16 ms·

Birth Order Effects Exist and Are Strong

259 points by imartin2k 9y ago

leoedin 9y ago
I would be interested to know how only children fall into this analysis. If the oldest child has more intellectual curiosity because they received more attention, you'd expect only children to have received even more attention still.
- andrewclunn 9y ago
  Or if it's the semi parental role the eldest often take regarding younger siblings
- erfgh 9y ago
  Yeah but then you have nobody to compare with.
  - theptip 9y ago
    The average of the population? (In this case, the average SSC reader.) If you have a big enough sample, you can ask if the average only child scores higher "Openness" than the average reader, or if their self-reported IQ is higher. That's a meaningful comparison I believe.
- deleted 9y ago
  [deleted]
searealist 9y ago
It's pretty likely that first born children were more likely to respond to the survey given that Scott openly stated he expected more first born children to be among his readership, giving people an impression that first born is better and they might feel good about themselves vs second born children who might feel bad about themselves.
- Yvain 9y ago
  I don't remember mentioning that prominently before the survey. Can you link me to the relevant quote?
  - searealist 9y ago
    https://slatestarcodex.com/2017/12/25/preregistration-of-hypotheses-for-the-ssc-survey/ https://slatestarcodex.com/2017/12/25/preregistration-of-hyp... 7. I plan to confirm or disprove, once and for all, whether our community has more older siblings. For lack of a fancier way to do this, I’ll take the set of all people who have exactly one sibling, and see what percent of them are older vs. younger. If it’s significantly above 50% older, I’m going to interpret this as a birth order effect. I’ll do the same with the set of people who have two siblings, three siblings, etc, and combine them all for a final determination. Half-siblings will be ignored. If you have any problems with this methodology, tell me now.
    - Yvain 9y ago
      That post starts with "Please don’t read on until you’ve taken it, since this could bias your results." But I checked the data I received before and after I posted that, and the birth order effects are about equally strong throughout.
      - searealist 9y ago
        And what % was before and what % after ?
        Yvain 9y ago
        5,523 before December 25, when I posted the pre-registrations. 2,254 after. Of the before-posting people, 2199 had exactly one sibling, and 71.1% of those were the older. Of the after-posting people, 776 had exactly one sibling, and 72.3% of those were older. A t-test revealed no difference between the two groups, p = 0.527.
olympus 9y ago
Sure they exist, but we don't want to talk about it. There is a strong motivation to be able to say that everyone is created equal, regardless of how uncontrollable factors affect you (birth order, height, race, gender). We don't want to kill someone's motivation to study for college just because they are a third child. But stereotypes exist for a reason. The hard part is separating hatred-based stereotypes from the stereotypes based on observations throughout history. Regarding birth order, the "middle child" stereotype is prevalent in Western society. Did the middle child stereotype spring from some sort of effort by first-borns to keep their lower-ranked siblings in line (a la racism?)? I doubt it. The middle child stereotype probably came from hundreds of years of observations. It's a similar story for the first-born and last-born stereotypes- they weren't created out of any prejudice, but probably from hundreds of years of mothers chatting about their kids. Like the article says, denying that the differences exist prevents us from ever finding out why (because people won't do research on something that doesn't exist). So let's acknowledge that some groups of people are different than other groups, and then respectfully do research to figure out why. The differences could be societal- perhaps first-borns are treated with more care by their parents, or they could be biological- perhaps the hormonal changes in a pregnant woman are different for each successive child, or they could be something else entirely- I had many of the same teachers as my older sister, and I often benefited from them having a pleasant experience with her, making my time in class much easier. But anyway, the first step is acknowleding that a difference exists, and that you aren't somehow "birth order-ist" just because you acknowledge that first-born kids often outscore lower order kids on many metrics.
- seszett 9y ago
  > Regarding birth order, the "middle child" stereotype is prevalent in Western society What is this stereotype though? I don't know about it - or about the others actually, but they were explained in the article.
  - watwut 9y ago
    I haven't heard about such prevalent stereotypes either. Stereotypes about women I did heard or stereotypes about races. I never heard anyone explain lack of success of child by saying "because he is second" or success of first as "first tend to be like it". Like, never.
dvfjsdhgfv 9y ago
This article is going to be flagged into oblivion into a few hours. We're not discussing the relationship between biological and psychological traits on HN.
- bildung 9y ago
  Alternative explanation: this article is just not good science. It: * doesn't control whether the not-first-borns are outside the target demographic (too old or too young) * doesn't look at children without siblings * more importantly: is just a cross section, so no causal relationships can be gleaned from that * also highly problematic: is self-selecting, with no discussion of the distribution of people not participating. With a poll question like that that alone invalidates every result, as obviously it invites bias towards readers who deem themselves smarter than their siblings * is not discussing, and controlling for, alternative explanations for the observed result All in all the margin of error is almost certainly a multiple of the effect size, thus rendering the results useless. Which they are anyway, because you can only answer a question like the one given in the article with longitudinal studies.
  - evanpw 9y ago
    Since birth order is immutable, what would you gain by a longitudinal study? You still only get one data point per person.
    - bildung 9y ago
      Sure, birth order is immutable, but you would gain multiple data points for "intellectual curiosity", which would be the point of the exercise.
rplnt 9y ago
This doesn't seem like a valid approach to me. To take a specific group, measure something, and assume that metric had an impact on them being in that group. It's interesting nevertheless.
- hamandcheese 9y ago
  Well I think it’s fair to say that membership in the group didn’t impact the participants birth order.
  - deleted 9y ago
    [deleted]
  - AstralStorm 9y ago
    It did. The data set is biased towards being older sibling about 3:1. If the statistical distribution is fully shown then it could be some sort of an argument.
    - AstralStorm 9y ago
      No idea about the downvote. This is a specific likely skewed sample. The study has to be reproduced on general population.
      - xyzzyz 9y ago
        What do you mean by "reproduced on general population"? This is explicitly a study of SSC readers. Obviously in general population you won't find that oldest siblings outnumber younger siblings by 3:1.
    - TheCoelacanth 9y ago
      A trans-humanist group might be more likely to have access to a time machine than most other groups, but I still don't think it is very likely that joining the group caused them to become a first-born child. It is much more likely that if there is a causal relationship, being a first-born child caused them to be more likely to join the group.
nl 9y ago
It's odd to discuss this without also mentioning the very strong apparent affects of birth order on sporting ability, eg [1]. I'd never heard of the supposed higher intelligence of first born, but I've heard a lot about the sporting side and anecdotally I've noticed it too (I am the oldest sibling in my family). [1] https://www.ncbi.nlm.nih.gov/pubmed/20435800 https://www.ncbi.nlm.nih.gov/pubmed/20435800
molszanski 9y ago
intellectual curiosity != slatestarcodex reader
- civilian 9y ago
  why?
  - molszanski 9y ago
    Let me illustrate this through an analogy. If the survey took place on a gun enthusiast website: - Fair claim: first borns are more likely to be gun enthusiasts - Far fetched claim: first borns have stronger personalities
    - Yvain 9y ago
      I agree with this, but the reason I'm focusing on intellectual curiosity was that of all the traits measured in the survey, it was the one that did show a significant effect of firstbornness, and it was also the only personality trait with a significant effect of firstbornness in Rohrer's study. I'm not just assuming it, I'm saying that two analyses showed it was the only trait that mattered, and then it suffices to explain the current data.
      - molszanski 9y ago
        I don't disagree. Findings are definitely interesting, promising and worth further investigation! I preach cautiousness in the name of finding the objective truth. One should be careful when testing a specific group of people.
buserror 9y ago
Wierd, I'm the youngest of 6, and I'm acknowledged by the others as the smartest of the lot, by quite a margin. "bloody little genius" has been my nickname since I'm about 8 ;-)
- jVinc 9y ago
  What's weird about that? On average men outrank woman in professional tennis, that doesn't make it weird that Serena Williams would utterly destroy me and most men on the courts 10 out 10 times. Single points aren't anti-points to statistical effects. Now if you happened to have a thousand friends that where also the youngest of 6 and happened to test higher on IQ scores, that would be weird. For more than one reason.
