Sunday, June 12, 2016

WHAAT?  Premature babies are brighter??

When I first saw the findings below I thought I was looking at another example of researchers getting their statistics back to front.  The logical and conventional view is that premature birth harms the baby to some degree.  And that is the official medical view too.  The authors of the study below were obviously pretty perturbed by their results too and turned themselves inside out trying to think of ways in which their very strong study got it wrong.  And I think that they went close to isolating the problem, but did not have the psychometric background needed to get it exactly right

The thing that told me what was going on was the Dutch Famine Study.  In the closing phase of WW2, Nederland experienced a severe food shortage.  The mothers of babies born at that time did the best for their infants but a lot still went very hungry.  But a food shortage at that early age could be expected to handicap the infant to some degree, with brain damage being probable.  So when that birth cohort came up for conscription into the Dutch army 18 years later, there was great interest in what their average IQs would be.  Most armies do carry out ability testing as an aid to weeding out soldiers who would be more dangerous to their companions than to the enemy. Putting lethal weapons into the hands of dummies is not recommended.

So what did the Dutch psychologists discover?  Did they find that the average IQ for that year was low?  No. To the contrary, they found that the average IQ was unusually HIGH for that year. 

So what had happened?  It was a eugenic effect.  As has repeatedly been shown, high IQ is a marker of general biological fitness -- and only the fit babies survived the famine.  The less fit were weeded out -- died.  So only the fit survived and they had higher IQs than average.

So you might by now see the strong analogy with the results below.  Less fit babies did not survive pre-term birth.  Those who did survive were generally  more fit biologically and hence of higher IQ.  It's actually interesting confirmation of the Dutch findings.  The other finding below, of a slight probability of physical impairment probably shows that even a selection effect cannot cancel out all the stresses and disadvantages that pre-term birth must be expected to impose

Long-term Cognitive and Health Outcomes of School-Aged Children Who Were Born Late-Term vs Full-Term

David N. Figlio et al.


Importance: Late-term gestation (defined as the 41st week of pregnancy) is associated with increased risk of perinatal health complications. It is not known to what extent late-term gestation is associated with long-term cognitive and physical outcomes. Information about long-term outcomes may influence physician and patient decisions regarding optimal pregnancy length.

Objective: To compare the cognitive and physical outcomes of school-aged children who were born full term or late term.

Design, Setting, and Participants:  We analyzed Florida birth certificates from 1994 to 2002 linked to Florida public school records from 1998 to 2013 and found 1?442?590 singleton births with 37 to 41 weeks' gestation in the Florida Bureau of Vital Statistics. Of these, 1?153?716 children (80.0%) were subsequently located in Florida public schools. Linear and logistic regression models were used to assess the association of gestational age with cognitive and physical outcomes at school age. Data analysis took place between April 2013 and January 2016.

Exposures: Late-term (born at 41 weeks) vs full-term (born at 39 or 40 weeks) gestation.

Main Outcomes and Measures:  There were a number of measures used, including the average Florida Comprehensive Assessment Test mathematics and reading scores at ages 8 through 15 years; whether a child was classified as gifted, defined as a student with superior intellectual development and capable of high performance; poor cognitive outcome, defined as a child scoring in the fifth percentile of test takers or having a disability that exempted him or her from taking the Florida Comprehensive Assessment Test; and Exceptional Student Education placement owing to orthopedic, speech, or sensory impairment or being hospitalbound or homebound.

Results:  Of 1 536 482 children born in Florida from singleton births from 1994 to 2002 with complete demographic information, 787 105 (51.2%) were male; 338 894 (22.1%) of mothers were black and 999 684 (65.1%) were married at time of birth, and the mean (SD) age for mothers at time of birth was 27.2 (6.2) years. Late-term infants had 0.7% of an SD (95% CI, 0.001-0.013; P = .02) higher average test scores in elementary and middle school, 2.8% (95% CI, 0.4-5.2; P = .02) higher probability of being gifted, and 3.1% (95% CI, 0.0-6.1; P = .05) reduced probability of poor cognitive outcomes compared with full-term infants. These cognitive benefits appeared strongest for children with disadvantaged family background characteristics. Late-term infants were also 2.1% (95% CI, −0.3 to 4.5; P = .08) more likely to be physically impaired.

