The chief complaint seems to be that they only found statistical significance on one measure for one subpopulation (boys), and other measures were not significant (and while the correlation for girls was not statistically significant, it was leaning the opposite direction!).
Sure, maybe there's a correlation purely centered around boy's non-verbal IQ scores, but it smells a lot like a "if you look for enough correlations you'll eventually find one".
Interesting. Is it odd that the IQ scores were over 100?
For example, population IQ is supposed to be 100. So a score of 105 for boys with a 5 point drop would give us the expected result of average intelligence, right?
>Between 2008 and 2011, the Maternal-Infant Research on Environmental Chemicals (MIREC) program recruited 2001 pregnant women from 10 cities across Canada. Women who could communicate in English or French, were older than 18 years, and were within the first 14 weeks of pregnancy were recruited from prenatal clinics. Participants were not recruited if there was a known fetal abnormality, if they had any medical complications, or if there was illicit drug use during pregnancy. Additional details are in the cohort profile description.
Seems like that would filter out the lower end of the bell curve, especially regarding drug use.
This could just a) be Flynn effect in action (although I would think that would take longer) [0], or b) there are other factors in the sample group (Canadians) that shift them slightly higher in baseline IQ (nutrition? educational exposure?).
Insert the obligatory USAF General Jack T. Ripper quote, about the Soviets fluoridating our water supplies, to pollute the "precious bodily fluids" of American men. [ https://en.wikipedia.org/wiki/Dr._Strangelove#Plot ]
(No, I am not a public health professional, to know if their study's design or other research would rule out paternal exposure to fluorine as a cause. However, I have a very strong impression that both public opinion and most medical professionals are strongly sexist about problems with pregnancy and young children - "anything wrong is the mother's fault".)
If flouride indeed both strengthens teeth and bones and lowers IQ, it becomes even more challenging to pick an optimum level.
I think that the more complex a question is, the more important it is for the answers to be decentralized so that we can experiment with many of them. If fluoride does have significant negative as well as positive effects, that's an argument toward removing it from water supplies and making it a choice. Reasonable people could decide that they prefer weaker bones than minds, or visa versa.
Those are supposed to have lower fluorine than tap water. According to the CDC, babies who only drink formula with tap water can develop dental fluorosis, faint white lines on the teeth.[1].
From your link it mentions to use water “without any fluoride added after purification treatment. The U.S. Food and Drug Administration (FDA) requires the label to indicate when fluoride is added.” The water I’m referring to is exactly the kind of water the CDC recommends against using, yet that is not at all obvious from the label. IIRC it is sold right next to the infant formula implying it should be used.
Again, what purpose does it serve? Babies and toddlers don’t have their adult teeth so it is irrelevant for dental health at that age.
10 years ago I chose to have my kids in a community that does not fluoridate the water because there has LONG been an association with IQ and ingesting fluoride.
But, MOST insanely, fluoride is by all account a medicine, we are one of the ONLY countries in the world that medicates our water supply. Just think about it, why do we medicate our ENTIRE water supply?
There is something terrible behind the fluoridation of the American water supply, I have no idea what but I do know that as a scientist what we are doing makes no sense and is VASTLY more harmful then beneficial.
The wording in the summary could have been done better. Read casually, it comes across as suggesting causation instead of correlation:
Findings -- In this prospective birth cohort study, fluoride exposure during pregnancy was associated with lower IQ scores in children aged 3 to 4 years.
Meaning -- Fluoride exposure during pregnancy may be associated with adverse effects on child intellectual development, indicating the possible need to reduce fluoride intake during pregnancy.
IQ is the most strongly supported thing in the field of social science/psychology. Way more strongly supported than many of the concepts being used to steer government policy
The irony being that tons of social science academics desperately want to prove IQ is bunk and become famous for it, but their failures just keep proving it's legitimacy. If only they tried so hard to disprove their own pet theories
IQ as a measurement of general intelligence has been repeatedly called into question and deligitimized with strong evidence by the fields of psychology and sociology for 30+ years for myriad reasons.
In fact, most of the continuing proponents for IQ testing take the stance of "We don't have anything better, so we will use it even if it's deeply flawed." This viewpoint is so prevalent that a majority of studies on the subject in the last 10-15 years are skewed towards evaluating alternative testing methods.
