Daily Data Dump – Thursday

Should you go to an Ivy League School? “Clearly, going to a top-ranked school seems to deliver far higher earnings at age 28 than poorer ranked schools. In fact, the relationship is highly non-linear. Contrary to what you may have heard (“All top-ranked schools are the same”); it in fact looks like the difference between top-ranked Harvard and 9th ranked Dartmouth is on the order of ~$4,000 a year (perhaps $100,000-$200,000 over the course of a lifetime?).”

The Other Social Network. Speaking of non-linearities: “And of course there’s the H-Factor. “I think the name had a lot to do with it,” says Ting. “When we go to a school and say this site is from Columbia, it doesn’t carry the same marketing punch as, This is from Harvard.”

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Mormons are average

Clark of Mormon Metaphysics says below:

My impression is that atheists, Mormons and Jews did best simply because all three groups tend to be well educated. (Someone mentioned stats adjusted for education but I couldn’t see where that was noted although maybe I just missed the obvious)

This is not an unfounded assertion, as it is “common knowledge” in the Zeitgeist that Mormons are high achievers. Ergo, posts such as The Latter Day Ruling Class. There’s one problem here: it’s not really true in a full-throated sense. The sample size for Mormons in the GSS is very small, so that’s not what we need to look at. First, American Religious Identification Survey 2008:


As you can see Mormons have about the average proportion of college graduates for an American ethno-religious group. We can drill-down further with the Religious Landscape Survey. First, comparisons of various religious groups by educational attainment class as proportions:

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The Bushmen are not primitive! (not necessarily)

324_1035_F1To the left is a figure from the 2009 paper The Genetic Structure and History of Africans and African Americans. This paper happens to have excellent coverage of African populations, and the figure is a phylogenetic tree generated from distances between those populations, as well as some non-African ones. I’ve labelled the broad clusters. The Bushmen* branch off first, along with the Pygmies. The other clade represents all other humans, African and non-African. Following the non-Bushmen/Pygmy clade down its branching pattern all non-Africans eventually go their own way, and differentiate into their various groups. South Asians form a clade with Europeans and Middle Easterners. East Asians, Native Americans, and more broadly Oceanians, form their own clade. Outside of Africa you basically have a west vs. east & further east division.

These trees are essential in helping us visualize genetic relationships. Tables of pairwise distances are simply not as informative as representations of the data for the human mind. More colloquially, they blow. Trees and two-dimensional plots are much better representations of the data which we can digest in a more gestalt fashion. We see, therefore we know. Ah, but even the innocent tree can lead a mind astray. Or at least this particular tree. So let’s try something different.

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Should you go to an Ivy League School?

Mark Palko at the excellent blog Observational Epidemiology has a post arguing that the appeal of Ivy League degrees is primarily peer effects and selection. It’s popular these days to sneer at the Ivys. For instance, this WSJ article argues that State schools have an edge in business recruitment.

Still, it’s worth looking at the data. I’ll follow Robin Hanson’s idea that the best place to find an estimate of “X” is to find a paper that looks for “Y”, but controls for X.

There was a study that got a lot of press recently looking at the impact of kindergarden teachers on future economic outcomes. The focus was on how different classroom treatments left long-run impacts, but the slides of the paper also had this interesting result (not found in the actual paper itself):

Clearly, going to a top-ranked school seems to deliver far higher earnings at age 28 than poorer ranked schools. In fact, the relationship is highly non-linear. Contrary to what you may have heard (“All top-ranked schools are the same”); it in fact looks like the difference between top-ranked Harvard and 9th ranked Dartmouth is on the order of ~$4,000 a year (perhaps $100,000-$200,000 over the course of a lifetime?). That difference grows to something like $18,000 over 25th ranked UCLA, per year. However, when one gets down to the 75th ranked school; school rank doesn’t much matter anymore. You’re pulling in ~$43k regardless. In fact, these are likely under-estimates of the value of going to a top school. Many elite graduates are still in graduate studies by age 28, and earnings tend to increase as people hit prime working years.

