What Worked in 1918-1919?

The influenza pandemic of 1918 was the most contagious calamity in human history. Approximately 40 million individuals died worldwide, including 550 000 individuals in the United States...[C]an lessons from the 1918-1919 pandemic be applied to contemporary pandemic planning efforts to maximize public health benefit while minimizing the disruptive social consequences of the pandemic as well as those accompanying public health response measures?

That’s the question Markel et al. analyzed in 2007 by gathering historical data on outcomes and what 43 US cities, covering about 20% of the US population, did to combat influenza in 1918-1919.

Nonpharmaceutical interventions were considered either activated (“on”) or deactivated (“off”), according to data culled from the historical record and daily newspaper accounts. Specifically, these nonpharmaceutical interventions were legally enforced and affected large segments of the city’s population. [1] Isolation of ill persons and quarantine of those suspected of having contact with ill persons refers only to mandatory orders as opposed to voluntary quarantines being discussed in our present era. [2] School closure was considered activated when the city officials closed public schools (grade school through high school); in most, but not all cases, private and parochial schools followed suit. [3] Public gathering bans typically meant the closure of saloons, public entertainment venues, sporting events, and indoor gatherings were banned or moved outdoors; outdoor gatherings were not always canceled during this period (eg, Liberty bond parades); there were no recorded bans on shopping in grocery and drug stores.

The authors define “public health response time” as the number of days from the day the excess death rate was double baseline to the day that at least one of their three key public health measures was implemented. Cities that responded very early have a negative public health response time. The basic result is shown in the figure below. The longer the public health response time the greater the total excess deaths (the arrow is my least squares eyeball).

Moreover, although it’s difficult to control for other factors, cities that combined school closures, isolation and quarantining, and public gathering bans tended to do better. Some cities let up on their public health interventions and these cities seem to correlate well with bi-modal distributions in excess death rates, i.e. the death rate increased. Denver was an example where the public gathering ban was dropped and the school ban was lifted temporarily and the excess death rate rose after having fallen.

The authors conclude:

…the US urban experience with nonpharmaceutical interventions during the 1918-1919 pandemic constitutes one of the largest data sets of its kind ever assembled in the modern, post germ theory era.

…Although these urban communities had neither effective vaccines nor antivirals, cities that were able to organize and execute a suite of classic public health interventions before the pandemic swept fully through the city appeared to have an associated mitigated epidemic experience. Our study suggests that nonpharmaceutical interventions can play a critical role in mitigating the consequences of future severe influenza pandemics (category 4 and 5) and should be considered for inclusion in contemporary planning efforts as companion measures to developing effective vaccines and medications for prophylaxis and treatment. The history of US epidemics also cautions that the public’s acceptance of these health measures is enhanced when guided by ethical and humane principles.

Addendum: Another way of putting this is that China has largely followed the US model. Can the US do the same?

Women in Economics: Janet Yellen

Here’s a great new video on Janet Yellen from our team at MRU. In addition to Yellen, the video features Ben Bernanke and Christina Romer, who is tremendous. Other videos in the series are on Anna Schwartz and Elinor Ostrom with more on the way. The video is excellent but my favorite MRU video with Yellen has her in superhero mode.

Instructors, feel free to use these videos in any of your classes. Of course, you can also find these videos integrated with our textbook.

By the way, here is Adams and Yellen’s classic paper on bundling (ungated) and you can find an introduction to bundling in this video.

The Consequences of Treating Electricity as a Right

In poor countries the price of electricity is low, so low that “utilities lose money on every unit of electricity that they sell.” As a result, rationing and shortages are common. Writing in the JEP, Burgess, Greenstone, Ryan and Sudarshan argue that “these shortfalls arise as a consequence of treating electricity as a right, rather than as a private good.”