  - buserror 9y ago
    Well it IS wierd, because you would assume than that 'eldest child' principle would get at least linearly worse the more kids there are in a family... So I must be particularly lucky, OR perhaps we don't really have good numbers for the other end of the spectrum, regarding 'youngest child' general performances? Or, again, perhaps there is a large part of cultural bias ("eldest/heir" of the family being assumed as better) so given more attention/resources... And that since I'm from a family with a single mother (who didn't have time/inclination for that) I was spared that? In any case, I think making up "exists and are strong" conclusions without taking into account more parameters is simplistic at best...
    - AstralStorm 9y ago
      It is possible that like many other effects, firstborn effects are subject to law of big numbers. (Or some statistical distribution other than Gaussian.) Alternatively birth distance (time between births) or age of mother are the actual correlate. We do not know.
    - ema 9y ago
      Looking at the graphs in the article the difference between oldest and second oldest is much bigger than between subsequent ones.
deleted 9y ago
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owens99 9y ago
For me, the movie Gattaca perfectly captures the importance of nature vs nurture. The equalizer is how one responds to adversity.
- carlmr 9y ago
  Gattaca is feel-good-about-the-human-spirit fiction. I wouldn't use it as a source.
lumberjack 9y ago
To me it seems most likely that it is entirely due to environmental/nurturing reasons rather than some innate effect of being first out of their mother. For example money for school can vary, and the parents attitude towards nurturing thier children definitely does.
civilian 9y ago
There's a handful of comments kind of getting tripped up here. Scott is relying on a 1-2 punch-- First, that openness to experience was decently different in the two groups (73rd percentile vs 69 percentile) and then that most Big5 tests aren't done well. ( Big5 is a valid personality test-- it gets decent test/re-test scores, but it's still weak. Myers-Briggs fails because, despite being very similar to the Big5, it doesn't have good enough test/re-test scores.) Scott cites another study that says when you test openness properly, you get a wider distribution. So if you pair those two together, you get a decent sized effect. Maybe.
stupidcar 9y ago
This doesn't seem to be a "birth order" effect, so much as a "first born" effect. Once you get past the first child, there doesn't seem to be much influence. That makes me very skeptical of any biological explanation, as you would expect to see more of a tail-off. I think it's more likely a measurement error, or some subtle statistical effect caused by a combination of probability skewing and demographic changes.
- sevenfive 9y ago
  > I think it's more likely a measurement error, or some subtle statistical effect caused by a combination of probability skewing and demographic changes. Can you elaborate?
  - stupidcar 9y ago
    A possible statistical contribution I can think of is the skewness of the age distribution within the population of readers. Here is the distribution charted: https://docs.google.com/spreadsheets/u/1/d/e/2PACX-1vRrops3JL4ZDBo4CAygpEz_J8imEGB8GPekC1XAgZPM2s4mQT-ey1iefV3T2bjPKxkamFYifTYBBk74/pubchart?oid=312146988&format=interactive https://docs.google.com/spreadsheets/u/1/d/e/2PACX-1vRrops3J... Consider just the bins 20 (ages 10-20), 30 (ages 20-30) and 40 (ages 30-40). We can see that, of the three groups, teens are by far the least likely of these groups to read the blog, and people in their 20s are the most likely. Now consider two groups of two-sibling families that lie within this range, where one sibling is in one bin, and the other the next. E.g. the first group where one is a teenager, the first-born is in their twenties, and the second where one is in their 20s, and the first-born is their 30s. Case 1: If you take a random family from the [teen, 20s] group, how likely is it that the reader from this family is younger or first-born sibling? Since those in their 20s are much more likely to read the blog, it is much more likely that the reader is in their 20s, and is the first-born. Case 2: Now take a random family from the [20s, 30s] group. How likely is it that the reader is the younger sibling or the first-born? In this case, because readers in their 20s are more common than readers in their 30s, it is more likely that the reader is the younger sibling. However, the ratio of readers in their 30s to readers in their 20s is much closer than that between the 20s and teens. This makes it more likely in that in case 2 that the reader is still the first-born. Therefore, if the number of families in each group is equal, we would expect to see, in aggregate, more first-born readers than younger siblings. I'm not saying that this is happening in the actual data, you'd need to do more analysis, and probably need more data about the ages of siblings, or that it is a significant enough effect to cause the result found. But it demonstrates that statistical analysis can involve subtle effects that are not obvious without careful consideration. As such, we should be very wary of making any conclusions about causes, either birth order or anything else.
alkonaut 9y ago
There is also a disproportionate amount of people online that are born jan 01 1900, and have mothers with the maiden name "asdf". Several thousand % more than you would expect.
- rocqua 9y ago
  As explained in other comments[1], being the eldest sibling wasn't the default answer to a question. Instead, people were asked to enter into a text field their number of older brothers, older sisters, younger brothers, younger sisters. [1] https://news.ycombinator.com/item?id=16105462 https://news.ycombinator.com/item?id=16105462
hamandcheese 9y ago
Not an issue with this study, but possibly worth noting that, naturally, there must be more firstborns than subsequent-borns (not counting the generic middle-child grouping). This could lead to a larger preceived effect.
- kstenerud 9y ago
  Actually, it would be impossible for there to be more firstborns than subsequent-borns (barring death) because siblings require 2+ people, of which one and only one will be firstborn.
  - acdha 9y ago
    What if the number of only children is greater than the number of third children?
  - hamandcheese 9y ago
    For every second born, there must be a first born, but not vice versa. For every third born, there must be a second born and a first born, but not vice versa... So you're more likely to encounter a first born in the real world than any nth born, since some families will have only had one child.
- cbr 9y ago
  The survey asked for numbers of older brothers, younger brothers, older sisters, and younger sisters. The main analysis on the post is for people with one sibling, and there are exactly as many people with one sibling whose sibling is older as there are whose is younger.
  - hamandcheese 9y ago
    Again, not talking about the study, just the general notion that first borns/only children are more successful.
Tepix 9y ago
The reason is probably that the first child gets the most attention, right?
- teamhappy 9y ago
  Could be one factor. I read a thing the other day that said something about child birth triggering some sort of immune reaction in the mother's body. That could mean that the second child is born under slightly less ideal conditions or something like that.
belorn 9y ago
> But these demand strong effects of parenting on children’s later life outcomes, of exactly the sort that behavioral genetic studies consistently find not to exist Would like to hear more details to that claim. When ever I read about genetic factors (For example on the topic of depression), I keep hearing that without the environmental factors the genetic indicators loose their predictive power. Genetic factors in behavioral science make a person more effected by environmental factors, but alone the genetic factor tend to have no effect. To take the explicit example in the article. Is there an measurable effect in adult life that correlate to the amount parents focus and dedicate time to them as child? In rats I have heard enough studies to show a very strong correlation between stress in adult life and time that the rat got groomed as young by the mother. Could it be so simple that parents spend a bit more time/focus with the first child during the first few years, while the second child receive a bit less since there is now two children and the parents are a bit more experienced and feel more secure in parenting. While rats and humans are not identical, it is a strong hint that "parenting style" might carry an effect into adult life. Source: https://www.gwern.net/docs/genetics/2016-plomin.pdf https://www.gwern.net/docs/genetics/2016-plomin.pdf Although heritability estimates are significantly greater than 0%, they are also significantly less than 100%. As noted earlier, heritability estimates are substantial between 30% and 50%.... No traits are 100% heritable (e.g., Plomin, 1989; Turkheimer, 2000).
- tomp 9y ago
  Check out [1] - Top 10 Replicated Findings From Behavioral Genetics In particular, "all psychological traits show significant and substantial genetic influence" mostly contradicts your comment, also "the heritability of intelligence increases throughout development" - i.e. environmental factors (parenting) matter when kids is young, but less so when they turn into adults. [1] https://www.gwern.net/docs/genetics/2016-plomin.pdf https://www.gwern.net/docs/genetics/2016-plomin.pdf
  - belorn 9y ago
    from the abstract: Finally, we note that 4 of the top 10 findings (Findings 2, 7, 8, and 9) are about environmental influences rather than genetic influences. Via genetically sensitive designs such as twin studies, behavioral genetics has revealed almost as much about the environment as about genetics. You have to elaborate a bit more if your claim is that this paper disprove environmental influences. A second key aspect from the abstract: Most important, heritability does not imply immutability (Plominet al., 2013).
