Category: Data Source

Texas Covid and school reopenings

Mostly I think American schools have been closed for way too long, but I am typically wary when I read “dogmatic” cases for universal school reopenings, especially when those reopenings are not done under the proper circumstances, namely good data and plenty of testing, or low case levels.  Here is one new piece that sheds some new light on the topic:

This paper examines the effect of fall 2020 school reopenings in Texas on county-level COVID-19 cases and fatalities. Previous evidence suggests that schools can be reopened safely if community spread is low and public health guidelines are followed. However, in Texas, reopenings often occurred alongside high community spread and at near capacity, making it difficult to meet social distancing recommendations. Using event-study models and handcollected instruction modality and start dates for all school districts, we find robust evidence that reopening Texas schools gradually but substantially accelerated the community spread of COVID-19. Results from our preferred specification imply that school reopenings led to at least 43,000 additional COVID-19 cases and 800 additional fatalities within the first two months. We then use SafeGraph mobility data to provide evidence that spillovers to adults’ behaviors contributed to these large effects. Median time spent outside the home on a typical weekday increased substantially in neighborhoods with large numbers of school-age children, suggesting a return to in-person work or increased outside-of-home leisure activities among parents.

That is a new NBER working paper by Charles J. Courtemanche, Anh H. Le, Aaron Yelowitz, and Ron Zimmer.  In other words, having the kids at home kept the adults tied down and less mobile.  Of course, even with this result, there is still a case for reopening the schools, but I am happy to see some of the trade-offs recognized.

Network Structure in Small Groups and Survival in Disasters

I wonder if this kind of result might apply to more than just disasters:

People in disaster and emergency situations (e.g., building fires) tend to adhere to the social obligations and expectations that are embedded in their preexisting roles and relationships. Accordingly, people survive or perish in groups—specifically, alongside those to whom they were connected before the situation emerged. This article uses social network analysis to expand on this collective behavior account. Specifically, we consider structural heterogeneity with respect to the internal configurations of social ties that compose small groups facing these situations together. Some groups are composed of cohesive subsets of members who can split off from each other during evacuation without violating their group’s internal role-based expectations. We argue that groups that possess this “breakaway” structure can respond to emergencies more flexibly. We explore this using data from the Beverly Hills Supper Club fire of 1977, which killed 165 people. Our data include 303 groups (“parties”) that consisted of 746 people who were present in the dining room where most of the fatalities occurred. Fatality rates were significantly lower in groups that were internally structured such that they could split up in different ways during the escape while still maintaining their strongest social bonds.

That is from Benjamin Cornwell and Jing-Mao Ho, via the excellent Kevin Lewis.

Offense vs. defense in the current NBA

…I do have to grudgingly admit the evidence seems to suggest that defense has become less important during this unusual regular season.

One way to look at this is the spread in ratings on both ends of the court. The standard deviation of teams’ defensive ratings relative to league average is the lowest it’s been since the 1984-85 season, while the standard deviation in offensive ratings is the second highest we’ve seen since 2007-08. That’s one way of showing that offense is not just winning the battle with defense but also controlling it.

Another way to show that is the correlation between a team’s defensive rating and its overall win percentage (.546). That’s the lowest it’s been since 1985-86. Meanwhile, there’s a far stronger correlation between a team’s offensive rating and its win percentage (.848). In general, offense tends to relate better to winning games than defense in the NBA. Typically, the two figures are much closer together than we see now.

That is Kevin Pelton, there is further discussion at the ESPN link.  Good news for the Wizards!  It also means you can’t trust your usual intuitions about who might be most likely to win the NBA title this time around.

New results on Work from Home

Emphasis is added by TC:

Using personnel and analytics data from over 10,000 skilled professionals at a large Asian IT services company, we compare productivity before and during the work from home [WFH] period of the Covid-19 pandemic. Total hours worked increased by roughly 30%, including a rise of 18% in working after normal business hours. Average output did not significantly change. Therefore, productivity fell by about 20%. Time spent on coordination activities and meetings increased, but uninterrupted work hours shrank considerably. Employees also spent less time networking, and received less coaching and 1:1 meetings with supervisors. These findings suggest that communication and coordination costs increased substantially during WFH, and constituted an important source of the decline in productivity. Employees with children living at home increased hours worked more than those without children at home, and suffered a bigger decline in productivity than those without children.

That is from a new paper by Michael Gibbs, Friederike Mengel, and Christoph Siemroth.