How can treating electricity as a right undermine the aim of universal access to reliable electricity? We argue that there are four steps. In step 1, because electricity is seen as a right, subsidies, theft, and nonpayment are widely tolerated. Bills that do not cover costs, unpaid bills, and illegal grid connections become an accepted part of the system. In step 2, electricity utilities—also known as distribution companies—lose money with each unit of electricity sold and in total lose large sums of money. Though governments provide support, at some point, budget constraints start to bind. In step 3, distribution companies have no option but to ration supply by limiting access and restricting hours of supply. In effect, distribution companies try to sell less of their product. In step 4, power supply is no longer governed by market forces. The link between payment and supply has been severed: those evading payment receive the same quality of supply as those who pay in full. The delinking of payment and supply reinforces the view described in step 1 that electricity is a right [and leads to] a low-quality, low-payment equilibrium.

The Burgess et al. analysis coheres with my observations in India where “wire anarchy” is common (see picture). It’s obvious that electricity is being stolen but no one does anything about it because it’s considered a right and a government that did do something about it would be voted out of power.

The stolen electricity means that the utility can’t cover its costs. Government subsidies are rarely enough to satisfy the demand at a zero or low price and so the utility rations.

The consequences for electricity consumers, both rich and poor, are severe. There is only one electricity grid, and it becomes impossible to offer a higher quantity or quality of supply to those consumers who are willing and sometimes even desperate to pay for it.

Moreover,the issue is not poverty per se.

…the vast majority of customers in Bihar expect no penalty from paying a bill late, illegally hooking into the grid, wiring around a meter, or even bribing electricity officials to avoid payment. These attitudes are in stark contrast to how the same consumers view payment for private goods like cellphones. It is debatable whether cellphones are more important than electricity, but in Bihar we find that the poor spend three times more on cellphones than they do on elec-tricity (1.7 versus 0.6 percent of total expenditure).

Burgess et al. frame the issue as “treating electricity as right,” but one can can also understand this equilibrium as arising from low state capacity and corruption, in particular corruption with theft. In corruption with theft the buyer pays say a meter reader to look the other way as they tap into the line and they get a lower price for electricity net of the bribe. Corruption with theft is a strong equilibrium because buyers who do not steal have higher costs and thus are driven out of the market. In addition, corruption with theft unites the buyer and the corrupt meter reader in secrecy, since both are gaining from the transaction. As Shleifer and Vishny note:

This result suggests that the first step to reduce corruption should be to create an accounting system that prevents theft from the government.

Burgess et al. agree noting, “reforms might seek to reduce theft of electricity and nonpayment of bills” and they point to programs in India and Pakistan that allow utilities to cut off entire neighborhoods when bills aren’t paid. Needless to say, such hardball tactics require some level of trust that when the bills are paid the electricity will be provided and at higher levels of quality–this may be easier to do when there are other sources of authority such as trusted religious leaders.

In essence the problem is that the government is too beholden to electricity consumers. If the government could commit to a regime of no or few subsidies, firms would supply electricity and prices would be low and quality high. But if firms do invest in the necessary electricity infrastructure the government will break its promise and exploit the firms for temporary electoral advantage. As a result, the consumers don’t get much electricity. The government faces a time consistency problem. Independent courts would help to bind the government but those often aren’t available in developing countries. Another possibility is a conservative electricity czar who, like a conservativer central banker, doesn’t share the preferences of the government or the voters. Again that requires some independence.

In short, to ensure that everyone has access to high quality electricity the government must credibly commit that electricity is not a right.

Spock’s Brain

The Santa Monica Observer noted the death of soap opera actress Marj Dusay who also appeared as the alien thief in the classic Start Trek episode “Spock’s Brain”:

…The episode is generally regarded by most fans, and those who took part in its production, as the worst episode of the series. William Shatner called this one of the series’ worst episodes, calling the episode’s plot a “tribute” to NBC executives who slashed the show’s budget and placed it in a bad time slot.

Leonard Nimoy wrote: “Frankly, during the entire shooting of that episode, I was embarrassed – a feeling that overcame me many times during the final season of Star Trek.”

…In his book What Were They Thinking? The 100 Dumbest Events in Television History, author David Hofstede ranked the episode at #71 on the list.

The rock band Phish performs a song entitled “Spock’s Brain”

So what? Well here is the part that caught my attention:

The episode was referenced in Modern Principles: Microeconomics by Tyler Cowen and Alex Tabarrok of George Mason University as an example of how it is virtually impossible to have a command economy; in that not even Spock’s brain could run an economy.

