Category: Economics

Air Pollution Reduces IQ, a Lot

The number and quality of studies showing that air pollution has very substantial effects on health continues to increase. Patrick Collison reviews some of the most recent studies on air pollution and cognition. I’m going to post the whole thing so everything that follows is Patrick’s.

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Air pollution is a very big deal. Its adverse effects on numerous health outcomes and general mortality are widely documented. However, our understanding of its cognitive costs is more recent and those costs are almost certainly still significantly under-emphasized. For example, cognitive effects are not mentioned in most EPA materials.

World Bank data indicate that 3.7 billion people, about half the world’s population, are exposed to more than 50 µg/m³ of PM2.5 on an annual basis, 5x the unit of measure for most of the findings below.

  • Substantial declines in short-term cognitive performance after short-term exposure to moderate (median 27.0 µg/m³) PM2.5 pollution: “The results from the MMSE test showed a statistically robust decline in cognitive function after exposure to both the candle burning and outdoor commuting compared to ambient indoor conditions. The similarity in the results between the two experiments suggests that PM exposure is the cause of the short-term cognitive decline observed in both.” […] “The mean average [test scores] for pre and post exposure to the candle burning were 48 ± 16 and 40 ± 17, respectively.” – Shehab & Pope 2019.
  • Chess players make more mistakes on polluted days: “We find that an increase of 10 µg/m³ raises the probability of making an error by 1.5 percentage points, and increases the magnitude of the errors by 9.4%. The impact of pollution is exacerbated by time pressure. When players approach the time control of games, an increase of 10 µg/m³, corresponding to about one standard deviation, increases the probability of making a meaningful error by 3.2 percentage points, and errors being 17.3% larger.” – Künn et al 2019.
  • A 3.26x (albeit with very wide CI) increase in Alzheimer’s incidence for each 10 µg/m³ increase in long-term PM2.5 exposure? “Short- and long-term PM2.5 exposure was associated with increased risks of stroke (short-term odds ratio 1.01 [per µg/m³ increase in PM2.5 concentrations], 95% CI 1.01-1.02; long-term 1.14, 95% CI 1.08-1.21) and mortality (short-term 1.02, 95% CI 1.01-1.04; long-term 1.15, 95% CI 1.07-1.24) of stroke. Long-term PM2.5 exposure was associated with increased risks of dementia (1.16, 95% CI 1.07-1.26), Alzheimer’s disease (3.26, 95% 0.84-12.74), ASD (1.68, 95% CI 1.20-2.34), and Parkinson’s disease (1.34, 95% CI 1.04-1.73).” – Fu et al 2019. Similar effects are seen in Bishop et al 2018: “We find that a 1 µg/m³ increase in decadal PM2.5 increases the probability of a dementia diagnosis by 1.68 percentage points.”
  • A study of 20,000 elderly women concluded that “the effect of a 10 µg/m³ increment in long-term [PM2.5 and PM10] exposure is cognitively equivalent to aging by approximately 2 years”. – Weuve et al 2013.
  • “Utilizing variations in transitory and cumulative air pollution exposures for the same individuals over time in China, we provide evidence that polluted air may impede cognitive ability as people become older, especially for less educated men. Cutting annual mean concentration of particulate matter smaller than 10 µm (PM10) in China to the Environmental Protection Agency’s standard (50 µg/m³) would move people from the median to the 63rd percentile (verbal test scores) and the 58th percentile (math test scores), respectively.” – Zhang et al 2018.
  • “Exposure to CO2 and VOCs at levels found in conventional office buildings was associated with lower cognitive scores than those associated with levels of these compounds found in a Green building.” – Allen et al 2016. The effect seems to kick in at around 1,000 ppm of CO2.

Alex again. Here’s one more. Heissel et al. (2019):

“We compare within-student achievement for students transitioning between schools near highways, where one school has had greater levels of pollution because it is downwind of a highway. Students who move from an elementary/middle school that feeds into a “downwind” middle/high school in the same zip code experience decreases in test scores, more behavioral incidents, and more absences, relative to when they transition to an upwind school”

Relatively poor countries with extensive air pollution–such as India–are not simply choosing to trade higher GDP for worse health; air pollution is so bad that countries with even moderate air pollution are getting lower GDP and worse heath.