The pure monetary benefits of going to a top-ranked school (including peer and selection effects) are very substantial; and these benefits rise proportionately with the rank of the school. The marginal benefit of getting into the next highest ranked school is actually higher the higher the rank of your current school. In other words, Yale grads should really really want to go to Harvard. A very rough calculation suggests that everyone who turns down a top-ranked school for a safety to avoid student loans is making a big mistake (though, this is the same type of rough calculation people make when they conclude that there is a high College premium in general).

(Also check out the earnings of those from schools ranked 75 and lower. High school graduates can make perhaps ~$30k a year. So those guys just gave up ~$120k in earnings, plus paying College tuition, for the privilege of making ~$44k by age 28. How big is that College premium again?)

Of course, the large effects of going to a top-ranked school could be coming purely from those peer and selection effects. Another paper, by Krueger and Dale, tackles these issues. They have data on people accepted to both selective and non-selective schools. By tracing the incomes of people who were accepted at both Harvard and Mass U, but choose Harvard against those were accepted at both but choose Mass U; they are able to better parcel out what going to Harvard has on your earnings, as opposed to just being the type of person who can get into Harvard.

If you check out their working paper (these results do not appear in subsequent versions of the paper and media reports), they find that the “Selectivity” of the College you finally go to as judged by Barrons matters a great deal in explaining the variance of future income, though the average SAT of the school does not.

One simple interpretation is that peer and selection effects don’t matter as much as you think. Just being the type of person who can get to Harvard isn’t enough; you need to actually go to Harvard to get the bonus. And having lots of high-SAT score friends at College doesn’t seem to help (though, interestingly, the Kindergarden study above did find evidence of peer effects. Your kindergarden pals matter but your College roommate doesn’t for your future earnings?).

Rather — it’s selectivity that delivers the extra premium, consistent with the findings above. Something about actually going to an Ivy League school — the connections, the signal — imparts the sizable bonus. Potentially, they could even be learning more, but I think we all know that’s not true.

I don’t want to push on this too much. Obviously, the type of person accepted to both Harvard and Mass U, but goes to Harvard, is going to be different from the person who chose Mass U in the same situation. And SAT scores don’t constitute the full universe of peer effects. Arguably, going to a highly selective school where everyone was able to pass through a very tough selection process produces a peer effect stronger than simply going to a school of lazy smart people.

But certainly I think this research points to strong and durable rents being earned by graduates of elite Universities. I think that makes Admissions processes that focus so strongly on legacy identity so pernicious. If Dan Ariely is really concerned about inequality, perhaps he should complain more about his University’s (Harvard) Admissions processes. There is perhaps no force There are few forces in the country so strongly promotive of inter-generational wealth accumulation as College Admissions practices, particularly at the top end of the wealth distribution, yet they remain very under-discussed whenever these topics come up.

A world almost built

By now you’ve probably seen headlines such as A Habitable Exoplanet — for Real This Time. Phil Plait has a more sober assessment. Still, he concludes:

But perhaps the most interesting and exciting aspect of all this is what it implies. The Milky Way galaxy is composed of about 200 billion stars, and is 100,000 light years across. The fact that we found a planet that is even anything like the Earth at all orbiting another star only 20 light years away makes me extremely optimistic that earthlike planets are everywhere in our galaxy. 20 light years is practically in our lap compared to the vast size of our galaxy, so statistically speaking, it seems very likely it’s not unique. I don’t want to extrapolate from a data set of two (us and them), but if this is typical, there could be millions of such planets in the galaxy. Millions.

So we don’t know if this planet is all that much like Earth — the surface gravity may be quite high if it’s dense and small, for example, or it may not have any air, or it may have a thick atmosphere like Venus — but what it’s telling us is that smaller, lower mass planets at the right distance from their star for liquid water are almost certainly common in the galaxy.

I assume this means we can play around with the Drake equation? In any case, I am now reminded of Poul Anderson’s essay “The creation of imaginary worlds: the world builder’s handbook and pocket companion.” You can read most of the essay online at Google Books. Or, find it in . For us “squishy science” lovers the biochemist Hal Clament has an essay which follow’s Anderson’s which outlines how to create imaginary life.

Daily Data Dump – Wednesday

A Widespread Chromosomal Inversion Polymorphism Contributes to a Major Life-History Transition, Local Adaptation, and Reproductive Isolation. Edmund Yong has already written this paper up. Sheril Kirshenbaum offers up her thoughts, stimulated by personal communication with the first author.