ACow_Adonis 9y ago
Speaking informally, but as a professional analyst here who is unfortunately at a computer with no analysis tools setup :( but who has worked with his fair share of social, survey and demographic information. Check your data. My first gut-instinct on seeing data like that is not "Eureka - i found a huge first-birth-order effect", but rather "huh...looks wrong, I wonder why that is?". What do I mean "looks wrong"? Keep in mind I have no real "pony in the race" on first-born effects (although I admit I am one), but intuitively it "doesn't look like real social data looks like". The effect is too big. Its too loud. Its too constant. Its too nice. Something else is driving it and its your job to find out what... The first place I'd look is data quality. Have you proven your data got into your final histogram data set right? I had problems with your csv opening it in libre office...looks like it interpreted it as having some value migration between the variable in whatever you did. Could be my computer, but in my experience, if there's a problem with the csv, these kind of things correlate with other mistakes. The second place i'd look is survey design: was there a default option, are people clicking through by default, are the response frequencies of other variables lining up as would be expected (gender, birthdays, that kind of thing). If not, why not? If you've crossed and ticked all those, only after that would I start the analysis...but again, a pattern and effect of that size and consistency is something that you should default to needing explained in the data. Reach the conclusion that its real only after you've eliminated everything else.
- aetherson 9y ago
  It wasn't a default option (you were asked to enter into a text field your number of older brothers, older sisters, younger brothers, younger sisters). He can't cross-reference by gender very well because his audience is overwhelmingly male, to the point where there's probably not a lot of statistical significance in the female audience. But yes, I think that these data are very open to an "impossibly hungry judges" critique. If birth order effects were so very visible and so very strong, why haven't we noticed them before?
  - ACow_Adonis 9y ago
    Anecdote time/thought experiment: and forgive me, I'm deliberately vague here. Pretend there's a business somewhere. Pretend they implemented a rule that said people had to enter a number/estimate into a box for a certain peice of information before they could proceed to the next box. Pretend as an analyst you're looking at the values resulting some way down the pipe from that data entry point. Do you think it reasonable to assume the distribution of numbers entered into that box that were invalid would be uniformally random? If the answer is no, what numbers do you think people would enter disproportionately?
utopkara 9y ago
Reading a random person rant about scientifying stuff, should perhaps be evenly distributed across siblings; until you realize that writing style does give away a lot about the person writing it. You can write a decently performing classifier that predicts gender (and several other demographics) from stuff they write, even from tweets, and chats. It would be stupid to think that people do not pick up the demographic clues in writing, and set their preferences accordingly.
- rocqua 9y ago
  Are you suggesting that the effect found could be explainedby first-borns liking the style of the blog rather then the content?
  - asdfaefasdf 9y ago
    His writing indicates he believes his readers are "more intelligent", and he believes that first borns are "more intelligent". So yeah, if you were a second born, who was more intelligent, you'd dismiss his blog as BS, and would not be counted among the survey respondents.
    - gjm11 9y ago
      For that to work, you (our hypothetical more-intelligent second-born) would need to: 1. Have seen Scott express the opinion that first-born children are more intelligent. 2. Interpreted that claim in a way incompatible with your own experience of being an intelligent second-born (e.g., taken Scott to be saying first-borns are always more intelligent). 3. Been sufficiently offended (or otherwise unimpressed) by this to stop reading his blog when you would otherwise have been happy to read it. For this to explain the apparent firstborn bias in Scott's survey respondents, thousands of potential readers would need to have done this. So, how plausible is it? 1. I've been reading Scott's blog for years and don't remember ever seeing him say anything like "first-born children are more intelligent" before this post we're discussing now. That doesn't mean he never did, and I'd be extremely unsurprised to find that he did -- but it does suggest that if he did it was easy to miss. 2. The distinction between "on average firstborns have an IQ one point or so higher than non-firstborns" and "firstborns are always smarter than not-firstborns" is not exactly subtle. 3. Well, anyone can get upset about anything, but this really doesn't seem to me like the sort of thing that would make thousands of people swear off an otherwise interesting blog in disgust. I'm going to rate it very implausible. No way is anything remotely like this a non-negligible fraction of the explanation for the apparent firstborn bias in Scott's survey respondents.
deleted 9y ago
[deleted]
saycheese 9y ago
Found the aggerate survey data: https://goo.gl/forms/8bmb7dwWyBtS5nDM2 https://goo.gl/forms/8bmb7dwWyBtS5nDM2 And it is pretty obvious the sample is bias, though take a look to see for yourself and comment if you notice anything too.
- aeorgnoieang 9y ago
  > And it is pretty obvious the sample is bias Sure, who's claiming otherwise?
- asdfaefasdf 9y ago
  1/3 of respondents are still in school. 2/3 of respondents have been reading the blog for >1 year. 94% consider the blog "favorable" Pretty skewed results.
  - gjm11 9y ago
    What do you mean by "skewed"? Obviously the SSC readership is a very long way from being an unbiased sample of (say) the whole world's population. No one would expect it to be, and in fact that's the point here: a survey of people who are obviously unusual in some respects (whatever combination of quirks turns someone into a likely SSC reader) turns out to be unusual in another respect with no obvious connection, namely having substantially more firstborn children than you'd expect. Whatever it is that makes someone more likely to read SSC, it seems like it's probably a combination of things that surely can't correlate with birth order (e.g., being a native English speaker) and, broadly speaking, personality traits (e.g., being interested in the sort of thing Scott writes). So the results show evidence of a link between birth order and personality, and (from the survey results) apparently a strong one. Which is interesting if true. And all of this only works because the SSC readership is far from typical of the population of a whole. So, again, what do you mean by "skewed"? And why is it a problem?
psynapse 9y ago
For those interested in the topic, I can recommend Judith Rich Harris' superb book, The Nurture Assumption[1]. It mostly deals with debunking common views on parent->child effects, but includes some material on birth order effects. [1] https://jamesclear.com/book-summaries/nurture-assumption https://jamesclear.com/book-summaries/nurture-assumption
testplzignore 9y ago
> It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. That can’t explain why one group reads this blog so much more often than the other. It would be interesting to investigate the relationship between the age of the respondent and the effect of birth order. For example, does birth order matter less for millennials than it does for baby boomers, or vice versa? Also would be interesting to investigate how much the age difference between siblings matter. For example, does birth order matter more if the siblings are born 1 year apart vs 10 years apart?
- guelo 9y ago
  You can download the data if you want to do those analyses.
torgoguys 9y ago
For an effect this prevalent and strong my first reaction is "check your data." Then I read this: >It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. And I really start thinking you have to check your data. The average age difference in that cohort is only one year and humans have a 9 month gestation. Something is likely wrong with your data or your sample.
- CarVac 9y ago
  He clarified in the comments > No, the difference between the average age of all older siblings taking the survey, and the average age of all younger siblings taking the survey, was one year.
chrisbrandow 9y ago
The birth order effect is fascinating to me because my bias is to trust the scientific consensus, but as a parent I see such obvious patterns in my children and in the dozens of friends kids that I’ve watched over the years. It’s hard to reconcile.
- _red 9y ago
  Fully agreed, its uncanny when you see it in person. It makes sense from a genetic perspective: Similar how to allocate investment funds (primary funds in safe conservative investments, additional funds in more speculative 'moonshot' investments).
- losteverything 9y ago
  but as a parent I see such obvious patterns Birth order is real and parenting is not data science. Remember the easy birth order question? How many pictures of you do your parents have (pr take)? If u r a FB many! Less and less as kids continue
- furyofantares 9y ago
  Perhaps there is a birth order perception effect in parents.
tallanvor 9y ago