Addendum: Patrick has added a few more.

Is the rate of scientific progress slowing down?

That is the title of my new paper with Ben Southwood, here is one segment from the introduction:

Our task is simple: we will consider whether the rate of scientific progress has slowed down, and more generally what we know about the rate of scientific progress, based on these literatures and other metrics we have been investigating. This investigation will take the form of a conceptual survey of the available data. We will consider which measures are out there, what they show, and how we should best interpret them, to attempt to create the most comprehensive and wide-ranging survey of metrics for the progress of science.  In particular, we integrate a number of strands in the productivity growth literature, the “science of science” literature, and various historical literatures on the nature of human progress. In our view, however, a mere reporting of different metrics does not suffice to answer the cluster of questions surrounding scientific progress. It is also necessary to ask some difficult questions about what science means, what progress means, and how the literatures on economic productivity and “science on its own terms” might connect with each other.

Mostly we think scientific progress is indeed slowing down, and this is supported by a wide variety of metrics, surveyed in the paper.  The gleam of optimism comes from this:

And to the extent that progress in science has not been slowing down, which is indeed the case under some of our metrics, that may give us new insight into where the strengths of modern and contemporary science truly lie. For instance, our analysis stresses the distinction between per capita progress and progress in the aggregate. As we will see later, a wide variety of “per capita” measures do indeed suggest that various metrics for growth, progress and productivity are slowing down. On the other side of that coin, a no less strong variety of metrics show that measures of total, aggregate progress are usually doing quite well. So the final answer to the progress question likely depends on how we weight per capita rates of progress vs. measures of total progress in the aggregate.

What do the data on productivity not tell us about scientific progress?  By how much is the contribution of the internet undervalued?  What can we learn from data on crop yields, life expectancy, and Moore’s Law?  Might the social sciences count as an example of progress in the sciences not slowing down?  Is the Solow model distinction between “once and for all changes” and “ongoing increases in the rate of innovation” sound?  And much more.

Your comments on this paper would be very much welcome, either on MR or through email.  I will be blogging some particular ideas from the paper over the next week or two.

And here is Ben on Twitter.

The future of higher education?

Two public four-year institutions, Maine Maritime Academy and the U.S. Merchant Marine Academy, rank in the top 10 colleges with the best long-term returns, while two four-year private colleges, St. Louis College of Pharmacy and Albany College of Pharmacy and Health Sciences, made the top 10 for short-term and long-term returns.

The report ranks 4,526 colleges and universities by return on investment.

Here is one article, with a graphic for the top ten, you will note that Harvard, Stanford, and MIT still do fine.  Babson is underrated, as it does much better over longer stretches of time.  Here is the Georgetown report.

Wojciech Kopczuk on wealth taxation

His comment on Saez and Zucman is one of the best pieces of policy economics I have read in the last few years.  Many of the main arguments have been debated on Twitter, or expressed by Larry Summers, so here I will stick with a few side points that have not received full attention.

First, if you hate monopoly rents, excess IP income, and the like, you should not be in love with a wealth tax, at least not in the steady state!  A wealth tax hits the base and the safe rate of return as well.  Ideally the anti-monopoly crowd should most of all favor higher taxes on net income.  Not taxes on wealth.

Second, a wealth tax will encourage the shifting of much more production into non-profit institutions, or perhaps even into nationalizations of industry.  Lots of hospitals would switch back to the not-for-profit form, not obviously a beneficial development in my view.

As a side note, many more non-profits would hire famous musical acts to play at their donor galas.  The quality of champagne and cheese at those events will rise too.  There would be much more pressure on non-profits to create private (non-taxed) benefits for their donors.  I predict government regulation of non-profits would end up rising considerably as well, and not for the better.

Privatizing government assets such as land or spectrum would become more difficult — people would buy only at much lower prices.  So the wealth tax is a recipe for greater statism in more ways than one.

Third, under a wealth tax Jeff Bezos would have lost de facto control over Amazon some time ago.