Here's a small sample of studies showing the different reasons IQ tests fail to measure intelligence:
very low IQ scores correlate with ordinary measures of mental performance. Above 100, they're randomly correlated with generic extrinsic measures of performance, and have little test-retest consistency.
You can differ as much in your test-retest score as would be the gap between mental retardation and "normal".
Above 100, they're mostly a measure of proficiency at taking written tests.
In any case, there is no theory of what IQ measures other than by assertion that it measures "intelligence", so there's nothing actually to be said about it.
It's a means of extracting apparent patterns in some test answers; there is no scientific theory of what those patterns mean.
Extracting apparent patterns in [test answers] is a cognitively difficult task, and is thus a reasonable metric of performing cognitively difficult tasks.
Given that this is what we are attempting to measure, it seems completely fine. Pointing out flaws in the test (lack of generality, non-deterministic behavior) is not actually a counter-argument so long as the test correlates with at least some outcomes that we care about.
No no, i mean the psychometrist is the person superstitiously using the fact that answers to their choice of questions correlate, as some measure of something.
The claim that IQ tests are "cognitively difficult" is either trivial or unevidenced. Its trivial in the sense that most tasks are "cognitively difficult", that doesnt make them valid measures of cognitive difficulty. It is unevidenced in the sense that there is no theory of what "cognitive difficulty" means that can be tested.
My apologies, but IQ tests really are actually pseudoscience. They're a product of a discipline which superstitiously uses GUI-statistical tooling without understanding anything abotu the scientific method, nor the statistical metrics that these tools report.
An animal, and its intelligence, is a complex chaotic system whose "cognitition" or "intelligence" is by no means measured by an IQ test. And such a claim is prima fascie ridiculous from any actual biological (ie., theory-building, scientific) study of intelligence.
I would say that the particular importance of the measurement is far less relevant than the repeatability of the measurement. In that regard, because IQ is very repeatable in the mid-range, population effects measured by IQ should be considered as evidence of some effect on the neurological system.
Even if IQ is meaningless, this result is still evidence of neurological harm.
There’s no replication crisis in psychometry. It’s the highest quality area of psychological research, at least with respect to reproducibility. While there’s room for debate as to what exactly it is that’s being measured, there is none for whether something meaningful at all is being measured.
IQ measurements have strong predictive power too for various outcomes, such as educational attainment.
A civilization reduction of IQ by nearly 1/3 sigma is absolutely cause for concern.
IQ only has predictive power at very low scores; above 100 it randomly correlates with, eg., wealth and various other extrinsic objective measures.
The only cases where "success" is measured by the profession are circluar, ie., its often claimed Drs/lawyers etc have high IQs, but necessarily so, since they're all filtered based on IQ tests.
Psychometry has nothing to replicate, because there are no psychometric theories. It is simply a field which finds patterns in exams it makes up, based on no testable theories, and asserts that these patterns have "some meaning". There isnt anything here to replicate.
For some reason some people just really hate the idea that intelligence is something that can be measured with some accuracy. You're just repeating their discredited arguments that have been reliably debunked for decades now.
In reality, intelligence is the single most selected for human trait and it correlates with, to a greater or lesser extent, being better at basically everything. In other words, it has many phenotypic consequences. That includes some pretty surprising things, like semen quality[1] and height[2]. And then there's the obvious stuff like higher IQ correlating with better performance in school and work[3]. It also correlates with higher income and lower criminality, but those effect sizes are smaller.
The IQ test is a test, people good at taking tests are good at taking tests. This doesnt rise to the level of a theory of intelligence, nor evidence that IQ measures it.
A vast amount of "mere statistical" research is pseudoscience; entire fields. It requires a lot of experience in hard scientific methodology, and an actual education in statistics. A lot of experimental sciences attract people interested in the experiments who just plug data into models and report the results.
The vast majority of such "research" is pseudoscience, and it's one massive house of cards. Most "heritability" research, population genetics research, psychometrics, psychology, nutrition, etc. is pseudoscience.
The whole type of statistics that has basically been invented by the social sciences is the basis for massive amounts of pseudoscience. Factor analysis, propensity scores, correlation coefs, etc. -- it's just an analysis of correlation.
Such is the poverty of thinking in these "social sciecnes" that they arent trained enough to realise that a model of correlations in effects isnt a model of their causes, not even nearly so. And this is esp. sevre in the case of complex systems like humans and animals.