Conclusions and Relevance: There appears to be a tradeoff between cognitive and physical outcomes associated with late-term gestation. Children born late-term performed better on 3 measures of school-based cognitive functioning but worse on 1 measure of physical functioning relative to children born full term. Our findings provide longer-run information for expectant parents and physicians who are considering delivery at full term vs late term. These findings are most relevant to uncomplicated, low-risk pregnancies.


Thursday, June 9, 2016

How to study IQ when you are not studying IQ

The article below is a significant advance.  The authors bypass IQ tests and go straight to the genes behind it.  They show that a particular set of genes can give you the same sort of correlates as you get with IQ tests.  Once again smart people are shown to be advantaged in all sorts of ways. 

The work is still at an early stage, however, as the correlations were much weaker than are found with IQ tests, indicating that only some of the relevant genes have so far been found and suggesting that some of the genes used were statistical "noise".   

There are by now a few comments about the study online, all of which are remarkably tight-assed.  They do their best to play  the findings down.  Put in the context of previous IQ studies, however, the findings are powerfully confirmatory of the pervasive importance of IQ -- vastly unpopular though that fact may be

The final sentence below is sheer nonsense -- added for the sake of political correctness only.

The Genetics of Success: How Single-Nucleotide Polymorphisms Associated With Educational Attainment Relate to Life-Course Development

Daniel W. Belsky et al.


A previous genome-wide association study (GWAS) of more than 100,000 individuals identified molecular-genetic predictors of educational attainment. We undertook in-depth life-course investigation of the polygenic score derived from this GWAS using the four-decade Dunedin Study (N = 918). There were five main findings. First, polygenic scores predicted adult economic outcomes even after accounting for educational attainments. Second, genes and environments were correlated: Children with higher polygenic scores were born into better-off homes. Third, children’s polygenic scores predicted their adult outcomes even when analyses accounted for their social-class origins; social-mobility analysis showed that children with higher polygenic scores were more upwardly mobile than children with lower scores. Fourth, polygenic scores predicted behavior across the life course, from early acquisition of speech and reading skills through geographic mobility and mate choice and on to financial planning for retirement. Fifth, polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill. Effect sizes were small. Factors connecting DNA sequence with life outcomes may provide targets for interventions to promote population-wide positive development.

Psychological Science June 1, 2016.  doi: 10.1177/0956797616643070

Wednesday, June 1, 2016

There is still good social and economic upward mobility in America

Jeff Jacoby's argument below is both a cheery one and mostly right. He seems unaware, however, that the Italian study he mentions has a large predecessor in the work of Gregory Clark, who also finds that wealth is to a significant extent dynastic.

Clark's findings that SOME lineages stay wealthy is an interesting one.  And he explains it well.  He says (to simplify a little) that what is inherited is not wealth but IQ.  As Charles Murray showed some years back, smarter people tend to be richer and tend to marry other smart people.  So their descendants stay smart and smart people are mostly smart about money too.

But Clark's findings do not in fact diminish any of the points Jacoby makes.  Dynasties of wealth do exist but most people's wealth or poverty is not dynastic

TWO RESEARCHERS AT the Bank of Italy have documented something remarkable about Florence, the gorgeous Tuscan capital where the Medicis ruled and the Renaissance was born: The city’s wealthiest residents today are descended from its wealthiest families six centuries ago.

As The Wall Street Journal reported this month, economists Guglielmo Barone and Sauro Mocetti looked at tax records compiled in Florence in 1427 alongside municipal tax data from 2011. “Because Italian surnames are highly regional and distinctive,” the Journal explained, “they could compare the income of families with a certain surname today, to those with the same surname in 1427.” What they found was that the wealthiest names in 21st-century Florence belong to families that were near the top of the socioeconomic hierarchy in 15th-century Florence — those who were lawyers, or who belonged to the wool, silk, and shoemaker guilds.

