Results for “cohort”
215 found

The rise of the temporary scientist

Here is a new and important piece on the economics of science, from Staša MilojevićFilippo Radicchi, and John P. Walsh:

Contemporary science has been characterized by an exponential growth in publications and a rise of team science. At the same time, there has been an increase in the number of awarded PhD degrees, which has not been accompanied by a similar expansion in the number of academic positions. In such a competitive environment, an important measure of academic success is the ability to maintain a long active career in science. In this paper, we study workforce trends in three scientific disciplines over half a century. We find dramatic shortening of careers of scientists across all three disciplines. The time over which half of the cohort has left the field has shortened from 35 y in the 1960s to only 5 y in the 2010s. In addition, we find a rapid rise (from 25 to 60% since the 1960s) of a group of scientists who spend their entire career only as supporting authors without having led a publication. Altogether, the fraction of entering researchers who achieve full careers has diminished, while the class of temporary scientists has escalated. We provide an interpretation of our empirical results in terms of a survival model from which we infer potential factors of success in scientific career survivability. Cohort attrition can be successfully modeled by a relatively simple hazard probability function. Although we find statistically significant trends between survivability and an author’s early productivity, neither productivity nor the citation impact of early work or the level of initial collaboration can serve as a reliable predictor of ultimate survivability.

As Raghuveer Parthasarathy argues in his excellent blog post: “…small groups may be innovative, but they are the hardest to sustain given the randomness of scientific funding.”

For the pointer I thank Raghuveer Parthasarathy.

The Brother Earnings Penalty

This paper examines the impact of sibling gender on adolescent experiences and adult labor market outcomes for a recent cohort of U.S. women. We document an earnings penalty from the presence of a younger brother (relative to a younger sister), finding that a next-youngest brother reduces adult earnings by about 7 percent. Using rich data on parent-child interactions, parents’ expectations, disruptive behaviors, and adult outcomes, we provide a first step at examining the mechanisms behind this result. We find that brothers reduce parents’ expectations and school monitoring of female children while also increasing females’ propensity to engage in more traditionally feminine tasks. These factors help explain a portion of the labor market penalty from brothers.

That is by Angela Cooks and Eleonora Patacchin in Labour Economics.  Once again, family niche effects seem to matter.  Via the excellent Kevin Lewis.

Why do so many academics dislike the market?

It seems Nozick was right after all, here is Raul Magni-Berton and Diego Rios:

In this article, the authors explore why academics tend to oppose the market. To this intent the article uses normative political theory as an explanatory mechanism, starting with a conjecture originally suggested by Robert Nozick. Academics are over-represented amongst the best students of their cohort. School achievement engenders high expectations about future economic prospects. Yet markets are only contingently sensitive to school achievement. This misalignment between schools and markets is perceived by academics – and arguably by intellectuals in general – as morally unacceptable. To test this explanation, the article uses an online questionnaire with close to 1500 French academic respondents. The data resulting from this investigation lend support to Nozick’s hypothesis.

Via Rolf Degen.

Best non-fiction books of 2018

First let me start with three books from my immediate cohort, which I will keep separate from the rest:

Kevin Simler and Robin Hanson, The Elephant in the Brain: Hidden Motives in Everyday Life.

Bryan Caplan, The Case Against Education.

Tyler Cowen, Stubborn Attachments: A Vision for a Society of Free, Prosperous, and Responsible Individuals.

All of those are wonderful, but Stubborn Attachments is the best of the three.  Otherwise, we have the following, noting that the link often contains my longer review.  These are in the order I read them, not by any other kind of priority.  Here goes:

Varun Sivaram’s Taming the Sun: Innovations to Harness Solar Energy and Power the Planet.

Nassim Taleb, Skin in the Game.

Charles C. Mann, The Wizard and the Prophet: Two Remarkable Scientists and Dueling Visions to Shape Tomorrow’s World.

Quinn Slobodian, Globalists: The End of Empire and the Birth of Neoliberalism.

Cecilia Heyes, Cognitive Gadgets: The Cultural Evolution of Thinking.

David Reich, Who We Are and How We Got Here.

Nick Chater, The Mind is Flat: The Illusion of Mental Depth and the Improvised Mind.

Allen C. Guelzo, Reconstruction: A Concise History.

Emily Dufton, Grass Roots: The Rise and Fall and Rise of Marijuana in America.

Philip Dwyer, Napoleon: Passion, Death, and Resurrection, 1815-1849.

David Olusoga, Black and British: A Forgotten History.

David Edgerton, The Rise and Fall of the British Nation: A Twentieth Century History.

