Author Topic: Sex differences in brain size and general intelligence  (Read 319 times)

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Online Desert Fox

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Offline elena

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Re: Sex differences in brain size and general intelligence
« Reply #1 on: May 10, 2017, 11:31:10 AM »
I'm not in the field, but if someone more knowledgeable could explain what results of differences in fraction of standard deviation could possibly mean (looking at table 5), I'm all ears.

Offline Drunken Idaho

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Re: Sex differences in brain size and general intelligence
« Reply #2 on: May 10, 2017, 01:03:34 PM »
I'm not in the field, but if someone more knowledgeable could explain what results of differences in fraction of standard deviation could possibly mean (looking at table 5), I'm all ears.

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Offline HanEyeAm

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Re: Sex differences in brain size and general intelligence
« Reply #3 on: May 16, 2017, 08:06:43 AM »
I'm not in the field, but if someone more knowledgeable could explain what results of differences in fraction of standard deviation could possibly mean (looking at table 5), I'm all ears.
1/4 of a standard deviation is z=.25, a pretty small difference. Assuming the overall mean IQ is 100 with equal numbers of male and female participants, the group mean for males will be 102 and for females 98. Both of those are really close to average and are really close to each other, begging the question of whether it's a meaningful difference.

I didn't have time to look at this article in depth, but there certainly have been a lot of studies about brain volume and intelligence (and gender for that matter) so I really think the results of this study need to be considered Within the whole of the literature base.

Offline The Latinist

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Re: Sex differences in brain size and general intelligence
« Reply #4 on: May 16, 2017, 09:17:06 AM »
Han, isn't σ of IQ tests generally 15?
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Offline Ah.hell

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Re: Sex differences in brain size and general intelligence
« Reply #5 on: May 16, 2017, 09:42:40 AM »
IQ is standardize with the mean at 100 and standard deviation at 15.  Which is why IQs have been increasing world wide without being widely reported and highly suggestive of a culture bias.   Which would be all you need to explain any difference in men and women.   While we are raised in the same culture, its norms are significantly different for men and women. 

Offline HanEyeAm

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Re: Sex differences in brain size and general intelligence
« Reply #6 on: May 16, 2017, 09:49:17 AM »
Han, isn't σ of IQ tests generally 15?
Yep. Strange, isn't it? The distance between IQ scores for a particular range of z-scores varies depending on where you start in the range of possible scores. It must be a quirk of interval measurements. Google a standard score conversion table and check it out.

Online superdave

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Re: Sex differences in brain size and general intelligence
« Reply #7 on: May 16, 2017, 09:59:22 AM »
Han, isn't σ of IQ tests generally 15?

The 0.25 is the difference between the two z scores.  The standard deviation between each group though were both about 0.88, more than 3 times the difference between the groups.  So there is significant overlap.  It would have been nice for the paper to actually show us the histograms for their g value. 

In general, the paper seems to hold together, though its hard to actually glean much meaningful info.  Male brains are slightly larger than female brains, and this seems to correlate with slightly higher IQs on average.  The difference held up across several tests, so I would believe it is real.  However, the effect size is probably only somewhat greater that the accuracy of the tests themselves, especially if there is any bias within those tests, and is almost certainly not significant difference for every day tasks.  There was much more variety within the groups than between them. 

bottom line, the conclusion seems plausible but not very meaningful.


A lesson I taught in my stats class this year was to consider something like Astrological sign.  You could measure the sign of everyone in the school, get great statistics, but ultimately not prove anything interesting.
« Last Edit: May 16, 2017, 10:02:39 AM by superdave »

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Re: Sex differences in brain size and general intelligence
« Reply #8 on: May 16, 2017, 12:57:02 PM »
Ummmm....   Isn't it brain weight to body weight ratio that matters more?  Or is that by species?
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Offline HanEyeAm

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Re: Sex differences in brain size and general intelligence
« Reply #9 on: May 16, 2017, 01:11:03 PM »
I haven't had time to look at the article but regarding gender differences, it may be that sampling methods resulted in unrepresentative samples. That is, despite all attempts, the women in the sample, on average, just weren't as smart as the population of women ( or the men were a bit smarter than the average).

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Offline Ah.hell

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Re: Sex differences in brain size and general intelligence
« Reply #10 on: May 16, 2017, 01:14:39 PM »
Ummmm....   Isn't it brain weight to body weight ratio that matters more?  Or is that by species?
I thought the same thing but the article claims:
Quote
Males displayed higher scores on most of the brain characteristics, even after correcting for body size....
So, should have been corrected for.

Offline Johnny Slick

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Re: Sex differences in brain size and general intelligence
« Reply #11 on: May 16, 2017, 01:31:44 PM »
OH SO FAT PEOPLE ARE STUPIDER THAN THIN PEOPLE NOW I AM ENJOYING WATCHING YOUR HYPOCRISY
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Offline Drunken Idaho

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Re: Sex differences in brain size and general intelligence
« Reply #12 on: May 16, 2017, 03:37:04 PM »
OH SO FAT PEOPLE ARE STUPIDER THAN THIN PEOPLE NOW I AM ENJOYING WATCHING YOUR HYPOCRISY

 :laugh:
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