The author is cherry picking studies to try and prove his hypothesis, ignoring that the "studies" he cites show only a possible correlation. First, he's taking the results of a voluntary survey of users of his own site. He'd be better off asking a polling firm to randomly contact people, ask if they regularly read any more well-known sites that are more "intellectual" in nature, and then ask about the person's birth order. Second, he uses anecdotal data about Harvard students, which ignores several potential sources of bias. As one example: Harvard is expensive, and students are more likely to come from families with large incomes. High-income families have fewer children. Another example: younger siblings often specifically don't want to go to the same school as their older siblings, so if an older sibling gets into Harvard, they are less likely to bother applying. There's also a bit about males being more likely to be gay based on having more older brothers. I could probably spend an hour listing reasons you shouldn't take that research seriously.
- naasking 9y ago
  > The author is cherry picking studies to try and prove his hypothesis, ignoring that the "studies" he cites show only a possible correlation Not really, he starts out explaining that most previous research on birth order effects was well and truly debunked. This doesn't disprove the existence of birth order effects, and he makes a decent case. > First, he's taking the results of a voluntary survey of users of his own site And he thoroughly discusses the self-selection bias. > Another example: younger siblings often specifically don't want to go to the same school as their older siblings, so if an older sibling gets into Harvard, they are less likely to bother applying. If first-borns are more likely to go to Harvard, that's a birth order effect too. If they're not more likely to go to Harvard, then Harvard should have an even mix of birth orders and so aren't subject to the bias you point out.
losteverything 9y ago
Few things helped me more understanding people and family than knowledge of birth order. First born, middle, baby, only... Quite helpful as how to understand and predict people's actions. And how to communicate with them. Also, the cases where the first born or first son being expected to behave like a FB but are naturally not...often they dont realize this until adulthood. The book by Leman (The Birth Order Book) i bought shortly after entering the workforce. A great read.
tgb 9y ago
I was taught birth order effects in middle school in the 2000's in the US in a "health" class (in the same unit we also did handwriting analysis). We were literally shown a video of a family in which everyone explained why they were the rebel as the second child, the overachiever as the first child, the spoiled brat as the youngest, etc. Birth order effects might exist... but even if that were true we should not teach them to middle-schoolers as determining their life. This is for the same reason that we would not want a video of a "typical community" showing a white male doctor, a white female kindergarten teacher, and a black male janitor even if all of those occupations are statistically more likely to be held by those demographics than the others. Because we live in a time and a place where children get to choose that they are not like their statistical cohort if they put their mind to it. The only positive thing I took out of that class was the number of other students going "this is bullshit, I'm a first child and am the rebel of the family" or whatever. And it was a good introduction to not trusting authority.
- AstralStorm 9y ago
  Devil's advocate here: why shouldn't we teach people their position in life is largely predetermined? We have precedent in Confucian and Hinduist philosophies. If it isn't, wouldn't we state so? I am looking for an utilitarian valid and true argument.
  - pas 9y ago
    We should teach people about these things that have a great effect on their life trajectory, but maybe, just maybe, middle-schoolers are not ready to appreciate the complex interplay between overlapping Gauss curves, path dependence, self-fulfilling prophecies. Of course people should know where they come from and what does that mean, just as it's usually important to tell kids if they are adopted or have some serious congenital problem. (Usually because it can mean life or death, as we all seen it in [medical] dramas where people search for organ donors and so on.) But the question of when and how to tell is a big one, and there are probably many good answers, but alas probably all of them are forged in hard compromises between hurting the kid now, or letting them finding it out by accident.
canjobear 9y ago
Didn't he also run a control condition on Mechanical Turk? Why isn't that analyzed here to show the effect?
gonational 9y ago
Middle child here. I didn’t like the methodology of this study, so I did my own little study, my wife being the core respondent. The results were astounding and the P value is off the charts (higher is better in this case - trust me). Conclusion: middle children are the best
- thrav 9y ago
  Has this conclusion ever been called into question?
godelski 9y ago
Anyone else find it strange that the author used SAT scores as a metric for intelligence? I think it is kind of absurd to think that a test that is specifically not designed to test intelligence and designed to give trick or misleading questions is a good metric. Not to say there isn't a decent correlation between intelligence and test scores, but a significant amount of people fall through the cracks. From what I understand, even the academic communities don't place a lot of weight on tests like SAT, ACT, GRE, etc. I think it is fine to use this method to measure intelligence, but not in isolation.
- skybrian 9y ago
  The survey asked for both SAT and IQ scores, but both questions were optional.
- dragonwriter 9y ago
  > Anyone else find it strange that the author used SAT scores as a metric for intelligence Since SAT scores are very highly correlated with IQ test scores, and they are often more available, no, not at all. I'm much more concerned with how the sample (if it can even be called that) was generated, which kind of makes the whole thing worthless. The pointers to peer-reviewed studies (even though almost certainly cherry-picked) are more useful than the original “research” reported.
  - godelski 9y ago
    Like I said, there is a correlation, but I definitely would not argue that it is "very highly correlated". I found one paper by Frey [1] that discusses a significant correlation, but you will see that it is definitely not the "very highly" that you claim. I only gave a quick glance of the article, but I'm not even sold on its results because their methods suggest they might be over fitting the data (them just trying different fit methods to yield better results feels sketchy. Maybe they back it up better than I saw over the quick glance). That all being said, correlation itself is not a de facto proof nor does it mean it is a good metric. There is a 99.8% correlation (which I'd call "very highly correlated") between US spending on science/space/technology and deaths by strangulation/hanging/suffocation[2]. I think we can all see that it would be laughable to use one as a predictor of the other. Yeah, this example is ludicrous and obvious, but the difficult part is when you expect things to be dependent (which is what we are seeking for a good metric, not correlation), but aren't. It is easy to find data to match the results you are looking for, but that doesn't mean they are good results. [1] https://www.psychologicalscience.org/pdf/ps/Frey.pdf?origin=publication_detail https://www.psychologicalscience.org/pdf/ps/Frey.pdf?origin=... [2] http://www.tylervigen.com/spurious-correlations http://www.tylervigen.com/spurious-correlations
workthrowaway27 9y ago
Wow, I'm impressed that the average IQ of Scott's readership is so high (at least if you use SAT as a proxy for IQ).
ggggtez 9y ago
Not convinced. What about the effect of selection bias? That done probably accounts for the entire "study"
KirinDave 9y ago
> It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. That can’t explain why one group reads this blog so much more often than the other So, uh... People understand that "average difference" is a miserable plan here right?
- deleted 9y ago
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trgv 9y ago
I thought it was conventional wisdom that sexual orientation in males is influenced by birth order. If that's the case then I'd be surprised if there were no other effects. https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male_sexual_orientation https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male...
- Froyoh 9y ago
  Huh. First time hearing about this!
JustSomeNobody 9y ago
Anecdata. My older brother was as smart as a box of rocks. Even given that, he was an under achiever. He would couch surf and mooch off anyone. He would work a job until the first pay check then quit. If there was ever a reason to be against UBI, he was it. I would tell my mom he's like that first pancake that just doesn't turn out right because you rushed. I, on the other hand, became an engineer.
- dragonwriter 9y ago
  I dunno, sounds to me like your brother is the kind of person whose need for money a d resulting intermittent attachment to the labor forces drives down efficiency and wages and, as such, is an argument for UBI rather than against it.
mcguire 9y ago
"I first started thinking this at transhumanist meetups, when it would occasionally come up that everyone there was an oldest child." Alternative hypothesis: first-born children wish to escape their siblings so much that they would prefer to leave the species.
- AstralStorm 9y ago
  This is not what is being analysed and either conclusion is data dredging.
doku 9y ago
There are some articles on HN about boredom and creativity. Perhaps its just that firstborn have more time alone. It'd be interesting to see age differences vs creativity.
gaius 9y ago
I’ve often thought that certain jobs should only be open to first borns. Jobs with serious responsibilities.