Francesca Lidia Viano’s Sentinel: The Unlikely Origins of the Statue of Liberty.

W.J. Rorabaugh, Prohibition: A Concise History.

Victor Sebestyen, Lenin: The Man, the Dictator, and the Master of Terror.

Porochista Khakpour, Sick: A Memoir.

M. Mitchell Waldrop, The Dream Machine: J.C.R. Licklider and the revolution that made computing personal.

David W. Blight, Frederick Douglass: Prophet of Freedom.

Martin Gurri, The Revolt of the Public and the Crisis of Authority in the New Millennium.

There are also books which I think very likely deserve to make this list, but I have not had time to read much of them.  Most notably, those include the new biographies of Alain Locke, Thomas Cromwell, Gandhi, and Winston Churchill.

Overall I thought this was a remarkably strong year for intelligent non-fiction.  And as always, I have forgotten some splendid books — usually it is yours.  Sorry!

The best results on assortative mating and inequality I have seen

This paper studies the evolution of assortative mating in the permanent wage (the individual-specific component of wage) in the U.S., its role in the increase in family wage inequality, and the factors behind this evolution. I first document a substantial trend in assortative mating, as measured by the permanent wage correlation of couples, from 0.3 for families formed in the late 1960s to 0.52 for families formed in the late 1980s. I show that this trend accounts for more than one-third of the increase in family wage inequality across these cohorts of families. I then argue that the increase in marriage age across these cohorts contributed to the assortative mating and thus to the rising inequality. Individuals face a large degree of uncertainty about their permanent wages early in their careers. If they marry early, as most individuals in the late 1960s did, this uncertainty leads to weak marital sorting along permanent wage. But when marriage is delayed, as in the late 1980s, the sorting becomes stronger due to the quick resolution of this uncertainty with work experience. After providing reduced-form evidence on the impact of marriage age, I build and estimate a marriage model with wage uncertainty and show that the increase in marriage age can explain almost 80% of the increase in assortative mating.

That is from the job market paper of Alparslan Tuncay, from the University of Chicago.

The philosophy and practicality of Emergent Ventures

Let’s start with some possible institutional failures in mainstream philanthropy.  Many foundations have large staffs, and so a proposal must go through several layers of approval before it can receive support or even reach the desk of the final decision-maker.  Too many vetoes are possible, which means relatively conservative, consensus-oriented proposals emerge at the end of the process.  Furthermore, each layer of approval is enmeshed in an agency game, further cementing the conservatism.  It is not usually career-enhancing to advance a risky or controversial proposal to one’s superiors.

There is yet another bias: the high fixed costs of processing any request discriminate against very small proposals, which either are not worthwhile to approve or they are never submitted in the first place.

Finally, foundations often become captured by their staffs.  The leaders become fond of their staffs, try to keep them in the jobs, regard the staff members as a big part of their audience, and adopt the perspectives of their staffs, more so as time passes.  That encourages conservatism all the more, because the foundation leaders do not want their staffs to go away, and so they act to preserve financial and reputational capital.

To restate those biases:

  1. Too much conservatism
  2. Too few very small grants
  3. Too much influence for staff

So how might those biases be remedied?

Why not experiment with only a single layer of no?

Have a single individual say yes or no on each proposal — final word, voila!  Of course that individual can use referees and conferees as he or she sees fit.

The single judge could be an expert in some of the relevant subject areas of the proposals (that is sometimes the case in foundations, but even then the expertise of the foundation evaluators can decay).

This arrangement also can promise donors 100% transmission of their money to recipients, or close to that.  If someone gives $1 million to the fund, the award winners receive the full $1 million.  This is rare in non-profits.  (In the case of Emergent Ventures there are unbudgeted time costs for me and my assistant, who prints out the proposals, and the paper costs of the printing get charged to general operating expenses at Mercatus.  Still, a $1 million grant at the margin leads to $1 million in actual awards.  I am not paid to do this.)

The solo evaluator — if he or she has the right skills of temperament and judgment — can take risks with the proposals, unencumbered by the need to cover fixed costs and keep “the foundation” up and running.  Think of it as a “pop-up foundation,” akin to a pop-up restaurant, and you know who is the chef in the kitchen.  It is analogous to a Singaporean food stall, namely with low fixed costs, small staff, and the chef’s ability to impose his or her own vision on the food.

Once a fixed sum of money is given away, and the mission of the project (beneficial social change) has been furthered, “the foundation” goes away.  No one is laid off.  Rather than crying over a vanquished institutional empire and laid off friends/co-workers, the solo evaluator in fact has a chance to get back to personally profitable work.  It was “lean and mean” all along, except it wasn’t mean.