All of the methods of IQ research are simple models of correlations in quiz answers. They do not rise to the level of a theory of anything, and their use is routinely circular and unethical.
You're just repeating yourself and then making hand-waving attacks on scientists. This is the tier of "argument" we hear from anti-vaxxers. Surely you can do better than vague ad hominems implying either incompetence or malfeasance? Such claims require evidence.
Yes there is a replicability crisis in much of the social sciences. Yes cargo cult science[1] has been a real problem and continues to be. Nevertheless there isn't a replication problem for psychometry. Countless researchers have dedicated their careers to showing that there is, and yet they have all failed to do so. I agree though there is room for improvement. IQ is only a model and we're measuring a proxy for intelligence, not intelligence itself. Still, it's a pretty good proxy, just as grip strength is a pretty good proxy for overall physical strength.
There is also high quality replicable research in all those fields you disparage. For example, generally speaking, metabolic ward nutrition research is of high quality.
There can't be a "replication" problem for IQ. There is no theory of intelligence provided, there are no independent valid and reliable measures of it, and there has been no work to show IQ measures it.
The argument is just, "I rekon intelligence has something to do with quizes like this, and look, there are correlations in people's answers!"
That's the premise of the entire field. It doesnt have a theory of intelligence, and any even plausible scientifically-grounded theory of intelligence would pretty clearly invalidate IQ as a measure of it.
HN isnt a place to give a lecture course on statistics, causal modelling and the scientific method. But the vast majority of people I'm aware of with serious work in those areas, regard this entire field as pseudoscience. It is only researchers within this field who believe otherwise, and they arent professionals.
> There can't be a "replication" problem for IQ. There is no theory of intelligence provided, there are no independent valid and reliable measures of it, and there has been no work to show IQ measures it.
The argument is just, "I rekon intelligence has something to do with quizes like this, and look, there are correlations in people's answers!"
Is your claim now that there is no such thing as intelligence? If we accept that premise then sure the whole field is bunk, because you can't measure something that doesn't exist. However I consider such a claim as ludicrous as saying that there is no such thing as strength, so if that's your position then I don't think I have much to learn from you.
Meanwhile, the g factor[1] is a theory of intelligence that basically says people who are good at one kind of cognitive task will also be good at other kinds of cognitive tasks. Is that entirely satisfactory? I've already said there's room for improvement. Nevertheless we have to start somewhere, and given the complexity of the array of phenotypes we associate with intelligence the g factor isn't a bad start.
> any even plausible scientifically-grounded theory of intelligence would pretty clearly invalidate IQ as a measure of it.
This sounds like an easy claim to support. Since you are enthusiastically anti-psychometry I assume you've done the research. What do you mean by "plausible scientifically grounded?" Would you please give a supporting example?
> HN isnt a place to give a lecture course on statistics, causal modelling and the scientific method. But the vast majority of people I'm aware of with serious work in those areas, regard this entire field as pseudoscience. It is only researchers within this field who believe otherwise, and they arent professionals.
HN is a place for satisfying intellectual curiosity. You would be contributing to the site's reason for existing by giving an abbreviated lecture actually showing that you have a point rather than just appealing to unknown authorities.
If you're saying that lawyers and PhDs all have to score high on what's literally an IQ test, then I don't think that is true. You can become both without ever doing an IQ test, and as such there can be no filtering -- are those even routinely administered?
However, to succeed at higher education (and to get into it), especially written tests, you need to be good at some stuff that also means you'll be decent at an IQ test. That means they have some value, though I tend to agree that it means very little overall.
Of course it is, but it's not "literally an IQ test" in that the result is not an IQ. Universities don't require an IQ above 105 to apply, they require good grades.
Apparently in other places, doctors and lawyers literally take an IQ test, which is bizarre.
Or maybe the original poster has an unusually broad understanding of what's an IQ test, in that pretty much any (written?) examination qualifies. Which would transform his thesis from "IQs are a sham" to "any evaluation of specific aptitude and knowledge is a sham".
Yes, I believe that's essentially his thesis, at least with respect to aptitude, based on my discussion with him in a sister thread.
He's apparently referring to the MCAT and LSAT, which serve as entrance examinations for medical and law schools respectively.
Similarly the SAT, which is the undergraduate entrance examination used by many schools, is a very good predictor for score on an actual IQ test. So much so that one can conflate the two without really being very wrong.
