Disruption-clipped left-tail effect basically. Given 2-child norm, you either have older or younger sibling. If you’re 20 when you join, an older 23 year old sibling is likely to get on, but a younger 17 year old is not...snared by Snapchat/instagram instead
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Basically we’re seeing effect of social media tech disruption cycle being about the same as typical sibling age gaps. That’s my working hypothesis. This is an artifact of tech cycles and early adopters if anything tending young, not a true birth-order effect.
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I’ll add links to all 4 polls here. Do not RT them, to avoid cross-contamination. Feel free to run the same poll and add your poll to this thread. If you do, please mention your age (assuming your followers ages will correlate a bit with yours) and your general tweeting themes.
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Here’s mine: tech consultant in 40s
Quote Tweet
Poll: What’s your birth order among siblings (include step-siblings you grew up with)
Show this poll
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Here’s Brian’s poll, physicist in 30s
Quote Tweet
Poll: What is your birth order among your siblings (include step-siblings you grew up with)
Show this poll
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And here’s Visa’s, late 20s (?) marketer in Singapore
Quote Tweet
Poll: What’s your birth order among siblings (include step-siblings you grew up with)
Show this poll
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The tech cycles explanation is not entirely convincing. Scott Alexander of also found the effect, he’s a psychologist/rationalist community blogger and polled people at meetups etc, not twitter slatestarcodex.com/2018/01/08/fig
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Scott thinks it might be due to STEM effects...older siblings more likely to go into STEM fields. If so, it might also contribute to twitter case. STEMmies being overrepresented here in general and probably specifically for 2 of 4 of us (Brian and me)
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I do know indirectly via other polls that my followers are strongly STEM biased. So if that’s part of the explanation, it would apply at least in my case.
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Note: the bigger the sibling-set, the stronger the left-tail clipping effect. If you have many siblings, like Brian, gap between oldest and youngest will be bigger. If you are oldest/middle and joined Twitter at ~22, almost no chance that 5+ years younger sibling will be here.
And finally, to the extent twitter attracts a “type” independent of age, even in steady state there’s going to be tail clipping. If you’re 20 and joined today, older sibling is probably also on here, but younger one likely will not join. So it’s not a 1-time early adopter effect
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A reasonable null hypothesis is that there's no birth-order effect, and it's all artifact of tech cycles. pointed me to Judith Harris' Nurture Assumption as key ref here. I haven't read it. Just noting it here in case anyone wants to dig.
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Of course, gotta also note usual caveats: absence of evidence is not evidence of evidence, can't prove a negative, replication crisis in social psych etc., but the unfoundedness of several specific birth-order effect hypotheses does call the general idea into question as well.
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Above my statistics pay grade, but clearly if you do a convolution of a moving unstable distribution like a series of intersecting adoption curves spaced 2-5 years apart, with a symmetric one like birth order, you should get an asymmetric result.
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