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From the Comments on “Is College Worth It?”

Commenter GP writes:

Great post. Further thoughts:
1. Signalling and the sheepskin effect. It would appear that the importance of college in the US is, to a large extent, the signal given by being admitted to a selective university, and the signal given by successfully completing four years of coursework. This might explain why Goldman Sachs would hire a Harvard anthropology major.
2. I believe I read (proof needed) that the proportion of college enrollments in “soft” fields has been consistently increasing over time. Signalling aside, your major matters for employability. Not to mention basic writing and communication skills, which I found severely lacking in students at a flagship public university in the US.
3. There is indeed evidence that when you enter the job market (boom or recession) can affect your lifetime income. Getting a Master’s degree to delay job market entry until after a recession might be a good move, unless everyone reasons the same way.
4. The discussion is often framed as “yes, college at any cost” vs. “no college is ever worthwhile.” This is absurd. Cost matters, and a simple tool like Net Present Value can help get a ballpark estimate of the value of a particular college degree.
5. Gates, Zuckerberg, Jobs… the media never discuss survivorship bias…

I agree with all points. I have seen many people with non-STEM degrees get jobs in investment banking or in management consulting–not necessarily because they were smarter than others, but because of where they went to college. Continue reading

PSA: p-Values are Thresholds, Not Approximations

A post by Dave Giles reminded me of something important, which I once presumed everyone knew, but which the anecdote I’m about to recount clearly illustrates should be clearly taught to students.

But first, Dave’s post. It is titled “How (Not) to Interpret that p-Value,” links to another, older post where the author lists all the metaphors for coefficients that are not significant, but whose p-value is “close enough” to 0.10 (or 0.05, if you adopt a strict view that the 10 percent significance level is not significant enough). My own preferred expression, which I am sure I have used more than once, is “borderline significant,” but the author lists hundreds (yes, hundreds!) of such metaphors, among which “a considerable trend toward significance,” “approaches but fails to achieve a customary level of statistical significance,” “barely escapes being statistically significant at the 5% risk level,” “fell just short of the traditional definition of statistical significance,” “only slightly missed the conventional threshold of significance,” and so on. Like the author says: A result that is not statistically significant is still not statistically significant, no matter how you talk about it.

p-Values are for Crossing from Above, Not Rounding Down

As for the anecdote, it goes as follows. I was once working with a coauthor and their grad student. Specifically, I was working with the grad student because my coauthor had a meeting that afternoon. The two of us were running some rough-cut regressions, taking a first stab at some data we had just received. As is often the case, we realized we had to cluster our standard errors at the relevant level. So we did that, and the coefficient of interest, which had hitherto been significant, now had a p-value of 0.102 because of the clustering.

That was when the grad student said: “Well it’s significant, but barely.” I asked the grad student to explain their reasoning, because I was curious to see what they saw that I wasn’t seeing. They then said “Well, the p-value rounds down to 0.10, right?” It was then that I had to tell the student that p-values are thresholds, not approximations, and that if a p-value is greater than 0.10, then the estimate is not significant at any of the conventional levels. Likewise, if a p-value is 0.051, the estimate is only significant at the 10 percent level, no matter how you want it to be significant at the 5 percent level. That was something which I thought was common knowledge, but which my interaction with the grad student clearly showed is not necessarily common knowledge.



Interview with Bettina Shell-Duncan, Pioneer of Research on Female Genital Cutting

This past week, the Atlantic published an interview with Bettina Shell-Duncan, an anthropologist and a pioneer of research on female genital cutting. Among interesting excerpts (the emphasis is mine):

So what can foreign activists—as well as locals who oppose female genital cutting—do to curb the practice? For starters, Bettina Shell-Duncan, an anthropology professor at the University of Washington who has been studying the practice in many countries for years, suggests using the term “cutting” rather than “mutilation,” which sounds derogatory and can complicate conversations with those who practice FGC.

This is exactly why Lindsey Novak, Tara Steinmetz, and I decided to refer to the phenomenon as FGC rather than FGM in our paper, nothing in footnote 1 on page 2 that Continue reading