Cranial Size and Intelligence Link

[Nereid]

Yep, that's what I was asking about earlier. Thanks, M.
It's shockingly low compared to other areas of science, but I can see how social science studies would be tough (hard to control/account for the variables).

[nitpick]There is a category confusion here; it would seem that intelligence psychometrics can be lumped into 'social sciences' (e.g. with economics and anthropology), but that some of what some psychometricians claim is biological. AFAIK, correlations of 0.5 or lower in biology aren't thought very interesting, and certainly would need to be followed up with further studies to find what (if anything) is giving rise to the correlations. In this sense we could perhaps consider this sub-discipline to have found some interesting results, but to still lack the basics of anything that could be considered part of mainstream biology.[/nitpick]

 

[Moonbear]

[nitpick]There is a category confusion here; it would seem that intelligence psychometrics can be lumped into 'social sciences' (e.g. with economics and anthropology), but that some of what some psychometricians claim is biological. AFAIK, correlations of 0.5 or lower in biology aren't thought very interesting, and certainly would need to be followed up with further studies to find what (if anything) is giving rise to the correlations. In this sense we could perhaps consider this sub-discipline to have found some interesting results, but to still lack the basics of anything that could be considered part of mainstream biology.[/nitpick]

From everything presented on psychometrics in the various threads on this topic, and from my own digging around into the literature, it seems to be quite firmly planted as a subdiscipline of pscyhology. Most psychology departments have sort of a split personality. There are psychologists who focus more on the social science side of things and really aren't interested in the biological mechanisms underlying what they study. The other camp in psychology are the psychobiologists. They focus far more on the biological basis for behavior (behavioral neuroscience has grown out of this field). Psychobiologists are not content with correlations below 0.5 (and would even be cautious about interpreting correlations between 0.5 and 0.75), and interpret such low correlation to mean one of two things: 1) there isn't any real relationship between the two things being studied, it was entirely due to chance, or 2) the study wasn't properly conducted to control for all the variables.

 

[Mandrake]

There is a category confusion here; it would seem that intelligence psychometrics can be lumped into 'social sciences' (e.g. with economics and anthropology)...

It appears to me that your comments here and in prior messages are designed to advance a nihilistic perspective with respect to psychometrics. The problem with your case is that you constantly demonstrate to us that you are unaware of the depth and breadth of the science you criticize. In fact, when issues are explained to you, we find later comments that ignore the prior explanations. I cannot understand your purpose, just as you do not understand the science of psychometrics.

The comparison to economics is as inappropriate and misleading as your inept stamp collection. Economics does not involve laboratory measurements, nor is it a science that deals with human biology. Economics is incapable of displaying differential observations between population groups and between family members. Economics is not genetically determined. The comparison you made is no more appropriate than comparing astronomy to architecture.

... but that some of what some psychometricians claim is biological.

Would you please explain the above comment? My reading of it is that you wish to imply that you hold a different position and that your position is that intelligence is not biological. We have previously discussed the strong links between physiology and intelligence. What does your comment mean in the context of those links? If intelligence is not biological, what is it? Spiritual? Ethereal?

AFAIK, correlations of 0.5 or lower in biology aren't thought very interesting

Correlations are applied as a means of detecting the presence of variables that coexist with other variables. Since I am not a biologist, I will not attempt to speak for that science, but your argument strikes me as an attempt to discredit something, but which is based on your perception and is counter to the understanding that is not challenged by the very competent scientists who have an in-depth understanding of psychometrics. You have not demonstrated that degree of understanding, nor even a good recollection for the material that you have attempted to discuss.

and certainly would need to be followed up with further studies to find what (if anything) is giving rise to the correlations.

A .5 correlation is usually interpreted as one that corresponds to a variance that explains 25% of the variance in the other parameter. Do you dismiss a 25% overlap in two variables? If so, can you explain why? There is another way to look at a .5 correlation. It is half of the maximum possible correlation. In light of your comment about biology, I would like for you to give us a few examples of biological variables that correlate at .5, but which "aren't thought very interesting." Thank you.

 

[CloakNight]

Psychobiologists are not content with correlations below 0.5 (and would even be cautious about interpreting correlations between 0.5 and 0.75), and interpret such low correlation to mean one of two things: 1) there isn't any real relationship between the two things being studied, it was entirely due to chance, or 2) the study wasn't properly conducted to control for all the variables.

