AnthonyC comments on 2012 Survey Results - Less Wrong

80 Post author: Yvain 07 December 2012 09:04PM

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Comment author: Kindly 29 November 2012 10:14:33PM 3 points [-]

Fishing for correlations is a statistically dubious practice, but also fun. Some interesting ones (none were very high, except e.g. Father Age and Mother Age):

  • IQ and Hours Writing have correlation 0.26 (75 degrees), which is the only interesting IQ correlation.
  • Siblings and Older siblings have correlation 0.48 (61 degrees), which isn't too surprising , but makes me wonder: do we expect this correlation to be 0.5 in general?
  • Most of the Big Five answers are slightly correlated (around +/-0.25, or 90+/-15 degrees) with each other, but not with anything else except the Autism Score. Shouldn't well-designed personality traits be orthogonal, ideally?
  • CFAR question 7 (guess of height of redwood) was negatively correlated with Height (-0.23, or 103 degrees). No notable correlation with the random number, though.
Comment author: AnthonyC 14 December 2012 04:18:38PM 1 point [-]

"Siblings and Older siblings have correlation 0.48 (61 degrees), which isn't too surprising , but makes me wonder: do we expect this correlation to be 0.5 in general?"

In every sibling relationship, there is one older and one younger sibling, so half of all siblings are older siblings - a line with slope 0.5.

Comment author: [deleted] 14 December 2012 09:08:27PM *  0 points [-]

A correlation coefficient is not a slope. (A slope changes if you multiply one of the variables by a constant, whereas a correlation doesn't.)

EDIT: I think the slope is the correlation times the standard deviation of y divided by the standard deviation of x.

Comment author: gwern 14 December 2012 08:04:18PM 0 points [-]

How would twins reply to these questions?

Comment author: thomblake 14 December 2012 08:11:26PM 0 points [-]

All the twins I've known have regarded the first-born as "older" (and one has been first-born).

Comment author: [deleted] 14 December 2012 09:09:04PM 1 point [-]

In Italy traditionally it's the other way round. (Don't ask me why.)

Comment author: thomblake 14 December 2012 09:36:56PM 1 point [-]

So apparently, according to tradition the twin that is conceived first is believed to be born last, and there are folk explanations like "The first conceived attaches to the uterus first, so is more firmly stuck". And so the later-born is considered oldest due to having been conceived first, even though that is not even a thing that can happen in the case of identical twins.

Still tracking down a decent history of the phenomenon, but it's an interesting start.

Comment author: thomblake 14 December 2012 09:18:58PM 0 points [-]

That sounds very counterintuitive. Do you have a citation? I can't find information online.

Comment author: [deleted] 14 December 2012 09:26:58PM *  2 points [-]

It's something I heard from my uncles (a pair of twins) and their mother. I can find stuff online, but it's in Italian. Googling for gemello più vecchio (Italian for ‘older twin’) does turn up relevant stuff, so it's not something my grandma made up. EDIT: apparently there was a myth about the first to be conceived is the last to be born (which for identical twins is Not Even Wrong). Someone answered on Google Answers, "if you went in a phone booth with a friend, the first of you to get in would be the last to come out, wouldn't she?"

Comment author: thomblake 14 December 2012 09:30:48PM *  0 points [-]

My Italian should be good enough for that. Grazie!