Desislava Petkova writes:

An article in the Family section of the Guardian announced Mothers negatively affected by having three daughters and no sons, study shows. The study is “All we want is a healthy baby – well, and one that is the opposite sex to what we have already.”

I’m not sure their methodology makes sense (though I admit I got suspicious because they end up drawing a subtly misogynistic conclusion.) The authors use two British cohort studies, one cohort of children born in 1958 and the other of children born in 1970. They seem to combine the cohorts for all analyses—even though they mention the importance of “cultural attitudes regarding gender”—so they effectively assume that parents born in 1958 and in 1970 have the same cultural attitudes about gender? Along these lines, it’s not clear what this study has to say about parents nowadays.

One of the most incongruous statements comes in the Discussion. It was also highlighted in the Guardian article and that’s what grabbed my attention in the first place: they seem to say that mothers are jealous of their daughters and it takes them ~10 years to get over it:

The SWB (= subjective well-being) findings are driven entirely by mothers who fail to have a boy after having two girls. (…) In our results it seems that mothers do not want to have too many children of the same sex as them. It is possible this reflects not just an issue of children, but one of household composition, with the mother not wanting too many females in the household.

Even if the analysis shows convincingly that mothers who have a third girl instead of a boy (ie. “lose the birth lottery” in their words) have a decreased subjective well-being for a decade, it’s not clear why they ascribe this to “too many girls” as opposed to “not enough boys.” In fact this interpretation seems to contradict one of their own assumptions: “Secondly, we assume that parents with two children of the same sex want a child of the opposite sex.”

My reply: Yeah, the paper is a disaster, the usual problem of noise mining and storytelling. It’s well written, though!

P.S. In case you’re bothered that Petkova is suspicious of the paper and I concur that it is a disaster, but we give these judgements without a line-by-line reading of the paper, let me just say:

1. I did read the paper; that’s how I formed my judgment.

2. The link is above, and you can feel free to read the paper and form your own judgment. I didn’t write a long post giving all the details because the information is all there for any of you to see. The paper is published; that is, it is public.

3. I don’t think there should be a default attitude that we should believe the claims made in a scientific paper, just because it has been published in a legitimate journal and publicized by a legitimate news outlet. I’m not talking here about fraud or anything like that. I’m just saying that statistics is hard, it’s easy to make mistakes, and often these mistakes are clear to outsiders even though they were not noticed by authors and journal editors. That’s just the way things go. As the saying goes, disbelief does in fact remain an option.

4. I do think that harm is done by the publication and dissemination of bad science, partly because it misleads readers about how the world works, and partly because it encourages wasteful scientific effort in the future. I criticize bad work in this area for the same reason that researchers work in the area in the first place: because I care about social science and because I think it is important.

P.S. Also, read the title of this post carefully. It’s “No, I don’t believe the claim that ‘Mothers negatively affected by having three daughters and no sons, study shows,'” not “No, I don’t believe the claim that ‘Mothers negatively affected by having three daughters and no sons.'” I have no strong opinion on the claim that mothers are negatively affected by having three daughters and no sons. What I object to is the statement that the study shows that claim. Evidence vs. truth.