Those are my words rather than Kopfczuk’s, do read his entire paper.

I would add one final point.  I think we are at the margin where advocacy of a wealth tax is more of a performative exercise — “we hadn’t poked rich people in the eye with this rhetorical needle yet, therefore I won’t really speak against it” — than any kind of substantive analytic debate.

Garett Jones on open borders

I am very pleased that the new Bryan Caplan and Zach Weinersmith open borders graphic novel has hit #1 on The Washington Post non-fiction bestseller list.  I am also pleased to see Garett Jones examine the idea in a new short paper, here is part of his critique:

I use the same constant returns to scale framework as Caplan, in which the migration of every human being to the United States would increase global output per capita by about 80%. I then estimate that in the benchmark model, where IQ’s social return is much larger than its private return, the per-capita income of current U.S.residents would permanently fall by about 40%. This is not an arithmetic fallacy: this is the average causal effect of Open Borders on the incomes of ex-ante Americans. This income decline occurs because cognitive skills matter mostly through externalities: because your nation’s IQ matters so much more than your own, as I claim in 2015’s Hive Mind. Therefore, a decline in a nation’s set of average cognitive skills will tend to reduce the productivity of the nation’s ex-ante citizens.

I will be sure to link to Bryan’s reply when it comes.

Social Security isn’t doomed for younger generations

No, it is not one of the great Boomer rip-offs, as I argue in my latest Bloomberg column.  Here is one excerpt:

According to his [Blahous’s] estimates [link here], if no further steps are taken to shore up the finances of Social Security, the system will stop being able to meet its scheduled payment obligations sometime in the 2030s. (Note that benefit hikes are part of the schedule.) That would be bad, but even under this scenario the system is still paying out a roughly constant level of inflation-adjusted benefits over time, at least as those benefits are defined as a percentage of workers’ taxable earnings (about 13%). Of course, to the extent those taxable earnings rise, the benefits will be rising too, even if not at a spectacular pace.

Keep in mind that this is the worst-case scenario offered by a relative pessimist.

Another way to describe the problem is that, over the next 75 years, about 17% of scheduled benefits are currently unfinanced. Blahous estimates that the U.S. could cover that gap if the Social Security payroll tax were raised from 12.4% to 15.1%.

Now, you might have strong views about the wisdom of that kind of tax increase, but you should acknowledge that this is a very different reality than a bankrupt system. With Social Security on full cruise control, and with no forward-looking reforms, today’s younger earners still are slated to receive more than their parents did — just not very much more.

Dean Baker, an economist to the left of Blahous, also has studied Social Security. He estimates that retirees 30 to 40 years from now will receive monthly checks that are about 10% higher in real terms than today’s benefits. And keep in mind those are estimates per year. To the extent life expectancy rises, total benefits received will be higher yet.

The winners and losers from Airbnb

Overall, renters in New York City suffer a loss of $178mm per annum, as the losses from the rent channel dominate the gains from the host channel. I find that the increased rent burden falls most heavily on high-income, educated, and white renters, because they prefer housing and location amenities most desirable to tourists. Moreover, there is a divergence between the median and the tail, where a few enterprising low-income households obtain substantial gains from home-sharing, especially during demand peaks.

That is from the job market paper of Sophie Calder-Wang of Harvard.  You will note there still are likely net gains once you count tourist demand, but of course this helps explain why Airbnb rentals are unpopular in some cities.

Politically Incorrect Paper of the Day: The United Fruit Company was Good!

The United Fruit Company is the bogeyman of Latin America, the very apotheosis of neo-colonialism. And to be sure in the UFC history there is wrongdoing and plenty of fodder for conspiracy theories but the UFC also brought bananas (as export crop), tourism, and in many cases good governance to parts of Latin America. Much, however, depends on the institutional constraints within which the company operated. Esteban Mendez-Chacon and Diana Van Patten (on the job market) look at the UFC in Costa Rica.

The UFC needed to bring workers to remote locations and thus it invested heavily in worker welfare:

the UFC invested in sanitation infrastructure, launched health programs, and provided medical attention to its employees. Infrastructure investments included pipes, drinking water systems, sewage system, street lighting, macadamized roads, a dike (Sanou and Quesada, 1998), and by 1942 the company operated three hospitals in the country.