In other words, we also thought it was one of the worst episodes ever because of the bad economics. Econ instructors should use our textbook! Where else can you learn about Spock’s Brain and the command economy?

By the way, I’m pretty sure the obit was AI generated but heh the AI did a good job! I am aware of the irony.

The WHO Report on COVID-19

The Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) is the best source of information on COVID-19 that I have seen.

The Joint Mission consisted of 25 national and international experts from China, Germany, Japan, Korea, Nigeria, Russia, Singapore, the United States of America and the World Health Organization (WHO). The Joint Mission was headed by Dr Bruce Aylward of WHO and Dr Wannian Liang of the People’s Republic of China.

Some of the language is more pro-China than is usual in an academic report but the report is full of credible data.

The bottom line is that there is good news and bad news. The good news is that due to extraordinary intervention the epidemic in China has been brought under control and is slowing to manageable levels.

In the face of a previously unknown virus, China has rolled out perhaps the most ambitious, agile and aggressive disease containment effort in history. The strategy that underpinned this containment effort was initially a national approach that promoted universal temperature monitoring, masking, and hand washing. However, as the outbreak evolved, and knowledge was gained, a science and risk-based approach was taken to tailor implementation. Specific containment measures were adjusted to the provincial, county and even community context, the capacity of the setting, and the nature of novel coronavirus transmission there.

…. China’s bold approach to contain the rapid spread of this new respiratory pathogen has changed the course of a rapidly escalating and deadly epidemic. A particularly compelling statistic is that on the first day of the advance team’s work there were 2478 newly confirmed cases of COVID-19 reported in China. Two weeks later, on the final day of this Mission, China reported 409 newly confirmed cases. This decline in COVID-19 cases across China is real.

Based on a comparison of crude attack rates across provinces, the Joint Mission estimates that this truly all-of Government and all-of-society approach that has been taken in China has averted or at least delayed hundreds of thousands of COVID-19 cases in the country. By extension, the reduction that has been achieved in the force of COVID-19 infection in China has also played a significant role in protecting the global community and creating a stronger first line of defense against international spread. Containing this outbreak, however, has come at great cost and sacrifice by China and its people, in both human and material terms.

The bad news is that the WHO is worried that other countries do not have the capability or will to implement some of the same policies as China did.

Much of the global community is not yet ready, in mindset and materially, to implement the measures that have been employed to contain COVID-19 in China. These are the only measures that are currently proven to interrupt or minimize transmission chains in humans. Fundamental to these measures is extremely proactive surveillance to immediately detect cases, very rapid diagnosis and immediate case isolation, rigorous tracking and quarantine of close contacts, and an exceptionally high degree of population understanding and acceptance of these measures.

.. COVID-19 is spreading with astonishing speed; COVID-19 outbreaks in any setting have very serious consequences; and there is now strong evidence that non-pharmaceutical interventions can reduce and even interrupt transmission. Concerningly, global and national preparedness planning is often ambivalent about such interventions. However, to reduce COVID-19 illness and death, near-term readiness planning must embrace the large-scale implementation of high-quality, non-pharmaceutical public health measures. These measures must fully incorporate immediate case detection and isolation, rigorous close contact tracing and monitoring/quarantine, and direct population/community engagement.

I don’t think the WHO is the final authority on what to do, public health is their hammer. I have been dismayed, however, at the failure of the CDC, which surely prior to this crisis one would have rated as one of the best US organizations. As the NYTimes wrote:

The Centers for Disease Control and Prevention botched its first attempt to mass produce a diagnostic test kit, a discovery made only after officials had shipped hundreds of kits to state laboratories.

A promised replacement took several weeks, and still did not permit state and local laboratories to make final diagnoses. And the C.D.C. essentially ensured that Americans would be tested in very few numbers by imposing stringent and narrow criteria, critics say.

The failure of the CDC, which is a failure of the US government at the deepest levels, not just rot from the top, meant that we lost several weeks that we may have needed to avoid more stringent measures. We will know more in a week.