The New Era of Unconditional Convergence

Here is a new paper by Dev Patel Justin Sandefur, and Arvind Subramanian:

The central fact that has motivated the empirics of economic growthnamely unconditional divergenceis no longer true and has not been so for decades. Across a range of data sources, poorer countries have in fact been catching up with richer ones, albeit slowly, since the mid-1990s. This new era of convergence does not stem primarily from growth moderation in the rich world but rather from accelerating growth in the developing world, which has simultaneously become remarkably less volatile and more persistent. Debates about a middle-income trap also appear anachronistic: middleincome countries have exhibited higher growth rates than all others since the mid-1980s.

Here is the entire paper.  My general conclusion is that no particular model of convergence, or lack thereof, is correct, and it simply all depends on the historical period.

Are women making progress in academic economics?

Here is a new paper by Donna K. Ginther and Shulamit Kahn:

This study uses data from Academic Analytics to examine gender differences in promotion to associate professor in economics. We found that women in economics were 15% less likely to be promoted to associate professor after controlling for cumulative publications, citations, grants and grant dollars. In contrast, we found no significant gender differences in promotion in other fields including biomedical science, physical science, political science, mathematics and statistics, and engineering. We separated the sample by the research intensity of institutions and found suggestive evidence that these results were being driven by less research-intensive institutions.

What is the best model for understanding this result?  The “ol’ boys’ network” matters more at lower-tier institutions?  Something else?  There doesn’t seem to be a gender tenure penalty at higher-ranked research institutions.

The rise of research teams in economics

Solo authorship represented 80 percent of economics papers in 1960 and 65 percent in 1990, but then solo-authorship fell out of the majority in 2005 and represents only 26 percent of economics papers today (as measured by the right-hand axis). To put it another way, in 1950, there were 1.2 authors per economics paper. Average team size reached 2.0 for the first time in 2010. By 2018, team size averaged 2.7 (as shown on the left-hand axis). The jump in average team size in economics papers over the last ten years is greater than the jump over the prior half-century.

Here is more from Benjamin F. Jones.  For higher impact papers, the trend is even more striking.

Concentration in product markets

Here are some new results:

This paper uses new data to reexamine trends in concentration in U.S. markets from 1994 to 2019. The paper’s main contribution is to construct concentration measures that reflect narrowly defined consumption-based product markets, as would be defined in an antitrust setting, while accounting for cross-brand ownership, and to do so over a broad range of consumer goods and services. Our findings differ substantially from well established results using production data. We find that 42.2% of the industries in our sample are “highly concentrated” as defined by the U.S. Horizontal Merger Guidelines, which is much higher than previous results. Also in contrast with the previous literature, we find that product market concentration has been decreasing since 1994. This finding holds at the national level and also when product markets are defined locally in 29 state groups. We find increasing concentration once markets are aggregated to a broader sector level. We argue that these two diverging trends are best explained by a simple theoretical model based on Melitz and Ottaviano (2008), in which the costs of a firm supplying adjacent geographic or product markets falls over time, and efficient firms enter each others’ home product markets.

That is a new NBER working paper by C. Lanier Benkard, Ali Kurukoglu, and Anthony Lee Zhang.  It is very supportive of recent research by Estaben Rossi-Hansberg (here and here, with co-authors) that market concentration simply has not been going up in recent times.

New results on Work From Home

By Jose Maria Barrero, Nicholas Bloom, and Steven J. Davis, there are several points of note, with emphasis added by this author:

COVID-19 drove a mass social experiment in working from home (WFH). We survey more than 30,000 Americans over multiple waves to investigate whether WFH will stick, and why. Our data say that 20 percent of full workdays will be supplied from home after the pandemic ends, compared with just 5 percent before. We develop evidence on five reasons for this large shift: better-than-expected WFH experiences, new investments in physical and human capital that enable WFH, greatly diminished stigma associated with WFH, lingering concerns about crowds and contagion risks, and a pandemic-driven surge in technological innovations that support WFH. We also use our survey data to project three consequences: First, employees will enjoy large benefits from greater remote work, especially those with higher earnings. Second, the shift to WFH will directly reduce spending in major city centers by at least 5-10 percent relative to the pre-pandemic situation. Third, our data on employer plans and the relative productivity of WFH imply a 5 percent productivity boost in the post-pandemic economy due to re-optimized working arrangements. Only one-fifth of this productivity gain will show up in conventional productivity measures, because they do not capture the time savings from less commuting.

Here is the link to the NBER working paper.

Positive externalities through family member incarceration?