Inferring the Dynamics of Diversification: A Coalescent Approach. The title is more forbidding than the topic: “Applying our approach to a diverse set of empirical phylogenies, we demonstrate that speciation rates have decayed over time, suggesting ecological constraints to diversification. Nonetheless, we find that diversity is still expanding at present, suggesting either that these ecological constraints do not impose an upper limit to diversity or that this upper limit has not yet been reached.”

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Every variant with an author!

I recall projections in the early 2000s that 25% of the American population would be employed as systems administrators circa 2020 if rates of employment growth at that time were extrapolated. Obviously the projections weren’t taken too seriously, and the pieces were generally making fun of the idea that IT would reduce labor inputs and increase productivity. I thought back to those earlier articles when I saw a new letter in Nature in my RSS feed this morning, Hundreds of variants clustered in genomic loci and biological pathways affect human height:

Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits1, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait2, 3. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.

The supplements run to nearly 100 pages, and the author list is enormous. But at least the supplements are free to all, so you should check them out. There are a few sections of the paper proper that are worth passing on though if you can’t get beyond the paywall.

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Religious illiteracy is the norm

By now you probably know that:

Atheists and agnostics, Jews and Mormons are among the highest-scoring groups on a new survey of religious knowledge, outperforming evangelical Protestants, mainline Protestants and Catholics on questions about the core teachings, history and leading figures of major world religions.

On average, Americans correctly answer 16 of the 32 religious knowledge questions on the survey by the Pew Research Center’s Forum on Religion & Public Life. Atheists and agnostics average 20.9 correct answers. Jews and Mormons do about as well, averaging 20.5 and 20.3 correct answers, respectively. Protestants as a whole average 16 correct answers; Catholics as a whole, 14.7. Atheists and agnostics, Jews and Mormons perform better than other groups on the survey even after controlling for differing levels of education.

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To gain pallor is easier than losing it


John Hawks illustrates what can be gained at the intersection of old data and analysis and new knowledge, Quote: Boyd on New World pigmentation clines:

I’m using some statistics out of William Boyd’s 1956 printing of Genetics and the Races of Man[1]. It gives a good accounting of blood group data known more than fifty years ago, which I’m using to illustrate my intro lectures. Meanwhile, there are some interesting passages, from the standpoint of today’s knowledge of the human genome and its variation.

On skin pigmentation — this is the earliest statement I’ve run across of the argument that the New World pigmentation cline is shallower than the Old World cline because of the relative recency of occupation….

Looking at what was said about pigmentation generations ago is of interest because it’s a trait which in many ways we have pegged. See Molecular genetics of human pigmentation diversity. Why humans vary in pigmentation in a deep ultimate sense is still an issue of some contention, but how they do so, and when the differences came about, are questions which are now modestly well understood. We know most of the genetic variants which produce between population variation. We also know that East and West Eurasians seem to have been subject to independent depigmentation events. We also know that some of the depigmentation was relatively recent, probably after the Last Glacial Maximum, and possibly as late as the advent of agriculture.

On the New World cline, which is clearly shallower than that of the Old World. The chart below from Signatures of positive selection in genes associated with human skin pigmentation as revealed from analyses of single nucleotide polymorphisms is useful:

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Daily Data Dump – Tuesday

Just a minor note: if you want an admin update on this weblog, go to my . You don’t need to subscribe, as you might not be interested in all my random interactions with other bloggers. But if I don’t post for a few days, please don’t email me or post a comment in the thread wondering if I’m well, just check the . Easier that way not to clutter up the content on this website. You can always find the link to twitter right under my head shot on the sidebar. You can’t miss it.

Getting even with the odds ratio. To some extent it’s “common sense,” context matters. But nice to be reminded. Especially when in some cases context doesn’t matter.

Complexity Not So Costly After All: Moderately Complex Plants and Animals Can Be Better Equipped to Adapt. “By incorporating a more realistic representation of pleiotropy, Zhang’s analysis found the reverse of Orr’s arguments to be true. Although Fisher’s observation still holds, reversing Orr’s assertions minimizes its impact, thus reducing the cost of complexity.” I plan on blogging this, so I won’t say more.

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