Barone and Mocetti did not identify the actual families listed in the Florentine tax rolls, but they note that about 900 of the surnames are still used in Florence by some 52,000 taxpayers. Not all of them are descended from those who bore those names in 1427, of course. And the new study appears to focus primarily on correlations among the very highest and lowest income-earners, not on the majority in between. Over the course of six centuries, the authors note, Florence has undergone “huge political, demographic, and economic upheavals,” and they acknowledge that intergenerational mobility is higher in Italy today than was the case before the 20th century.

Yet even with all those caveats, the persistence of economic and social status across 600 years of Florentine history is eye-opening. And it helps explain what impelled myriads of Italians to uproot their lives and relocate to new homes — especially the 5 million people who immigrated to the United States between 1876 and 1930.

Critics have been lamenting the death of the American Dream for decades, but the US remains what it has always been: a land of opportunity where neither poverty nor wealth is immutable, and no one’s station in life is fixed at birth. Politicians whip up economic envy; activists stoke resentment at a “rigged” system. And yet economic mobility is alive and well in America, which is why so many foreigners still stream to our shores.

Ample evidence bears this out, much of it gathered in long-term studies that track the earnings of large blocs of Americans over many years.

In 2012, the Pew Charitable Trusts published one such study, appropriately titled “Pursuing the American Dream.” Drawing on longitudinal data spanning four decades, Pew was able to show that the vast majority of Americans have higher family incomes than their parents did. Among US citizens who were born into families at the lowest rung of the economic ladder — the bottom one-fifth of income-earners — a hefty 57 percent had moved into a higher quintile by adulthood. In fact, 4 percent had risen all the way to the highest quintile. Over the same period, 8 percent of those born into the highest income category had dropped all the way to the bottom.

For a different examination into economic mobility, analysts at the Treasury Department studied 84 million federal returns of taxpayers who had taxable income in both 1996 and 2005. They, too, found that “roughly half of taxpayers who began in the bottom income quintile moved up to a higher income group.” For two-thirds of all taxpayers, real incomes had increased. And — repudiating the frequent lament that upward mobility is vanishing from American life — the Treasury study concluded that the “degree of mobility among income groups [was] unchanged from the prior decade.”

The 25th great-grandsons of medieval Florentine shoemakers may still be riding high, but things don’t work that way in America. Here, riches-to-rags stories are not uncommon. When Bhashkar Mazumder, an economist at the Federal Reserve Bank of Chicago, examined the earnings of thousands of men born between 1963 and 1968, he discovered that 17 percent of those whose fathers were in the top 10th of the income scale had dropped to the bottom third by the time they were in their late 20s or early 30s. Movement between income groups over the course of a lifetime is the norm for most Americans. The rich often get richer, but plenty of them get poorer, too. Though the top 1 percent makes a popular target, it’s actually a group no one stays in for very long. On the other hand, it’s a group that 11 percent of Americans will reach at some point during their working lives.

Affluence in America is dynamic, and our economic system is biased toward success. But bias isn’t a guarantee. Mobility — up and down — depends to a great degree on the choices that people make for themselves. Individuals who finish high school, marry before having children, don’t engage in criminal activity, and work diligently have a very high likelihood of achieving success. Those who don’t, don’t.

Of course, there are impediments to mobility that are beyond the control of any individual, and that are most likely to hurt those who start out in America’s poorest precincts. Broken public schools, for example. The normalization of single-parent households. Too-easy access to welfare benefits. Counterproductive mandates, like minimum-wage laws and stifling licensing rules. Would that our political demagogues and professional populists put as much effort into dismantling those barriers as they do into demonizing the rich and yapping about inequality.

Yappers notwithstanding, the American Dream is far from dead. This isn’t Florence. No one is locked out of economic success today because of their ancestors’ status long ago. America remains the land of opportunity. Make the most of it.