Given the remoteness the plantations and to reduce transportation costs, the UFC provided the majority of its workers with free housing within the company’s land. This was partially motivated by concerns with diseases like malaria and yellow fever, which spread easily if the population is constantly commuting from outside the plantation. By 1958 the majority of laborers lived in barracks-type structures… [which] exceeded the standards of many surrounding communities (Wiley, 2008).

Image result for united fruit companyThe UFC wasn’t just interested in healthy workers, they also needed to attract workers with stable families:

One of the services that the company provided within its camps was primary education to the children of its employees. The curriculum in the schools included vocational training and before the 1940s, was taught mostly in English. The emphasis on primary education was significant, and child labor became uncommon in the banana regions (Viales, 1998). By 1955, the company had constructed 62 primary schools within its landholdings in Costa Rica (May and Lasso, 1958). As shown in Figure 6a,spending per student in schools operated by the UFC was consistently higher than public spending in primary education between 1947 and 1963.21 On average, the company’s yearly spending was 23% higher than the government’s spending during this period.

…The UFC did not provide directly secondary education although offered some incentives. If the parents could afford the first two years of secondary education of their children in the United States, the UFC paid for the last two years and provided free transportation to and from the United States.

A key driver of UFC investment was that although the UFC was the sole employer within the regions in which it operated, it had to compete to obtain labor from other regions. Thus a 1925 UFC report writes:

We recommend a greater investment in corporate welfare beyond medical measures. An endeavor should be made to stabilize the population…we must not only build and maintain attractive and comfortable camps, but we must also provide measures for taking care of families of married men, by furnishing them with garden facilities, schools, and some forms of entertainment. In other words, we must take an interest in our people if we might hope to retain their services indefinitely.

This is exactly the dynamic which drove the provision of services and infrastructure in unjustly maligned US company towns. It’s also exactly what Rajagopalan and I found in the Indian company town of Jamshedpur, built by Jamshetji Nusserwanji Tata.

The UFC ended in Costa Rica in 1984 but the authors find that it had a long-term positive impact. Using historical records, the authors discover a plausibly randomly-determined boundary line between UFC and non-UFC areas and comparing living standards just inside and just outside the boundary they find that households within the boundary today have better housing, sanitary conditions, education and consumption than households just outside the boundary. Overall:

We find that the firm had a positive and persistent effect on living standards. Regions within the UFC were 26% less likely to be poor in 1973 than nearby counterfactual locations, with only 63% of the gap closing over the following 3 decades.

The paper has appendixes A-J. In one appendix (!), they show using satellite data that regions within the boundary are more luminous at night than those just outside the region. The collection of data is especially notable:

For a better understanding of living standards and investments during UFC’s tenure, we collected and digitized UFC reports with data on wages, number of employees, production, and investments in areas such as education, housing, and health from collections held by Cornell University, University of Kansas, and the Center for Central American Historical Studies. We also use annual reports from the Medical Department of the UFC describing the sanitation and health programs and spending per patient in company-run hospitals from 1912 to 1931. We also collected data from Costa Rican Statistic Yearbooks, which from 1907 to 1917 contain details on the number of patients and health expenses carried out by hospitals in Costa Rica, including the ones ran by the UFC. Export data was also collected from these yearbooks, and from Export Bulletins. 19 agricultural censuses taken between 1900 and 1984 provide information on land use, and we use data from Costa Rican censuses between 1864-1963 to analyze aggregated population patterns, such as migration before and during the UFC apogee, or the size and occupation of the country’s labor force.

Overall, a tremendous paper.

A Coasean solution for New Delhi?

If the late Ronald Coase could be called upon to advise the Delhi government, he would persuade chief minister Arvind Kejriwal to pay farmers in Punjab and Haryana to stop burning crop residue.

