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Comment by a_bonobo | Hacker News Reader

Title using 'very large' does not come from the article, which gives a more subtle image:

>Sex Differences in the Adult Human Brain: Evidence from 5216 UK Biobank Participants

>Males had higher raw volumes, raw surface areas, and white matter fractional anisotropy; females had higher raw cortical thickness and higher white matter tract complexity. There was considerable distributional overlap between the sexes.

Personally I wouldn't call the difference between a mean of 1115.76 with an standard deviation of 89.68 and a mean of 1233.58 with an SD of 98.31 very large (all in cm^3)

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Please note that 'very large' was indeed quoted directly from the paper.

"The average difference for the 14 subcortical volumes was d = −0.70. A set of Bayesian t-tests (see Supplemental Materials and Table 1) confirmed that the mean sex differences were very large, with extremely strong evidence in favor of the hypothesis that males differed from females "on every overall and subcortical volume."

You add that in your personal opinion the difference is 'not very large'. What should be the magnitude of the numbers below to fall into the 'large' category in your assessment?

Quote: "...total brain volume translates to 92.1% of males being above the female mean and an 84% chance that a randomly-chosen male will have a large brain volume than a randomly chosen female" That's pretty significant in terms of means.

Cherry-picking a phrase and making it the title is a form of editorializing, which breaks the HN guidelines.

https://news.ycombinator.com/newsguidelines.html

When the topic is divisive, doing this is particularly bad. It can easily ruin the thread for discussion. If you want to say what you think is important about an article, please do so in a comment. Then your view is on a level playing field with everyone else's.

Yes, it's a superficially inflammatory title.

This paragraph from the discussion is interesting:

> An additional hypothesis—one that is not incompatible with the hypothesis that some of the sex differences seen here are a proximate cause of behavioral differences—is that brain structural differences might sometimes be the result of compensatory mechanisms for differences in sex-specific hormones, and might thus act to reduce behavioral sex differences that would otherwise have been present (De Vries 2004; McCarthy and Arnold 2011). This perspective may in part explain an apparent paradox in human sex difference research: that the (raw) effect sizes found for brain measures such as volume and surface area are so large, whereas most behavioral sex differences are so small (Hyde 2014). Our descriptive results do not directly speak to any causal mechanisms, but it should be borne in mind that they are compatible with these multiple interpretations.

The effect size is quite large. From the paper,

The differences were substantial: in some cases, such as total brain volume, more than a standard deviation. The effect size of d = −1.41 for total brain volume (Table 1) translates to 92.1% of males being above the female mean, and an 84.1% chance that a randomly-chosen male will have a larger total brain volume than a randomly-chosen female.

This resolves to something like 70% males have larger brains than 70% females.

Actually, the paper states:

> The differences were substantial: in some cases, such as total brain volume, more than a standard deviation. The effect size of d = −1.41 for total brain volume (Table 1) translates to 92.1% of males being above the female mean, and an 84.1% chance that a randomly-chosen male will have a larger total brain volume than a randomly-chosen female.

The height of the average male (178cm) is more than one standard deviation (8.9cm) above the height of the average female (165.1cm).

I don't really know if we should be surprised that the differences between male and female brain volumes are also statistically significant and larger than one standard deviation.

Not only that, there was significant overlap in the distributions.

TFA measures a lot more than mere total brain volume.

Yeah, and let's just pretend that your implied argument, that looking at the other values measured finds that they, in toto, mean the brains are equal. Of course that's very far from the truth.

It's funny: your statement is perfectly true, and yet gives completely wrong information ... you ever thought about taking up politics ?

But no worries: the study did mention the forbidden metric of death : cognitive tests.

First, an important note: the cognitive tests were specifically chosen to be tests where the mean between men and women would be the same, this is not a coincidence. It is known that there are tests where the mean is not the same between males and females. For example, males have a slight advantage in 3d reasoning skills and females have somewhat better temporal analysis skills ("males aim, females plan").

It shows the same as all others, by the way. Male brains are more experimental : more variable in nearly every way. The dumbest human alive is very likely male, and so is the smartest.

Let's face facts here: the very basis for tolerance is, flat out, totally, and completely wrong. There are in fact sex differences, including in the brain and resulting ability. (worse: there are race differences too. aiaiai)

Whether that means we should or should not practice tolerance is, of course, an unrelated question. But we should be able to answer it without falsifying and denying scientific results.

There, I think every sacred egg, left and right, racist and tolerant, has been thoroughly stomped on. Can we now have an adult discussion ?

Arguing like this, crossing into personal nastiness while slinging rhetoric like weapons, will get you banned on HN, regardless of how right or wrong your or anyone else's views are. Please don't post like this again.

https://news.ycombinator.com/newsguidelines.html

It's funny: your post comes across like you're arguing against me, yet I actually agree with most of what you wrote.

I think we should be able to acknowledge and accept our differences but also be tolerant of them.

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