are consistent with the fact that children without siblings, who are more likely than other children to grow up in single-parent homes and who also lack a sibling to tutor, generally exhibit lower test scores than firstborns having a younger sibling.

FWIW

[Chief_Pedant]

[QUOTE=Typo Knig]
Google news is all atwitter with Moron Media - um I mean Mainstream Media - reports on newly published study claiming that firstborn children have higher IQs than their later-born siblings.

I should pit this because I think IQ is bullshit - at best it’s an extremely coarse filter to identify children who need academic help in grade school. At worst, well read Stephen Jay Gould’s The Mismeasure of Man.

But I’m pitting this because the grand conclusion of the study is that the IQ difference between oldest and youngest children is … drum roll please …

2.3 points.

What the fuck?!?!

I spent ten seconds looking up IQ on Wikipedia, and it confirmed what I knew from my one psych course twenty seven years ago. IQ test raw scores are normalized to a mean of 100 points and a Standard Deviation of 15 points.

So anyone who is educated enough to know that “Standard Deviation” refers to statistics and not oral sex should immediately understand that 2.3 IQ points difference with an SD of 15 points is not significant, not worth talking about, not worth the ink it’s printed with, not worth the paper it’s printed on, not worth your time, and certainly not worth the electrons I’m expending now.

2.3 points! I could have a bigger difference between two tests taken on successive days.

It’s bad enough the Moron Media repeated this story. Every election cycle when the MM reports that candidate A has a “firm” lead of 2 points in an opinion poll with a 4 point margin of error, I give up anew on their understanding of, and their ability to explain, statistics. It makes the baby Carl Friedrich Gauss cry. The Mainstream Media is dumb. I know this. It still pisses me off.

But then I saw the study was published in Science magazine.

This is Science? This got past a peer review at the American Association for the Advancement of Science?? You have got to be fucking kidding me! I’m not saying psychology isn’t, or can’t be scientific. I am saying that researchers who claim that a 2.3 point IQ difference shows anything are kidding themselves, and wasting everyone’s time. At best the study can claim there is NO significant difference in IQ due to birth order. At fucking BEST.

Instead, between the exaggerated claims of the researchers and Moron Media’s endless parroting, millions of younger sibs are going to feel a bit stupider tonight. They aren’t. This “study” that supposedly shows they are dumber than their elder sibs shows exactly the opposite - they are every bit as smart, well within the ability of the tests to measure.

Dopers, if even Science magazine is not immune to this, fighting ignorance is going to take a LOT longer than we thought. Or feared.
[/QUOTE]

I sense that part of your ire is directed toward the Media giving this study a distribution and trumpeting beyond its significance, given the relatively small difference that was measured.

My gut is that the major traction for this story comes from the opportunity to promote nurture over nature as a cause for IQ differences. This is the spin I have seen put on the study by most of the stories. Were it a study that supported nature (genes) over nurture, with the same near-trivial (albeit statistically significant) difference, I think it would have been left alone as Too Hot to Handle.

It’s not politically incorrect to announce the inferiority of us younger siblings as long as it is in the name of promoting Nurture over Nature, which is a larger Correctness.

As mentioned above I started a thread in GD over this story because I was struck at how small the difference was and therefore am wondering if the study will backfire on the Nurture advocates. If the difference is that small, is the only remaining explanation for differences among siblings Nature?

[John_Mace]

[QUOTE=Chief Pedant]
As mentioned above I started a thread in GD over this story because I was struck at how small the difference was and therefore am wondering if the study will backfire on the Nurture advocates. If the difference is that small, is the only remaining explanation for differences among siblings Nature?
[/QUOTE]

I don’t see any problem talking about difference in intelligence due to genetics. People often freak out if you throw race into it, but there can be no doubt that some people are just born smarter than other people. Sheesh, if intelligence weren’t hereditary, we’d be romping with our cousins, the chimps.

[Colibri]

[QUOTE=Chief Pedant]
As mentioned above I started a thread in GD over this story because I was struck at how small the difference was and therefore am wondering if the study will backfire on the Nurture advocates. If the difference is that small, is the only remaining explanation for differences among siblings Nature?
[/QUOTE]

I’ve responded to this in the GD thread. The 3 point difference is only that attributable to birth order and social rank. The study controlled for other nurture factors that could be important even within families, among them maternal age at birth, sibship size, birth weight, and year of conscription. Of course, there are many other nurture factors that can account for IQ differences between families and between other social groups, including socioeconomic status, education, culture, health, and nutrition.

[brazil84]

[QUOTE=John Mace]
Sheesh, if intelligence weren’t hereditary, we’d be romping with our cousins, the chimps.
[/QUOTE]

A lot of people have been trying to teach apes to talk using sign language. These attempts have generated a good amount of interest and controversy.

[DSeid]

A few years back I read Steven Pinker’s The Blank Slate: The Modern Denial of Human Nature (having previously been impressed by his other books) and was amazed that he wrote a whole book stating what to me seemed like a non-issue. He must have read more of these threads than I had.

His fairly well documented upshot was briefly summarized on page 380-381:

… if you want to be charitable, Genes 40-50 percent, Shared Environment 0-10 percent, Unique Environment 50 percent

Shared Environment refers to family and Unique Environment is everything else that happens to you differently than to your siblings, from birth order to infections to bumping into the bully at the wrong time in school. He of course gives all the caveats: these studies exclude extreme cases like abuse, neglect, and differences between cultural groups. His numbers may or may not be spot on, but most studies bear it up.

IQ may indeed be a “mismeasure of man” but the concept that we have strong biological predispositions to our intellectual potentialities and that how they are manifest depends on culture, our unique experiences, and our families (and likely in that order) seems hard to dispute other than as a matter of political manifesto.

[Voyager]

[QUOTE=Indistinguishable]
Well, in that post, the numbers were meant to refer to the actual, underlying IQ value, rather than that reported by tests.

At any rate, though, certainly the test could distinguish, in some sense, between an IQ of 123 and one of 125, in that the probability distribution on reported values will be different when the underlying value is 123 than when it is 125, such that repeated testing allows us to shrink the size of the confidence interval, eventually removing the overlap between those for 123 and 125. (As before, it seems fair to assume the test is such that, for any particular underlying value, the expected reported value is equal to it).
[/QUOTE]

Just one more thing to add to this - the confidence interval is not the same as measurement error. Whatever the measurement error is for IQ tests, unless there is a reason to believe that the measurement error varies depending on birth order, over a big enough sample it will wash out when comparing two populations.

I’d love to find out if the results change in different societies. The Times article I read said nothing about this.

And an observation: when a random poster blasts the authors of a paper in Science for being statistically naive, the random poster almost certainly doesn’t know what the hell he’s talking about.