259 points by imartin2k 9y ago

I would be interested to know how only children fall into this analysis. If the oldest child has more intellectual curiosity because they received more attention, you'd expect only children to have received even more attention still.

andrewclunn 9y ago
Or if it's the semi parental role the eldest often take regarding younger siblings
erfgh 9y ago
Yeah but then you have nobody to compare with.
- theptip 9y ago
  The average of the population? (In this case, the average SSC reader.) If you have a big enough sample, you can ask if the average only child scores higher "Openness" than the average reader, or if their self-reported IQ is higher. That's a meaningful comparison I believe.
deleted 9y ago
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searealist 9y ago

It's pretty likely that first born children were more likely to respond to the survey given that Scott openly stated he expected more first born children to be among his readership, giving people an impression that first born is better and they might feel good about themselves vs second born children who might feel bad about themselves.

Yvain 9y ago
I don't remember mentioning that prominently before the survey. Can you link me to the relevant quote?
- searealist 9y ago
  https://slatestarcodex.com/2017/12/25/preregistration-of-hypotheses-for-the-ssc-survey/ https://slatestarcodex.com/2017/12/25/preregistration-of-hyp... 7. I plan to confirm or disprove, once and for all, whether our community has more older siblings. For lack of a fancier way to do this, I’ll take the set of all people who have exactly one sibling, and see what percent of them are older vs. younger. If it’s significantly above 50% older, I’m going to interpret this as a birth order effect. I’ll do the same with the set of people who have two siblings, three siblings, etc, and combine them all for a final determination. Half-siblings will be ignored. If you have any problems with this methodology, tell me now.
  - Yvain 9y ago
    That post starts with "Please don’t read on until you’ve taken it, since this could bias your results." But I checked the data I received before and after I posted that, and the birth order effects are about equally strong throughout.
    - searealist 9y ago
      And what % was before and what % after ?
      - Yvain 9y ago
        5,523 before December 25, when I posted the pre-registrations. 2,254 after. Of the before-posting people, 2199 had exactly one sibling, and 71.1% of those were the older. Of the after-posting people, 776 had exactly one sibling, and 72.3% of those were older. A t-test revealed no difference between the two groups, p = 0.527.

olympus 9y ago

Sure they exist, but we don't want to talk about it. There is a strong motivation to be able to say that everyone is created equal, regardless of how uncontrollable factors affect you (birth order, height, race, gender). We don't want to kill someone's motivation to study for college just because they are a third child. But stereotypes exist for a reason. The hard part is separating hatred-based stereotypes from the stereotypes based on observations throughout history. Regarding birth order, the "middle child" stereotype is prevalent in Western society. Did the middle child stereotype spring from some sort of effort by first-borns to keep their lower-ranked siblings in line (a la racism?)? I doubt it. The middle child stereotype probably came from hundreds of years of observations. It's a similar story for the first-born and last-born stereotypes- they weren't created out of any prejudice, but probably from hundreds of years of mothers chatting about their kids. Like the article says, denying that the differences exist prevents us from ever finding out why (because people won't do research on something that doesn't exist). So let's acknowledge that some groups of people are different than other groups, and then respectfully do research to figure out why. The differences could be societal- perhaps first-borns are treated with more care by their parents, or they could be biological- perhaps the hormonal changes in a pregnant woman are different for each successive child, or they could be something else entirely- I had many of the same teachers as my older sister, and I often benefited from them having a pleasant experience with her, making my time in class much easier. But anyway, the first step is acknowleding that a difference exists, and that you aren't somehow "birth order-ist" just because you acknowledge that first-born kids often outscore lower order kids on many metrics.

seszett 9y ago
> Regarding birth order, the "middle child" stereotype is prevalent in Western society What is this stereotype though? I don't know about it - or about the others actually, but they were explained in the article.
- watwut 9y ago
  I haven't heard about such prevalent stereotypes either. Stereotypes about women I did heard or stereotypes about races. I never heard anyone explain lack of success of child by saying "because he is second" or success of first as "first tend to be like it". Like, never.

dvfjsdhgfv 9y ago

This article is going to be flagged into oblivion into a few hours. We're not discussing the relationship between biological and psychological traits on HN.

bildung 9y ago
Alternative explanation: this article is just not good science. It: * doesn't control whether the not-first-borns are outside the target demographic (too old or too young) * doesn't look at children without siblings * more importantly: is just a cross section, so no causal relationships can be gleaned from that * also highly problematic: is self-selecting, with no discussion of the distribution of people not participating. With a poll question like that that alone invalidates every result, as obviously it invites bias towards readers who deem themselves smarter than their siblings * is not discussing, and controlling for, alternative explanations for the observed result All in all the margin of error is almost certainly a multiple of the effect size, thus rendering the results useless. Which they are anyway, because you can only answer a question like the one given in the article with longitudinal studies.
- evanpw 9y ago
  Since birth order is immutable, what would you gain by a longitudinal study? You still only get one data point per person.
  - bildung 9y ago
    Sure, birth order is immutable, but you would gain multiple data points for "intellectual curiosity", which would be the point of the exercise.

rplnt 9y ago

This doesn't seem like a valid approach to me. To take a specific group, measure something, and assume that metric had an impact on them being in that group. It's interesting nevertheless.

hamandcheese 9y ago
Well I think it’s fair to say that membership in the group didn’t impact the participants birth order.
- deleted 9y ago
  [deleted]
- AstralStorm 9y ago
  It did. The data set is biased towards being older sibling about 3:1. If the statistical distribution is fully shown then it could be some sort of an argument.
  - AstralStorm 9y ago
    No idea about the downvote. This is a specific likely skewed sample. The study has to be reproduced on general population.
    - xyzzyz 9y ago
      What do you mean by "reproduced on general population"? This is explicitly a study of SSC readers. Obviously in general population you won't find that oldest siblings outnumber younger siblings by 3:1.
  - TheCoelacanth 9y ago
    A trans-humanist group might be more likely to have access to a time machine than most other groups, but I still don't think it is very likely that joining the group caused them to become a first-born child. It is much more likely that if there is a causal relationship, being a first-born child caused them to be more likely to join the group.

nl 9y ago

It's odd to discuss this without also mentioning the very strong apparent affects of birth order on sporting ability, eg [1]. I'd never heard of the supposed higher intelligence of first born, but I've heard a lot about the sporting side and anecdotally I've noticed it too (I am the oldest sibling in my family). [1] https://www.ncbi.nlm.nih.gov/pubmed/20435800 https://www.ncbi.nlm.nih.gov/pubmed/20435800

molszanski 9y ago

intellectual curiosity != slatestarcodex reader

civilian 9y ago
why?
- molszanski 9y ago
  Let me illustrate this through an analogy. If the survey took place on a gun enthusiast website: - Fair claim: first borns are more likely to be gun enthusiasts - Far fetched claim: first borns have stronger personalities
  - Yvain 9y ago
    I agree with this, but the reason I'm focusing on intellectual curiosity was that of all the traits measured in the survey, it was the one that did show a significant effect of firstbornness, and it was also the only personality trait with a significant effect of firstbornness in Rohrer's study. I'm not just assuming it, I'm saying that two analyses showed it was the only trait that mattered, and then it suffices to explain the current data.
    - molszanski 9y ago
      I don't disagree. Findings are definitely interesting, promising and worth further investigation! I preach cautiousness in the name of finding the objective truth. One should be careful when testing a specific group of people.