The risk-taking in grant decisions is consistent with the incentives of the evaluator, consistent with the level of staffing (zero), and consistent with the means of the evaluator.  A solo evaluator, no matter how talented, does not have the resources to make and tie down multiple demands for complex deliverables.  Rather, a solo evaluator is likely to think (or not) — “hmm…there is some potential in this one.”  The wise solo evaluator is likely to look for projects that have real upside through realizing the autonomous visions of their self-starting creators, rather than projects that appear bureaucratically perfect.

And how about the incentives of the solo evaluator?  Well, a fixed amount of time is being given up, so what is the point in making safe, consensus selections with the awards?  The solo evaluator, in addition to pursuing the mission of the fund, will tend to seek out grants that will boost his or her reputation as a finder of talent.  You might worry that an evaluator, even if fully honest will self-deceive somewhat, and use some of these grants to promote his or her own interests.  I would say donate your money to an evaluator who you are happy to see rise in status.

In other words, the basic vision of Emergent Ventures, the incentives, and its means are all pretty consistent.

The solo evaluator also has the power to make very small grants, simply by issuing a decision in their favor at very low fixed cost.  Alchian and Allen theorem!  That helps remedy the bias against small grants in the broader foundation world.

The single evaluator of course is going to make some mistakes, but so do foundations.  And the costs of these evaluator mistakes have to be weighed against the other upsides of this method.

In my view, at least two percent of philanthropy should be run this way, and right now in the foundation world it is about zero percent.  So I am trying to change this at the margin.

How does this idea scale?  What if it worked really well?  How would we do more of it?

Well, it is not practical for this solo evaluator to handle a larger and larger portfolio of grant requests.  Even if he or she were so inclined, that would bring us back to the problems of institutionalized foundations.  The ideal scaling is that other, competing “chefs” set up their own pop-up foundations.  Imagine a philanthropic world where, next year, you could give a million dollars to the Steven Pinker pop-up, to the Jhumpa Lahiri pop-up, to the Jordan Peterson intellectual venture fund, and so on.  Three years later, you would have an entirely different choice, say intellectual venture funds from Ezra Klein, David Brooks, and Skip Gates, among others.  The evaluators either could donate some of their time, as I am doing, or charge a fee for performing this service.  You also could imagine a major foundation carving off a separate section of their activities, and running this experiment on their own, with an evaluator of their choosing.

In a subsequent post, I will discuss how this model relates to the classical age of patronage running through the Renaissance, into the 18th century, and often into the 20th century as well, often through the medium of individual giving.  I also will consider how this relates to classic venture capital and the relevant economics behind “deal flow.”

In the meantime, I am repeating the list of the first cohort of Emergent Ventures winners.  That link also directs you to relevant background if Emergent Ventures is new to you.

Do female department chairs matter?

Appointing female managers is a common proposal to improve women’s representation and outcomes in the workplace, but it is unclear how well such policies accomplish these goals. Using newly-collected panel data on academic departments, I exploit variation in the timing of transitions between department chairs of different genders with a difference-in-differences research design. For faculty, I find female department chairs reduce gender gaps in publications and tenure for assistant professors and shrink the gender pay gap. Replacing a male chair with a female chair increases the number of female students among incoming graduate cohorts by ten percent with no evidence of a change in ability correlates for the average student.

That is from a new paper by Andrew Langan, who is a job market candidate from Princeton this year.  He has another paper with Leah Boustan, here is an excerpt from the abstract:

We find that schools with better outcomes for women also hire more women faculty, facilitate advisor-student contact, provide collegial research seminars, and are notable for senior faculty with awareness of gender issues.

In yet another piece he estimates the value of unpaid cooking time in Mexico, always higher than you think I would say.

Crack cocaine as a cause of violence

Crack cocaine markets were associated with substantial increases in violence in the U.S. during the 1980s and 1990s. Using cross-city variation in the emergence of these markets, we show that the resulting violence has important long-term implications for understanding current levels of murder rates by age, sex and race. We estimate that the murder rate of young black males doubled soon after crack’s entrance into a city, and that these rates were still 70 percent higher 17 years after crack’s arrival. We document the role of increased gun possession as a mechanism for this increase. Following previous work, we show that the fraction of suicides by firearms is a good proxy for gun availability and that this variable among young black males follows a similar trajectory to murder rates. Access to guns by young black males explains their elevated murder rates today compared to older cohorts. The long run effects of this increase in violence are large. We attribute nearly eight percent of the murders in 2000 to the long-run effects of the emergence of crack markets. Elevated murder rates for younger black males continue through to today and can explain approximately one tenth of the gap in life expectancy between black and white males.