Read the whole thing.

Free Tool to Run the Double Oral Auction Experiment

The double oral auction was one of the first experiments that Vernon Smith ran. He was expecting to find that the supply and demand model didn’t work. Instead, the results changed his life and led to a Nobel prize:

I am still recovering from the shock of the experimental results. The outcome was unbelievably consistent with competitive price theory. … But the result can’t be believed, I thought. It must be an accident, so I will take another class and do a new experiment with different supply and demand schedules. (Smith 1991)

I’ve run similar experiments in my principles class. The exercise is fun for the students and it’s always amazing to see how quickly the equilibrium is attained even though none of the participants has any idea what the equilibrium price and quantity are. The experiment can be run with paper and pencil or a laptop in a small class but that gets cumbersome for a larger class. Fortunately, there are some free tools.

Here’s Hampton and Johnson describing Kiviq.us.

Kiviq.us provides an online version of the double oral auction that works on all student Internet-enabled devices, including smartphones and iPads, without requiring students or instructors to download any special software. Results can be projected on a screen for debriefing. Instructors can set key parameters. A version with price controls can be setup. The use of the experiment is free for instructors and students. Students do not have to give their email address to play.

The design is the classic market experiment for introducing students to demand and supply. Joseph (1970) makes a strong case for the benefits of the “market experiment” in teaching based on experience with high school and undergraduate students. The original experiment was created by Smith (1962).

….After a trading session, instructors can debrief showing dynamically the history of bids, asks, trades, individual attribution of bids/asks (by clicking the chart), individual total earnings, and the underlying demand and supply curves.

Modern Principles of Economics introduces the supply and demand model and Smith’s classic experiment and thus is an ideal accompaniment.

Contagion Themes

Good post from Nicholas Bagley in 2016 at the Incidental Economist.

Every disease provokes its own unique dread and its own complex public reaction, but themes recurred across outbreaks.

  1. Governments are typically unprepared, disorganized, and resistant to taking steps necessary to contain infectious diseases, especially in their early phases.
  2. Local, state, federal, and global governing bodies are apt to point fingers at one another over who’s responsible for taking action. Clear lines of authority are lacking.
  3. Calibrating the right governmental response is devilishly hard. Do too much and you squander public trust (Swine flu), do too little and people die unnecessarily (AIDS).
  4. Public officials are reluctant to publicize infections for fear of devastating the economy.
  5. Doctors rarely have good treatment options. Nursing care is often what’s needed most. Medical professionals of all kinds work themselves to the bone in the face of extraordinary danger.
  6. In the absence of an effective treatment, the public will reach for unscientific remedies.
  7. No matter what the route of transmission or the effectiveness of quarantine, there’s a desire to physically separate infected people.
  8. Victims of the disease are often thought to deserve the affliction, especially when those victims are mainly from marginalized groups.
  9. We plan, to the extent we plan at all, for the last pandemic. We don’t do enough to plan for the next one.
  10. Historical memory is short. When diseases fall from the headlines, the public forgets and preparation falters.

Not every one of those themes was present for every disease; the doughboys who died of the Spanish flu, for example, were not thought to deserve their fate. But the themes were persistent enough over time to establish a pattern.

The books we assigned were outstanding. If you want to learn about the intersection of infectious disease, history, and public health, you could do worse than to start with them:

The Advance Market Commitment

NBER: Ten years ago, donors committed $1.5 billion to a pilot Advance Market Commitment (AMC) to help purchase pneumococcal vaccine for low-income countries. The AMC aimed to encourage the development of such vaccines, ensure distribution to children in low-income countries, and pilot the AMC mechanism for possible future use. Three vaccines have been developed and more than 150 million children immunized, saving an estimated 700,000 lives. This paper reviews the economic logic behind AMCs, the experience with the pilot, and key issues for future AMCs.

That’s Kremer, Levin and Snyder. Definitely deserving of a Nobel and kudos to Bill and Melinda Gates for being early and major supporters.

All Praise the Fist Bump

Handshaking spreads germs and is a bad method of greeting. I prefer an elegant namaste but that is slightly hard to coordinate on when the other person sticks out their hand. The fist bump is a little smoother and has a greater chance of being adopted.