buserror 9y ago

Wierd, I'm the youngest of 6, and I'm acknowledged by the others as the smartest of the lot, by quite a margin. "bloody little genius" has been my nickname since I'm about 8 ;-)

jVinc 9y ago
What's weird about that? On average men outrank woman in professional tennis, that doesn't make it weird that Serena Williams would utterly destroy me and most men on the courts 10 out 10 times. Single points aren't anti-points to statistical effects. Now if you happened to have a thousand friends that where also the youngest of 6 and happened to test higher on IQ scores, that would be weird. For more than one reason.
- buserror 9y ago
  Well it IS wierd, because you would assume than that 'eldest child' principle would get at least linearly worse the more kids there are in a family... So I must be particularly lucky, OR perhaps we don't really have good numbers for the other end of the spectrum, regarding 'youngest child' general performances? Or, again, perhaps there is a large part of cultural bias ("eldest/heir" of the family being assumed as better) so given more attention/resources... And that since I'm from a family with a single mother (who didn't have time/inclination for that) I was spared that? In any case, I think making up "exists and are strong" conclusions without taking into account more parameters is simplistic at best...
  - AstralStorm 9y ago
    It is possible that like many other effects, firstborn effects are subject to law of big numbers. (Or some statistical distribution other than Gaussian.) Alternatively birth distance (time between births) or age of mother are the actual correlate. We do not know.
  - ema 9y ago
    Looking at the graphs in the article the difference between oldest and second oldest is much bigger than between subsequent ones.

deleted 9y ago

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owens99 9y ago

For me, the movie Gattaca perfectly captures the importance of nature vs nurture. The equalizer is how one responds to adversity.

carlmr 9y ago
Gattaca is feel-good-about-the-human-spirit fiction. I wouldn't use it as a source.

lumberjack 9y ago

To me it seems most likely that it is entirely due to environmental/nurturing reasons rather than some innate effect of being first out of their mother. For example money for school can vary, and the parents attitude towards nurturing thier children definitely does.

civilian 9y ago

There's a handful of comments kind of getting tripped up here. Scott is relying on a 1-2 punch-- First, that openness to experience was decently different in the two groups (73rd percentile vs 69 percentile) and then that most Big5 tests aren't done well. ( Big5 is a valid personality test-- it gets decent test/re-test scores, but it's still weak. Myers-Briggs fails because, despite being very similar to the Big5, it doesn't have good enough test/re-test scores.) Scott cites another study that says when you test openness properly, you get a wider distribution. So if you pair those two together, you get a decent sized effect. Maybe.

stupidcar 9y ago

This doesn't seem to be a "birth order" effect, so much as a "first born" effect. Once you get past the first child, there doesn't seem to be much influence. That makes me very skeptical of any biological explanation, as you would expect to see more of a tail-off. I think it's more likely a measurement error, or some subtle statistical effect caused by a combination of probability skewing and demographic changes.

sevenfive 9y ago
> I think it's more likely a measurement error, or some subtle statistical effect caused by a combination of probability skewing and demographic changes. Can you elaborate?
- stupidcar 9y ago
  A possible statistical contribution I can think of is the skewness of the age distribution within the population of readers. Here is the distribution charted: https://docs.google.com/spreadsheets/u/1/d/e/2PACX-1vRrops3JL4ZDBo4CAygpEz_J8imEGB8GPekC1XAgZPM2s4mQT-ey1iefV3T2bjPKxkamFYifTYBBk74/pubchart?oid=312146988&format=interactive https://docs.google.com/spreadsheets/u/1/d/e/2PACX-1vRrops3J... Consider just the bins 20 (ages 10-20), 30 (ages 20-30) and 40 (ages 30-40). We can see that, of the three groups, teens are by far the least likely of these groups to read the blog, and people in their 20s are the most likely. Now consider two groups of two-sibling families that lie within this range, where one sibling is in one bin, and the other the next. E.g. the first group where one is a teenager, the first-born is in their twenties, and the second where one is in their 20s, and the first-born is their 30s. Case 1: If you take a random family from the [teen, 20s] group, how likely is it that the reader from this family is younger or first-born sibling? Since those in their 20s are much more likely to read the blog, it is much more likely that the reader is in their 20s, and is the first-born. Case 2: Now take a random family from the [20s, 30s] group. How likely is it that the reader is the younger sibling or the first-born? In this case, because readers in their 20s are more common than readers in their 30s, it is more likely that the reader is the younger sibling. However, the ratio of readers in their 30s to readers in their 20s is much closer than that between the 20s and teens. This makes it more likely in that in case 2 that the reader is still the first-born. Therefore, if the number of families in each group is equal, we would expect to see, in aggregate, more first-born readers than younger siblings. I'm not saying that this is happening in the actual data, you'd need to do more analysis, and probably need more data about the ages of siblings, or that it is a significant enough effect to cause the result found. But it demonstrates that statistical analysis can involve subtle effects that are not obvious without careful consideration. As such, we should be very wary of making any conclusions about causes, either birth order or anything else.

alkonaut 9y ago

There is also a disproportionate amount of people online that are born jan 01 1900, and have mothers with the maiden name "asdf". Several thousand % more than you would expect.

rocqua 9y ago
As explained in other comments[1], being the eldest sibling wasn't the default answer to a question. Instead, people were asked to enter into a text field their number of older brothers, older sisters, younger brothers, younger sisters. [1] https://news.ycombinator.com/item?id=16105462 https://news.ycombinator.com/item?id=16105462

hamandcheese 9y ago

Not an issue with this study, but possibly worth noting that, naturally, there must be more firstborns than subsequent-borns (not counting the generic middle-child grouping). This could lead to a larger preceived effect.

kstenerud 9y ago
Actually, it would be impossible for there to be more firstborns than subsequent-borns (barring death) because siblings require 2+ people, of which one and only one will be firstborn.
- acdha 9y ago
  What if the number of only children is greater than the number of third children?
- hamandcheese 9y ago
  For every second born, there must be a first born, but not vice versa. For every third born, there must be a second born and a first born, but not vice versa... So you're more likely to encounter a first born in the real world than any nth born, since some families will have only had one child.
cbr 9y ago
The survey asked for numbers of older brothers, younger brothers, older sisters, and younger sisters. The main analysis on the post is for people with one sibling, and there are exactly as many people with one sibling whose sibling is older as there are whose is younger.
- hamandcheese 9y ago
  Again, not talking about the study, just the general notion that first borns/only children are more successful.

Tepix 9y ago

The reason is probably that the first child gets the most attention, right?

teamhappy 9y ago
Could be one factor. I read a thing the other day that said something about child birth triggering some sort of immune reaction in the mother's body. That could mean that the second child is born under slightly less ideal conditions or something like that.

belorn 9y ago

> But these demand strong effects of parenting on children’s later life outcomes, of exactly the sort that behavioral genetic studies consistently find not to exist Would like to hear more details to that claim. When ever I read about genetic factors (For example on the topic of depression), I keep hearing that without the environmental factors the genetic indicators loose their predictive power. Genetic factors in behavioral science make a person more effected by environmental factors, but alone the genetic factor tend to have no effect. To take the explicit example in the article. Is there an measurable effect in adult life that correlate to the amount parents focus and dedicate time to them as child? In rats I have heard enough studies to show a very strong correlation between stress in adult life and time that the rat got groomed as young by the mother. Could it be so simple that parents spend a bit more time/focus with the first child during the first few years, while the second child receive a bit less since there is now two children and the parents are a bit more experienced and feel more secure in parenting. While rats and humans are not identical, it is a strong hint that "parenting style" might carry an effect into adult life. Source: https://www.gwern.net/docs/genetics/2016-plomin.pdf https://www.gwern.net/docs/genetics/2016-plomin.pdf Although heritability estimates are significantly greater than 0%, they are also significantly less than 100%. As noted earlier, heritability estimates are substantial between 30% and 50%.... No traits are 100% heritable (e.g., Plomin, 1989; Turkheimer, 2000).

tomp 9y ago
Check out [1] - Top 10 Replicated Findings From Behavioral Genetics In particular, "all psychological traits show significant and substantial genetic influence" mostly contradicts your comment, also "the heritability of intelligence increases throughout development" - i.e. environmental factors (parenting) matter when kids is young, but less so when they turn into adults. [1] https://www.gwern.net/docs/genetics/2016-plomin.pdf https://www.gwern.net/docs/genetics/2016-plomin.pdf
- belorn 9y ago
  from the abstract: Finally, we note that 4 of the top 10 findings (Findings 2, 7, 8, and 9) are about environmental influences rather than genetic influences. Via genetically sensitive designs such as twin studies, behavioral genetics has revealed almost as much about the environment as about genetics. You have to elaborate a bit more if your claim is that this paper disprove environmental influences. A second key aspect from the abstract: Most important, heritability does not imply immutability (Plominet al., 2013).