This result surprised me, but perhaps there are gains from getting the bad apples out of the household?:

Every year, millions of Americans experience the incarceration of a family member. Using 30 years of administrative data from Ohio and exploiting differing incarceration propensities of randomly assigned judges, this paper provides the first quasi-experimental estimates of the effects of parental and sibling incarceration in the US. Parental incarceration has beneficial effects on some important outcomes for children, reducing their likelihood of incarceration by 4.9 percentage points and improving their adult neighborhood quality. While estimates on academic performance and teen parenthood are imprecise, we reject large positive or negative effects. Sibling incarceration leads to similar reductions in criminal activity.

That is new from Samuel Norris, Matthew Pecenco, and Jeffrey Weaver, forthcoming in the AER.  Via Ilya Novak.  Here is Noah on this study, here is a related result from Sweden.

What predicts professional philosophers’ views?

The entire piece is interesting, but this segment caught my eye in particular:

Additionally, they found that being more politically right-leaning was associated with several philosophical views, such as theism, free will libertarianism, nonphysicalist views in philosophy of mind, and the correspondence theory of truth.

Here is more from Justin Weinberg.  Belief in hard determinism, by the way, is correlated with lower levels of happiness.

I say this all boosts Strauss in relative status.  It is important to believe that people really are special and possess agency, no matter what the actual truth.

The American economy circa 2021

Spending on cars and trucks is 15.1 percent higher than it would have been on the 2019 trajectory; spending on furnishings and durable household equipment is 16.6 percent higher; and spending on recreational goods is a whopping 26 percent higher.

Altogether, durable goods spending is running $348.5 billion higher annually than it would have been in that alternate universe, as Americans have spent their stimulus checks and unused travel money on physical items.

The housing sector is experiencing nearly as big a surge. Residential investment was 14.4 percent above its prepandemic trend, representing $90 billion a year in extra activity. And that was surely constrained by shortages of homes to sell, and lumber and other materials used to make them. It is poised to soar further in coming months, based on forward-looking data like housing starts.

Another bright spot is business investment in information technology. The tech industry has been comparatively unscathed by the crisis. Spending on information processing equipment in the first quarter was 23 percent higher than its prepandemic trend, and investment in software 7.4 percent higher.


Spending on transportation services remains 23 percent below its prepandemic trend, recreation services 31 percent, and restaurants and hotels 19 percent.

Those three sectors alone represent $430 billion in “missing” economic activity — largely equivalent, it’s worth noting, to the combined shift of economic activity toward durable goods and residential real estate.

A corollary shows up in trade data. Services exports are down 26 percent compared with the prepandemic trend, which reflects in significant part the freeze-up in global travel.

Here is the full NYT story.

Facts about biomass

The carbonaceous winners are plants, which make up about 80 percent of all biomass on Earth. Bacteria comes in second at 13 percent and fungus is third at just 2 percent.

Of the 550 gigatons of biomass carbon on Earth, animals make up about 2 gigatons, with insects comprising half of that and fish taking up another 0.7 gigatons. Everything else, including mammals, birds, nematodes and mollusks are roughly 0.3 gigatons, with humans weighing in at 0.06 gigatons. The research appears in The Proceedings of the National Academy of Sciences.

“The fact that the biomass of fungi exceeds that of all animals’ sort of puts us in our place,” Harvard evolutionary biologist James Hanken, who was not involved with the study, tells Borenstein.

Here is the full piece.  And from the cited research article:

…the biomass of domesticated poultry (≈0.005 Gt C, dominated by chickens) is about threefold higher than that of wild birds…

…the total plant biomass (and, by proxy, the total biomass on Earth) has declined approximately twofold relative to its value before the start of human civilization. The total biomass of crops cultivated by humans is estimated at ≈10 Gt C, which accounts for only ≈2% of the extant total plant biomass…

In terms of biomass, mollusks are a bigger deal than you might think.

Are Covid travel bans counterproductive for emerging economies?

Sometimes, yes:

…two opposing forces constitute the first-order determinants of total infections at any point in time.  On one hand, the longer a travel ban lasts, the less time community transmission exists in the rural sink.  Ceteris paribus, this will decrease rural infections.  On the other hand, the longer the restrictions remain, the longer migrants are contained within a hotspot where infection rates are rapidly increasing.  Consequently, the probability that migrants are infected with Covid-19  rises over time until the city achieves herd immunity, in turn increasing the rate at which they seed the rural sink with infections once the ban is lifted.  This drives up cumulative cases at any future date.

In some cases, for travel bans to work they have to be very long.  That is from a new paper by Fiona Burlig, Anant Sudarshan, Garrison Schlauch, who also provide evidence from India, and also from cross-country evidence, to support their analysis.