That is from William N. Evans, Craig Garthwaite, and Timothy J. Moore.

The Long-run Effects of Teacher Collective Bargaining

By Michael Lovenheim and Alexander Willén:

Teacher collective bargaining is a highly debated feature of the education system in the US. This paper presents the first analysis of the effect of teacher collective bargaining laws on long-run labor market and educational attainment outcomes, exploiting the timing of passage of duty-tobargain laws across cohorts within states and across states over time. Using American Community Survey data linked to each respondent’s state of birth, we examine labor market outcomes and educational attainment for 35-49 year olds, separately by gender. We find robust evidence that exposure to teacher collective bargaining laws worsens the future labor market outcomes of men: in the first 10 years after passage of a duty-to-bargain law, male earnings decline by $2,134 (or 3.93%) per year and hours worked decrease by 0.42 hours per week. The earnings estimates for men indicate that teacher collective bargaining reduces earnings by $213.8 billion in the US annually. We also find evidence of lower male employment rates, which is driven by lower labor force participation. Exposure to collective bargaining laws leads to reductions in the skill levels of the occupations into which male workers sort as well. Effects are largest among black and Hispanic men. Estimates among women are often confounded by secular trend variation, though we do find suggestive evidence of negative impacts among nonwhite women. Using data from the 1979 National Longitudinal Survey of Youth, we demonstrate that collective bargaining laws lead to reductions in measured non-cognitive skills among young men.

Here is the NBER link, via Matt Yglesias.

Is the reversal of the Flynn Effect environmental?

Maybe so, says a new paper by Bernt Bratsberg and Ole Rogeberg:

Using administrative register data with information on family relationships and cognitive ability for three decades of Norwegian male birth cohorts, we show that the increase, turning point, and decline of the Flynn effect can be recovered from within-family variation in intelligence scores. This establishes that the large changes in average cohort intelligence reflect environmental factors and not changing composition of parents, which in turn rules out several prominent hypotheses for retrograde Flynn effects.

In short, IQ relates inversely to sibling order, and the basic effect is not being generated by a changing composition of married pairs over time.

In other words, we have started building a more stupidity-inducing environment.  Or at least the Norwegians have.  But of course the retrograde Flynn Effect is starting to pop up in the data more generally, and not just in Norway.  From The Times of London:

The IQ scores of young people have begun to fall after rising steadily since the Second World War, according to the first authoritative study of the phenomenon.

The decline, which is equivalent to at least seven points per generation, is thought to have started with the cohort born in 1975, who reached adulthood in the early Nineties.

Have a nice day!

For the pointer I thank Michelle Dawson.

Assorted Thursday links

1. Why did Bitcoin take so long?  And is it ugly?

2. Cashless restaurants in NYC (NYT).

3. “...infants who look like their father at birth are healthier one year later. The reason is such father–child resemblance induces a father to spend more time engaged in positive parenting.”  If looks could kill…

4. Are wealthier millionaires happier?

5. “Therefore the expected years of life lost for a single birth cohort due to the changes in death rates from 2015 to 2016 was larger than the years of life lost by Americans in the Iraq war.

6. Does faculty tweeting help the reputation of universities?

The Flynn effect in reverse does the rot start at the top?

The IQ gains of the 20th century have faltered. Losses in Nordic nations after 1995 average at 6.85 IQ points when projected over thirty years. On Piagetian tests, Britain shows decimation among high scorers on three tests and overall losses on one. The US sustained its historic gain (0.3 points per year) through 2014. The Netherlands shows no change in preschoolers, mild losses at high school, and possible gains by adults. Australia and France offer weak evidence of losses at school and by adults respectively. German speakers show verbal gains and spatial losses among adults. South Korea, a latecomer to industrialization, is gaining at twice the historic US rate.

When a later cohort is compared to an earlier cohort, IQ trends vary dramatically by age. Piagetian trends indicate that a decimation of top scores may be accompanied by gains in cognitive ability below the median. They also reveal the existence of factors that have an atypical impact at high levels of cognitive competence. Scandinavian data from conventional tests confirm the decimation of top scorers but not factors of atypical impact. Piagetian tests may be more sensitive to detecting this phenomenon.

That is newly published research from James R. Flynn and Michael Shayer, via Rolf Degen.