I do not know of any scientist that would consider 0.5 a low correlation. 0.5 is generally thought to be a considerably high correlation. Researches on homosexuality as printed in the journals of Science, General Psychiatry, and American Journal of Psychiatry show a genetic correlation of 0.5 for homosexuality. Would you agree then that homosexuality is a choice and predominately environmentally based? Would homosexuality then be "curable"?

 

[humanino]

Welcome CloakNight !

I know many in physics who require much higher correlations. We investigate certainty, not vague facts. We require 99.9999% likelihood before the community accept a discovery. This is of course not possible in biology I guess. Or maybe you should try to search the various topics some guys in this discussion have been debating, and try to make your own opinion about what purpose they try to serve here. I made mine. I know the caution required here. Some people are clever, we must be careful.

 

[bd1976]

Researches on homosexuality as printed in the journals of Science, General Psychiatry, and American Journal of Psychiatry show a genetic correlation of 0.5 for homosexuality. Would you agree then that homosexuality is a choice and predominately environmentally based? Would homosexuality then be "curable"?

Erm.. Dude your logic is sadly lacking. Even if homosexuality is entirely caused by enviromental effects it could be that these effects cause the brain to change as it develops and so the effects are not reversible once the brain has reached maturity.

The problem with this is that its a symptum of a larger problem. Science can not explain how the brain works. Science has very little idea how the brain operates. This has given rise to these "soft sciences" or "social sciences" like psychology. Where you propose an intelligent sopunding idea and tyhen go off and "prove" it with statistics. Often your trying to prove your own clever suggestion so you have a vested interest in the resuts. Look at your own quote. It's from the American Journal of Psychiatry don't you think this group has a vested interest in their being a correlation. Who is going to treat the homo's ... hmmm... prehaps its... Psychiatrist's! Wow there's a coincidence!

 

[Moonbear]

I do not know of any scientist that would consider 0.5 a low correlation. 0.5 is generally thought to be a considerably high correlation. Researches on homosexuality as printed in the journals of Science and American Journal of Psychiatry show a genetic correlation of 0.5 for homosexuality. Would you agree then that homosexuality is a choice and predominately environmentally based? Would homosexuality then be "curable"?

We have to differ on this, r=0.5 is not a high correlation. It's borderline, at least in the field of biology, and I think biologists tend to be more generous than those in other sciences. Further, if you look back through the threads here, you will see that there are some who are claiming r=0.2 is a high correlation, and that is the background for my comments.

I've discussed the topic of homosexuality in other threads here. There is evidence that some of the biology of sexual orientation is indeed not genetically based, nor is it learned behavior or a choice. However, I also don't view that to be something that requires a "cure." And, would you please cite the reference for the Science article(s) you refer to that say a correlation of r=0.5 is a high correlation. The original Science article demonstrating a genetic linkage for homosexuality is does not report correlations, indeed, such an analysis wouldn't fit with the way they collected their data.

A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation
Dean H. Hamer; Stella Hu; Victoria L. Magnuson; Nan Hu; Angela M. L. Pattatucci
Science, Vol. 261, No. 5119. (Jul. 16, 1993), pp. 321-327.

The only other article in Science that I'm aware of on this topic contradicts those earlier findings, though doesn't exclude the possibility of a genetic linkage.

Male Homosexuality: Absence of Linkage to Microsatellite Markers at Xq28
George Rice, Carol Anderson, Neil Risch, George Ebers
Science, Vol 284, Issue 5414, 665-667, 23 April 1999

Both articles are followed by comments in subsequent issues debating the findings, so it's far from an open and shut case.

However, if you'd like to continue to discuss the topic of homosexuality, I suggest taking it to this thread, which is more appropriate to the topic.
https://www.physicsforums.com/showthread.php?t=39163

 

[CloakNight]

Erm.. Dude your logic is sadly lacking. Even if homosexuality is entirely caused by enviromental effects it could be that these effects cause the brain to change as it develops and so the effects are not reversible once the brain has reached maturity.