ACow_Adonis 9y ago

Speaking informally, but as a professional analyst here who is unfortunately at a computer with no analysis tools setup :( but who has worked with his fair share of social, survey and demographic information. Check your data. My first gut-instinct on seeing data like that is not "Eureka - i found a huge first-birth-order effect", but rather "huh...looks wrong, I wonder why that is?". What do I mean "looks wrong"? Keep in mind I have no real "pony in the race" on first-born effects (although I admit I am one), but intuitively it "doesn't look like real social data looks like". The effect is too big. Its too loud. Its too constant. Its too nice. Something else is driving it and its your job to find out what... The first place I'd look is data quality. Have you proven your data got into your final histogram data set right? I had problems with your csv opening it in libre office...looks like it interpreted it as having some value migration between the variable in whatever you did. Could be my computer, but in my experience, if there's a problem with the csv, these kind of things correlate with other mistakes. The second place i'd look is survey design: was there a default option, are people clicking through by default, are the response frequencies of other variables lining up as would be expected (gender, birthdays, that kind of thing). If not, why not? If you've crossed and ticked all those, only after that would I start the analysis...but again, a pattern and effect of that size and consistency is something that you should default to needing explained in the data. Reach the conclusion that its real only after you've eliminated everything else.

aetherson 9y ago
It wasn't a default option (you were asked to enter into a text field your number of older brothers, older sisters, younger brothers, younger sisters). He can't cross-reference by gender very well because his audience is overwhelmingly male, to the point where there's probably not a lot of statistical significance in the female audience. But yes, I think that these data are very open to an "impossibly hungry judges" critique. If birth order effects were so very visible and so very strong, why haven't we noticed them before?
- ACow_Adonis 9y ago
  Anecdote time/thought experiment: and forgive me, I'm deliberately vague here. Pretend there's a business somewhere. Pretend they implemented a rule that said people had to enter a number/estimate into a box for a certain peice of information before they could proceed to the next box. Pretend as an analyst you're looking at the values resulting some way down the pipe from that data entry point. Do you think it reasonable to assume the distribution of numbers entered into that box that were invalid would be uniformally random? If the answer is no, what numbers do you think people would enter disproportionately?

utopkara 9y ago

Reading a random person rant about scientifying stuff, should perhaps be evenly distributed across siblings; until you realize that writing style does give away a lot about the person writing it. You can write a decently performing classifier that predicts gender (and several other demographics) from stuff they write, even from tweets, and chats. It would be stupid to think that people do not pick up the demographic clues in writing, and set their preferences accordingly.

rocqua 9y ago
Are you suggesting that the effect found could be explainedby first-borns liking the style of the blog rather then the content?
- asdfaefasdf 9y ago
  His writing indicates he believes his readers are "more intelligent", and he believes that first borns are "more intelligent". So yeah, if you were a second born, who was more intelligent, you'd dismiss his blog as BS, and would not be counted among the survey respondents.
  - gjm11 9y ago
    For that to work, you (our hypothetical more-intelligent second-born) would need to: 1. Have seen Scott express the opinion that first-born children are more intelligent. 2. Interpreted that claim in a way incompatible with your own experience of being an intelligent second-born (e.g., taken Scott to be saying first-borns are always more intelligent). 3. Been sufficiently offended (or otherwise unimpressed) by this to stop reading his blog when you would otherwise have been happy to read it. For this to explain the apparent firstborn bias in Scott's survey respondents, thousands of potential readers would need to have done this. So, how plausible is it? 1. I've been reading Scott's blog for years and don't remember ever seeing him say anything like "first-born children are more intelligent" before this post we're discussing now. That doesn't mean he never did, and I'd be extremely unsurprised to find that he did -- but it does suggest that if he did it was easy to miss. 2. The distinction between "on average firstborns have an IQ one point or so higher than non-firstborns" and "firstborns are always smarter than not-firstborns" is not exactly subtle. 3. Well, anyone can get upset about anything, but this really doesn't seem to me like the sort of thing that would make thousands of people swear off an otherwise interesting blog in disgust. I'm going to rate it very implausible. No way is anything remotely like this a non-negligible fraction of the explanation for the apparent firstborn bias in Scott's survey respondents.

deleted 9y ago

[deleted]

saycheese 9y ago

Found the aggerate survey data: https://goo.gl/forms/8bmb7dwWyBtS5nDM2 https://goo.gl/forms/8bmb7dwWyBtS5nDM2 And it is pretty obvious the sample is bias, though take a look to see for yourself and comment if you notice anything too.

aeorgnoieang 9y ago
> And it is pretty obvious the sample is bias Sure, who's claiming otherwise?
asdfaefasdf 9y ago
1/3 of respondents are still in school. 2/3 of respondents have been reading the blog for >1 year. 94% consider the blog "favorable" Pretty skewed results.
- gjm11 9y ago
  What do you mean by "skewed"? Obviously the SSC readership is a very long way from being an unbiased sample of (say) the whole world's population. No one would expect it to be, and in fact that's the point here: a survey of people who are obviously unusual in some respects (whatever combination of quirks turns someone into a likely SSC reader) turns out to be unusual in another respect with no obvious connection, namely having substantially more firstborn children than you'd expect. Whatever it is that makes someone more likely to read SSC, it seems like it's probably a combination of things that surely can't correlate with birth order (e.g., being a native English speaker) and, broadly speaking, personality traits (e.g., being interested in the sort of thing Scott writes). So the results show evidence of a link between birth order and personality, and (from the survey results) apparently a strong one. Which is interesting if true. And all of this only works because the SSC readership is far from typical of the population of a whole. So, again, what do you mean by "skewed"? And why is it a problem?

psynapse 9y ago

For those interested in the topic, I can recommend Judith Rich Harris' superb book, The Nurture Assumption[1]. It mostly deals with debunking common views on parent->child effects, but includes some material on birth order effects. [1] https://jamesclear.com/book-summaries/nurture-assumption https://jamesclear.com/book-summaries/nurture-assumption

testplzignore 9y ago

> It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. That can’t explain why one group reads this blog so much more often than the other. It would be interesting to investigate the relationship between the age of the respondent and the effect of birth order. For example, does birth order matter less for millennials than it does for baby boomers, or vice versa? Also would be interesting to investigate how much the age difference between siblings matter. For example, does birth order matter more if the siblings are born 1 year apart vs 10 years apart?

guelo 9y ago
You can download the data if you want to do those analyses.

torgoguys 9y ago

For an effect this prevalent and strong my first reaction is "check your data." Then I read this: >It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. And I really start thinking you have to check your data. The average age difference in that cohort is only one year and humans have a 9 month gestation. Something is likely wrong with your data or your sample.

CarVac 9y ago
He clarified in the comments > No, the difference between the average age of all older siblings taking the survey, and the average age of all younger siblings taking the survey, was one year.

chrisbrandow 9y ago

The birth order effect is fascinating to me because my bias is to trust the scientific consensus, but as a parent I see such obvious patterns in my children and in the dozens of friends kids that I’ve watched over the years. It’s hard to reconcile.