New Evidence of Generational Progress for Mexican Americans

U.S.-born Mexican Americans suffer a large schooling deficit relative to other Americans, and standard data sources suggest that this deficit does not shrink between the 2nd and later generations. Standard data sources lack information on grandparents’ countries of birth, however, which creates potentially serious issues for tracking the progress of later-generation Mexican Americans. Exploiting unique NLSY97 data that address these measurement issues, we find substantial educational progress between the 2nd and 3rd generations for a recent cohort of Mexican Americans. Such progress is obscured when we instead mimic the limitations inherent in standard data sources.

That is by Brian Duncan, Jeffrey Grogger, Ana Sofia Leon, and Stephen J. Trejo in a recent NBER working paper.

The Power of Abortion Policy

That is by by Caitlin Knowles Myers, and the full title is “The Power of Abortion Policy: Reexamining the Effects of Young Women’s Access to Reproductive Control.”  It is published in the most recent JPE, here is the abstract:

I provide new evidence on the relative “powers” of contraception and abortion policy in effecting the dramatic social transformations of the 1960s and 1970s. Trends in sexual behavior suggest that young women’s increased access to the birth control pill fueled the sexual revolution, but neither these trends nor difference-in-difference estimates support the view that this also led to substantial changes in family formation. Rather, the estimates robustly suggest that it was liberalized access to abortion that allowed large numbers of women to delay marriage and motherhood.

In other words, the pill was less influential than you might think.  And from the paper proper:

…policy environments in which abortion has legal and readily accessible by young women are estimated to have caused a 34 percent reduction in first births, a 19 percent reduction in first marriages, and a 63 percent reduction in “shotgun marriages” prior to age 19.

And:

Between the 1950 and 1955 birth cohorts, the fraction of women having sex prior to age 18 increased from 34 to 47 percent.

And:

…cohorts that experienced the most rapid changes in sexual behavior exhibited little change in fertility.

And:

Lahey (2014)…finds that the introduction of abortion restrictions in the nineteenth century increased birthrates by 4-12 percent…

I thought this was one of the most interesting papers I have read all year.  Here is an earlier, ungated copy.

Vaping Saves Lives

E-cigarettes are less dangerous than cigarettes but are equally effective at delivering nicotine. Levy et al. estimate that if smokers switched to e-cigarettes millions of life-years would be saved, even taking into account plausible rates of non-smokers who start to vape. (It’s worth noting that the authors are all cancer researchers, statisticians and epidemiologists concerned with reducing cancer deaths.)

A Status Quo Scenario, developed to project smoking rates and health outcomes in the absence of vaping, is compared with Substitution models, whereby cigarette use is largely replaced by vaping over a 10-year period. We test an Optimistic and a Pessimistic Scenario, differing in terms of the relative harms of e-cigarettes compared with cigarettes and the impact on overall initiation, cessation and switching. Projected mortality outcomes by age and sex under the Status Quo and E-Cigarette Substitution Scenarios are compared from 2016 to 2100 to determine public health impacts.

Compared with the Status Quo, replacement of cigarette by e-cigarette use over a 10-year period yields 6.6 million fewer premature deaths with 86.7 million fewer life years lost in the Optimistic Scenario. Under the Pessimistic Scenario, 1.6 million premature deaths are averted with 20.8 million fewer life years lost. The largest gains are among younger cohorts, with a 0.5 gain in average life expectancy projected for the age 15 years cohort in 2016.

Vaping saves lives but the FDA has in the past tried to impose severe regulations on the industry and to make vaping less pleasurable. (Aside: It’s interesting that liberals tend to favor other risk-reducing devices such as condoms in the classroom but disfavor vaping while conservatives often take the opposite sides. I don’t think either group is basing their choices on the elasticities.)

The FDA, for example, has tried to ban flavored e-cigarettes. In a new NBER paper, Buckell, Marti and Sindelar calculate that:

…a ban on flavored e-cigarettes would drive smokers to combustible cigarettes, which have been
found to be the more harmful way of getting nicotine (Goniewicz et al., 2017; Shahab et al., 2017).
In addition, such a ban reduces the appeal of e-cigarettes to those who are seeking to quit; ecigarettes
have proven useful as a cessation device for these individuals (Hartmann-Boyce et al.,
2016; Zhu et al., 2017), and we find that quitters have a preference for flavored e-cigarettes.

Fortunately, the new FDA commissioner Scott Gottlieb has signaled a more liberal attitude towards vaping. It could be the most consequential decision of his tenure.

Hat tip: The excellent Robert Wilbin from 80,000 Hours.