His stated point is about telling things that everybody is supposed to know.
If you have an SD of 35 for an average of 1362 you have no idea about whether the last digit should be a 2. That means either you do state an error interval or you round to 1360.
European gained a lot of bodymass over the last 100 years due to better nutrition. The claim that it’s static at 4 digit in a way where you could use 30 year old data to describes todays situation, gives the impression that human brainsize is something with is relatively fixed.
The difference in brain size between Africans and European in brainsize in that study is roughly the difference in height between todays Europeans and Europeans 100 years ago.
Given that background taking a three decades old average from one sample population and claiming that it’s with 4 digits accuracy the average that exist today is wrong.
His stated point is about telling things that everybody is supposed to know.
No, that was absolutely not his point. I don’t understand how you could have come away thinking that- literally the entire next paragraph directly stated the exact opposite:
Graduate students in anthropology generally don’t know those facts about average brain volume in different populations. Some of those students stumbled onto claims about such differences and emailed a physical anthropologist I know, asking if those differences really exist. He tells them ‘yep’ – I’m not sure what happens next. Most likely they keep their mouths shut. Ain’t it great, living in a free country?
More generally, that was not a tightly reasoned book/paper about brainsize. That line was a throwaway point in support of a minor example (“For example, average brain size is not the same in all human populations”) on a short blog post. Arguments about the number of significant figures presented, when you don’t even disagree about the overall example or the conclusion, are about as good an example of bad disagreement as I can imagine.
No, that was absolutely not his point. I don’t understand how you could have come away thinking that- literally the entire next paragraph directly stated the exact opposite:
I don’t think that the following classes are the same: (1) Facts everyone should know. (2) Facts everyone knows.
I think the author claims that this is a (1) fact but not a (2) fact.
(a) Everybody knew that different ethnicities had different brain sizes
(b) It was an uncomfortable fact, so nobody talked about it
(c) Now nobody knows that different ethnicities have different brain sizes
If you have an SD of 35 for an average of 1362 you have no idea about whether the last digit should be a 2. That means either you do state an error interval or you round to 1360.
If individual datapoints have an SD of 35, and you have 20000 datapoints, then the SD of studies like this is 35/sqrt(20000)≈0.24. So giving a one’s digit for the average is perfectly reasonable.
According to the paper the total mean brain size for males is 1,427 while for females it’s 1,272. Given around half women and half men the SD per point should be higher than 35.
His stated point is about telling things that everybody is supposed to know.
If you have an SD of 35 for an average of 1362 you have no idea about whether the last digit should be a 2. That means either you do state an error interval or you round to 1360.
Human height changed quite a bit over the last century. http://www.voxeu.org/article/reaching-new-heights-how-have-europeans-grown-so-tall . Taking data about human brainsize with 4 digit accuracy and assuming that it hasn’t changed over the last 30 years is wrong.
European gained a lot of bodymass over the last 100 years due to better nutrition. The claim that it’s static at 4 digit in a way where you could use 30 year old data to describes todays situation, gives the impression that human brainsize is something with is relatively fixed.
The difference in brain size between Africans and European in brainsize in that study is roughly the difference in height between todays Europeans and Europeans 100 years ago.
Given that background taking a three decades old average from one sample population and claiming that it’s with 4 digits accuracy the average that exist today is wrong.
No, that was absolutely not his point. I don’t understand how you could have come away thinking that- literally the entire next paragraph directly stated the exact opposite:
More generally, that was not a tightly reasoned book/paper about brainsize. That line was a throwaway point in support of a minor example (“For example, average brain size is not the same in all human populations”) on a short blog post. Arguments about the number of significant figures presented, when you don’t even disagree about the overall example or the conclusion, are about as good an example of bad disagreement as I can imagine.
I don’t think that the following classes are the same:
(1) Facts everyone should know.
(2) Facts everyone knows.
I think the author claims that this is a (1) fact but not a (2) fact.
His claim was:
(a) Everybody knew that different ethnicities had different brain sizes (b) It was an uncomfortable fact, so nobody talked about it (c) Now nobody knows that different ethnicities have different brain sizes
If individual datapoints have an SD of 35, and you have 20000 datapoints, then the SD of studies like this is 35/sqrt(20000)≈0.24. So giving a one’s digit for the average is perfectly reasonable.
According to the paper the total mean brain size for males is 1,427 while for females it’s 1,272. Given around half women and half men the SD per point should be higher than 35.
(Assuming the sample is unbiased.)