_red 9y ago
Fully agreed, its uncanny when you see it in person. It makes sense from a genetic perspective: Similar how to allocate investment funds (primary funds in safe conservative investments, additional funds in more speculative 'moonshot' investments).
losteverything 9y ago
but as a parent I see such obvious patterns Birth order is real and parenting is not data science. Remember the easy birth order question? How many pictures of you do your parents have (pr take)? If u r a FB many! Less and less as kids continue
furyofantares 9y ago
Perhaps there is a birth order perception effect in parents.

tallanvor 9y ago

The author is cherry picking studies to try and prove his hypothesis, ignoring that the "studies" he cites show only a possible correlation. First, he's taking the results of a voluntary survey of users of his own site. He'd be better off asking a polling firm to randomly contact people, ask if they regularly read any more well-known sites that are more "intellectual" in nature, and then ask about the person's birth order. Second, he uses anecdotal data about Harvard students, which ignores several potential sources of bias. As one example: Harvard is expensive, and students are more likely to come from families with large incomes. High-income families have fewer children. Another example: younger siblings often specifically don't want to go to the same school as their older siblings, so if an older sibling gets into Harvard, they are less likely to bother applying. There's also a bit about males being more likely to be gay based on having more older brothers. I could probably spend an hour listing reasons you shouldn't take that research seriously.

naasking 9y ago
> The author is cherry picking studies to try and prove his hypothesis, ignoring that the "studies" he cites show only a possible correlation Not really, he starts out explaining that most previous research on birth order effects was well and truly debunked. This doesn't disprove the existence of birth order effects, and he makes a decent case. > First, he's taking the results of a voluntary survey of users of his own site And he thoroughly discusses the self-selection bias. > Another example: younger siblings often specifically don't want to go to the same school as their older siblings, so if an older sibling gets into Harvard, they are less likely to bother applying. If first-borns are more likely to go to Harvard, that's a birth order effect too. If they're not more likely to go to Harvard, then Harvard should have an even mix of birth orders and so aren't subject to the bias you point out.

losteverything 9y ago

Few things helped me more understanding people and family than knowledge of birth order. First born, middle, baby, only... Quite helpful as how to understand and predict people's actions. And how to communicate with them. Also, the cases where the first born or first son being expected to behave like a FB but are naturally not...often they dont realize this until adulthood. The book by Leman (The Birth Order Book) i bought shortly after entering the workforce. A great read.

tgb 9y ago

I was taught birth order effects in middle school in the 2000's in the US in a "health" class (in the same unit we also did handwriting analysis). We were literally shown a video of a family in which everyone explained why they were the rebel as the second child, the overachiever as the first child, the spoiled brat as the youngest, etc. Birth order effects might exist... but even if that were true we should not teach them to middle-schoolers as determining their life. This is for the same reason that we would not want a video of a "typical community" showing a white male doctor, a white female kindergarten teacher, and a black male janitor even if all of those occupations are statistically more likely to be held by those demographics than the others. Because we live in a time and a place where children get to choose that they are not like their statistical cohort if they put their mind to it. The only positive thing I took out of that class was the number of other students going "this is bullshit, I'm a first child and am the rebel of the family" or whatever. And it was a good introduction to not trusting authority.

AstralStorm 9y ago
Devil's advocate here: why shouldn't we teach people their position in life is largely predetermined? We have precedent in Confucian and Hinduist philosophies. If it isn't, wouldn't we state so? I am looking for an utilitarian valid and true argument.
- pas 9y ago
  We should teach people about these things that have a great effect on their life trajectory, but maybe, just maybe, middle-schoolers are not ready to appreciate the complex interplay between overlapping Gauss curves, path dependence, self-fulfilling prophecies. Of course people should know where they come from and what does that mean, just as it's usually important to tell kids if they are adopted or have some serious congenital problem. (Usually because it can mean life or death, as we all seen it in [medical] dramas where people search for organ donors and so on.) But the question of when and how to tell is a big one, and there are probably many good answers, but alas probably all of them are forged in hard compromises between hurting the kid now, or letting them finding it out by accident.

canjobear 9y ago

Didn't he also run a control condition on Mechanical Turk? Why isn't that analyzed here to show the effect?

gonational 9y ago

Middle child here. I didn’t like the methodology of this study, so I did my own little study, my wife being the core respondent. The results were astounding and the P value is off the charts (higher is better in this case - trust me). Conclusion: middle children are the best

thrav 9y ago
Has this conclusion ever been called into question?

godelski 9y ago

Anyone else find it strange that the author used SAT scores as a metric for intelligence? I think it is kind of absurd to think that a test that is specifically not designed to test intelligence and designed to give trick or misleading questions is a good metric. Not to say there isn't a decent correlation between intelligence and test scores, but a significant amount of people fall through the cracks. From what I understand, even the academic communities don't place a lot of weight on tests like SAT, ACT, GRE, etc. I think it is fine to use this method to measure intelligence, but not in isolation.

skybrian 9y ago
The survey asked for both SAT and IQ scores, but both questions were optional.
dragonwriter 9y ago
> Anyone else find it strange that the author used SAT scores as a metric for intelligence Since SAT scores are very highly correlated with IQ test scores, and they are often more available, no, not at all. I'm much more concerned with how the sample (if it can even be called that) was generated, which kind of makes the whole thing worthless. The pointers to peer-reviewed studies (even though almost certainly cherry-picked) are more useful than the original “research” reported.
- godelski 9y ago
  Like I said, there is a correlation, but I definitely would not argue that it is "very highly correlated". I found one paper by Frey [1] that discusses a significant correlation, but you will see that it is definitely not the "very highly" that you claim. I only gave a quick glance of the article, but I'm not even sold on its results because their methods suggest they might be over fitting the data (them just trying different fit methods to yield better results feels sketchy. Maybe they back it up better than I saw over the quick glance). That all being said, correlation itself is not a de facto proof nor does it mean it is a good metric. There is a 99.8% correlation (which I'd call "very highly correlated") between US spending on science/space/technology and deaths by strangulation/hanging/suffocation[2]. I think we can all see that it would be laughable to use one as a predictor of the other. Yeah, this example is ludicrous and obvious, but the difficult part is when you expect things to be dependent (which is what we are seeking for a good metric, not correlation), but aren't. It is easy to find data to match the results you are looking for, but that doesn't mean they are good results. [1] https://www.psychologicalscience.org/pdf/ps/Frey.pdf?origin=publication_detail https://www.psychologicalscience.org/pdf/ps/Frey.pdf?origin=... [2] http://www.tylervigen.com/spurious-correlations http://www.tylervigen.com/spurious-correlations

workthrowaway27 9y ago

Wow, I'm impressed that the average IQ of Scott's readership is so high (at least if you use SAT as a proxy for IQ).

ggggtez 9y ago

Not convinced. What about the effect of selection bias? That done probably accounts for the entire "study"

KirinDave 9y ago

> It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. That can’t explain why one group reads this blog so much more often than the other So, uh... People understand that "average difference" is a miserable plan here right?

deleted 9y ago
[deleted]

trgv 9y ago

I thought it was conventional wisdom that sexual orientation in males is influenced by birth order. If that's the case then I'd be surprised if there were no other effects. https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male_sexual_orientation https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male...

Froyoh 9y ago
Huh. First time hearing about this!

JustSomeNobody 9y ago

Anecdata. My older brother was as smart as a box of rocks. Even given that, he was an under achiever. He would couch surf and mooch off anyone. He would work a job until the first pay check then quit. If there was ever a reason to be against UBI, he was it. I would tell my mom he's like that first pancake that just doesn't turn out right because you rushed. I, on the other hand, became an engineer.

dragonwriter 9y ago
I dunno, sounds to me like your brother is the kind of person whose need for money a d resulting intermittent attachment to the labor forces drives down efficiency and wages and, as such, is an argument for UBI rather than against it.

mcguire 9y ago

"I first started thinking this at transhumanist meetups, when it would occasionally come up that everyone there was an oldest child." Alternative hypothesis: first-born children wish to escape their siblings so much that they would prefer to leave the species.

AstralStorm 9y ago
This is not what is being analysed and either conclusion is data dredging.

doku 9y ago

There are some articles on HN about boredom and creativity. Perhaps its just that firstborn have more time alone. It'd be interesting to see age differences vs creativity.

gaius 9y ago

I’ve often thought that certain jobs should only be open to first borns. Jobs with serious responsibilities.