The problem with this is that its a symptum of a larger problem. Science can not explain how the brain works. Science has very little idea how the brain operates. This has given rise to these "soft sciences" or "social sciences" like psychology. Where you propose an intelligent sopunding idea and tyhen go off and "prove" it with statistics. Often your trying to prove your own clever suggestion so you have a vested interest in the resuts. Look at your own quote. It's from the American Journal of Psychiatry don't you think this group has a vested interest in their being a correlation. Who is going to treat the homo's ... hmmm... prehaps its... Psychiatrist's! Wow there's a coincidence!

As the comments above are completely ignorant to the basics of science, brain anatomy, and a complete insult to anyone having a scientific background, I will ignore this post.

 

[CloakNight]

We have to differ on this, r=0.5 is not a high correlation. It's borderline, at least in the field of biology, and I think biologists.

Whether or not 0.5 would be a high correlation or a mild correlation, it surely wouldn't be nothing. It would show there is a reasonable genetic connection.

Further, if you look back through the threads here, you will see that there are some who are claiming r=0.2 is a high correlation, and that is the background for my comments.

For biology, I could understand why 0.2 would be considered a low correlation but for social sciences I can see why it would be considered more viable.

The original Science article demonstrating a genetic linkage for homosexuality is does not report correlations, indeed, such an analysis wouldn't fit with the way they collected their data.

Bailey and Pillard (1991): occurrence of homosexuality among brothers

52% of identical (monozygotic) twins of homosexual men were likewise homosexual
22% of fraternal (dizygotic) twins were likewise homosexual
11% of adoptive brothers of homosexual men were likewise homosexual

J.M. Bailey and R.C. Pillard, “A genetic study of male sexual orientation,” Archives of General Psychiatry, vol. 48:1089-1096, December 1991.


Bailey and Pillard (1993): occurrence of homosexuality among sisters

48% of identical (monozygotic) twins of homosexual women were likewise homosexual (lesbian)
16% of fraternal (dizygotic) twins were likewise homosexual
6% of adoptive sisters of homosexual women were likewise homosexual

Bailey, J. M. and D. S. Benishay (1993), “Familial Aggregation of Female Sexual Orientation,” American Journal of Psychiatry 150(2): 272-277.

http://www.worldpolicy.org/globalrights/sexorient/twins.html

 

[Moonbear]

Whether or not 0.5 would be a high correlation or a mild correlation, it surely wouldn't be nothing. It would show there is a reasonable genetic connection.

As I said before, it would be something to interpret with caution.

J.M. Bailey and R.C. Pillard, “A genetic study of male sexual orientation,” Archives of General Psychiatry, vol. 48:1089-1096, December 1991.
Bailey, J. M. and D. S. Benishay (1993), “Familial Aggregation of Female Sexual Orientation,” American Journal of Psychiatry 150(2): 272-277.

Unfortunately, neither of those references is available online (both pre-date the online versions of those journals), so I could only read the abstracts. With regard to this thread, what r-value do they claim? Again, I don't really see how one can analyze data on homosexuality using a Pearson's correlation, so I'm really curious how this is relevant. So far, all the analyses I've seen are comparing proportions of populations that are homosexual or heterosexual using chi-squared analyses. Since I can't access the original articles tonight (or anytime soon...our science/medical library is undergoing renovation, so all hardcopies have to be requested for delivery, which is a slow process right now, so I probably won't be requesting articles that aren't directly pertinent to my research), I'd be grateful if you could provide that information for me, and a little context of the related methods.

 

[Mandrake]

We have to differ on this, r=0.5 is not a high correlation. It's borderline, at least in the field of biology, and I think biologists tend to be more generous than those in other sciences. Further, if you look back through the threads here, you will see that there are some who are claiming r=0.2 is a high correlation, and that is the background for my comments.

Do you consider medicine to be a biological science? When a drug company seeks approval for a new drug, it must submit various studies to the government for approval. If a drug is found to correlate at r=.2 to a side effect that causes permanent disability or death, will the drug be approved? At what value of r would the license be granted? The same question can be asked with respect to drugs that might be given to pregnant women. If r=.2 for deformed babies or death to the fetus, would the drug be allowed for use with pregnant women?

If you were considering an elective operation and knew that the correlation between the procedure and a debilitating outcome was .2, would you have the operation? If not, what value of r would you consider to be acceptable?

 

[humanino]

This is a ridiculous argument ! There are some sides effects, always. If the drug compagnies had the same requirements as in physics, there would be none.