In recent times, air quality in Delhi has remained poor throughout the year for various reasons, including the rapid loss of green cover, construction of homes and infrastructure projects, and vehicular as well as industrial pollution. But for a few weeks every November, it gets almost impossible to breathe. The last straw has been the crop residue burning (CRB) by farmers in Punjab and Haryana, which causes a heavy smog to settle over Delhi…

The good news is that these [health] costs—avoidable by Delhi residents if CRB were eliminated—are about 10 times the cost that would be incurred by farmers in adopting substitutes to crop burning. Where policymakers see costs, Coase saw potential for gains from trade.

Here is more from Shruti Rajagopalan.

Do the rich save more?

Yes, not a surprise but here are some details:

We identify a strong negative relationship between the consumption rate and the lifetime net resource. The predicted APC [average propensity to consume] of the highest net resource cohort about 0.03, which is two standard deviations smaller than the lowest resource cohort.

That is from a new paper by Ilin, Ye, and Yu (Yu is on the job market).  Of course this relates to the recent wealth tax debate — almost all of that tax would fall on the investment of the wealthy, not their consumption.  Note, however, that if the wealth tax induced more consumption by the wealthy, consumption inequality could quite easily go up.

Rent control is also not great for labor market outcomes

I had never thought of this before:

This paper, using a novel data set on rent stabilization in New  York City, takes a first step in investigating the policy’s unintended consequences on tenant labor market outcomes, while also exploring the impact of policy awareness on those outcomes. Recognizing the potential endogeneity of living in a rent-stabilized unit, this paper uses three decades of housing vacancy data to construct an instrumental variable leveraging variation in the availability of rent-stabilized units across New York boroughs over time. The sorted effects method in Chernozhukov, Fern´andez-Val, and Luo (2018) is also applied to investigate heterogeneous effects beyond their averages. The main results demonstrate that rent-stabilized tenants are more likely to be unemployed compared with tenants in private market-rate units. These effects are particularly salient among white and high-skilled tenants.

That is from the job market paper of Hanchen Jiang of Johns Hopkins University.

Consistency about elasticities, revisited

From Ross Rheingans-Yoo, the content is all his, I will not do a double indent:

  • If marginal wealth is taxed an additional 0.5%/yr at the high end, then fewer people will amass and invest that much wealth—some will instead disperse it among a wider number of family members, donate it to charitable or political causes, or spend it on expensive consumption. (Saez and Zucman, in their potential-revenue analyses, assume that this effect is quite small, and that the wealthy will mostly accept lower returns on wealth.)
  • Similarly, if the marginal opportunities to invest became worse by 0.5%/yr, fewer people would chose to invest, by the same token. Additionally,the effects should be the same size, as it’s the same decision-makers facing the same incentives!
  • But if pushing on the price (read: rate of return) has little effect on the quantity of investment, then pushing on the quantity of investment should have a large​ effect on the price! (Unless we’re at some magic kink in the supply curve for unspecified reasons…)
  • So a small amount of additional capital competing for investment opportunities should quickly reduce the competitive rate of return.

What’s the practical upshot? Well, if the authors’ assumptions about revenues are right, then Piketty’s r>gr>g “wealth spiral” can’t proceed unchecked, since capital simply can’t accumulate without competition quickly reducing the average rate of return back below gg.

Effort: The Unrecognized Contributor to US Income Inequality

That is a new paper by J. Rodrigo Fuentes and Edward E. Leamer:

This paper provides theory and evidence that worker effort has played an important role in the increase in income inequality in the United States between 1980 and 2016. The theory suggests that a worker needs to exert effort enough to pay the rental value of the physical and human capital, thus high effort and high pay for jobs operating expensive capital. With that as a foundation, we use data from the ACS surveys in 1980 and 2016 to estimate Mincer equations for six different education levels that explain wage incomes as a function of weekly hours worked and other worker features. One finding is a decline in annual income for high school graduates for all hours worked per week. We argue that the sharp decline in manufacturing jobs forces down wages of those with high school degrees who have precious few high-effort opportunities outside of manufacturing. Another finding is that incomes rose only for those with advanced degrees and with weekly hours in excess of 40. We attribute this to the natural talent needed to make a computer deliver exceptional value and to the relative ease with which long hours can be chosen when working over the Internet.

I like that last sentence in particular.