Of course, there would also be no drug passing so high requirements. This is only due to market considerations. If they had long enough time (say over decades) they would be able to produce such medicines.

 

[Moonbear]

Do you consider medicine to be a biological science? When a drug company seeks approval for a new drug, it must submit various studies to the government for approval. If a drug is found to correlate at r=.2 to a side effect that causes permanent disability or death, will the drug be approved? At what value of r would the license be granted? The same question can be asked with respect to drugs that might be given to pregnant women. If r=.2 for deformed babies or death to the fetus, would the drug be allowed for use with pregnant women?

If you were considering an elective operation and knew that the correlation between the procedure and a debilitating outcome was .2, would you have the operation? If not, what value of r would you consider to be acceptable?

In the examples you cite, the data wouldn't be analyzed that way. A Pearson's correlation (r) is the wrong statistic to use. So, if a company seeking drug approval handed a report to FDA that included such a statistic, no, the drug would not be approved because FDA would tell them their analysis was flawed. Drug trials would not include correlations or even post-hoc analyses; those are very frowned upon by FDA. Severe side effects that required people drop out of the study or led to serious health problems would either be reported as a proportion of the subjects reporting the side effects or using a survival analysis. Using a Pearson's correlation requires comparing two variables with a normal distribution and similar standard deviations. The closer r is to 0, the more scattering there is of the values from a linear relationship.

 

[Mandrake]

This is a ridiculous argument ! There are some sides effects, always. If the drug compagnies had the same requirements as in physics, there would be none.

I didn't make any argument. I asked a few questions. We all know that drugs have side effects and are sometimes licensed with side effects that can be serious. The question is whether a .2 correlation is insignificant with respect to biology. Your answer is apparently a resounding YES. But the question I raised is at what correlation is the risk of a serious complication accepted as small enough to allow. I seriously doubt that a drug with life threatening side effects in the r = .2 range would be licensed. If that is true, we can conclude that this example of biology recognizes small correlations as very important.

 

[Mandrake]

In the examples you cite, the data wouldn't be analyzed that way. A Pearson's correlation (r) is the wrong statistic to use.

If you can produce a scatter diagram with the data, you can determine a correlation coefficient. I am not claiming anything about the licensing prodedures of the FDA. The simple question is whether a drug would be licensed if it had that kind of correlation. I asked a similar question with respect to whether or not readers here would undergo elective surgery, if they believed that the correlation between that operation and severe impairment could be represented by a correlation coefficient of .2.

 

[humanino]

Your answer is apparently a resounding YES.

Nope. Never said that. I said, with regards to lethality, a widespread product cannot take such a high risk. 1% of consumer dying would be far above acceptable level for instance. However, 1% of likelihood for a scientific result, does that look acceptable to you ?

 

[Moonbear]

If you can produce a scatter diagram with the data, you can determine a correlation coefficient. I am not claiming anything about the licensing prodedures of the FDA. The simple question is whether a drug would be licensed if it had that kind of correlation. I asked a similar question with respect to whether or not readers here would undergo elective surgery, if they believed that the correlation between that operation and severe impairment could be represented by a correlation coefficient of .2.

My point is you can't produce a scatter diagram with the type of data you suggested. Instead, you'd have something along the lines of drug vs placebo or new drug vs currently approved drug, and for each, you'd have incidence of reported side effect as your dependent variable. So you're just creating an argument with no validity because it doesn't fit with the way real data are collected or analyzed. If you're thinking of this differently than that, please demonstrate the type of data you're envisioning would be collected for such an analysis...feel free to make up a fictitious data set if it helps illustrate the point.

 

[Mandrake]

My point is you can't produce a scatter diagram with the type of data you suggested.

Yes, I agree. I understand your point. Correlations relate variables. I picked poor examples, since I was suggesting a binary outcome, such as survival or death. In order for a correlation to be used with respect to a drug or a medical procedure, there must be two variables. In the context of my comments, one of the variables would have to be an outcome. When the outcome is a parameter that is measured over a range, it is unlikely that a life and death situation exists. I presume outcomes that would apply to these categories may be things such as vision acuity, lung capacity, blood pressure, IQ, hearing acuity, physical strength, etc. All of these are measurable over a range.