A study by Mela and Whitsworth in the American Journal of Infection Control found that fist bumps transferred one-quarter as much bacteria as a moderate handshake and even less compared to a strong handshake. Fist bumps are better because of lower contact times and lower contact area.

Here’s Tom Hanks showing you how it’s done.

Hat tip: Bryan Caplan for always asking for the numbers.

Who is Wealthy?

argues against comparing wealth over time:

The difficulty of measurement of wealth between different periods derives not only because of our lack of data for most of the past but from the inability to meaningfully compare wealth or consumption patterns in the past with those of today. Some economists believe that if people in the past did not have certain amenities that we have today they must have been infinitely poorer. This is what one finds in Nordhaus and DeLong’s view of historical progress as unfolfding through reduced cost of artificial lighting, the approach that Angus Maddison (in “Contours of the World Economy: 1-2030”) termed a “hallucigenic history”.

The logic of such authors is as follows. Take the example of artificial lighting or voice recording. For Julius Caesar to read a book overnight, easily move at night around his palace, or listen to the songs he liked would have required perhaps hundreds of workers (slaves) to hold the torches or sing his favorite arias all night. Even Caesar, if he were to do that night after night, might, after some time, have run out of resources (or might have provoked a rebellion among the singers). But for us the expense for a similar pleasure is very small, even trivial, say $2 per night. Consequently, some people come to the conclusion that Caesar must have had tiny wealth measured in today’s bundle of goods since a repeated small nightly expense of $2 (in today’s prices) would have eventually ruined him. Other people at Caesar’s time had obviously much less: ergo, the world today is incomparably richer than before, and people then must have felt horribly poor and deprived of all pleasurable things. (Even if you cannot feel deprived of the things you do not know exist.)

The logic seems at first reasonable even if somewhat extreme. But it is not reasonable. Let’s extend this logic, now in a different direction, from us today to the next 500 years. Suppose that in 500 years people are able to choose for their vacation between Mars, Venus, Pluto or perhaps even to go further than that. Suppose they can fly around our solar system, go to the bottom of the ocean, zip from one end of the Earth to another in a few minutes, or do lots of fun things that we cannot imagine today, no more than Caesar could have imagined that his singers’ voices could be recorded on a tiny chip and reproduced ad infinitum at almost no cost. And when we then look at Jeff Bezos’ wealth today using the consumption opportunities of the future, that wealth is likely to look to us –from the vantage point of 500 years hence- insignificant. Bezos might be rich in our own terms, but he cannot fly to Mars this weekend, no matter how much he tries.

So should we then absurdly turn around and claim that Jeff Bezos, Bill Gates et al. are poor? Clearly not.

I am baffled by the last two sentences. Bezos and Gates clearly are poor relative to people in the future who can choose to vacation on Mars. It seems absurd to me to think otherwise. Jeff Bezos has four children. Suppose one of them had cancer. If he could, do you think Bezos would hesitate for one minute to spend a billion dollars buying the medicine that will be available to an ordinary American in the year 2050? How much would Bezos pay for an extra 10 years of life? What about an extra 100? How much for a bionic eye, a dozen extra points of IQ, or freedom from Alzheimer’s disease?

Or put it the other way. How much wealthier would you have to be to want to live in 1950, 1900 or 1850? I can come up with numbers for 1950 and 1900 but I think I would prefer my income and lifestyle today to anyone’s income and lifestyle in 1850. Dentist anyone? I’d also prefer it if my wife didn’t die in childbirth.

Branko argues that comparisons of wealth across long time periods are impossible, meaningless, even “hallucinogenic.” I think he has it backwards. It’s quite difficult to compare wealth over fairly short periods. Am I wealthier than my father was at my age (he was also a professor). Maybe. Maybe not. We consume somewhat different bundles. I have Netflix and a nicer car. He had a nicer house. But am I wealthier than my grandfather? Absolutely. On either side.

Patients as Consumers in the Market for Medicine: Bedside Manner > Survival Probability

Young and Chen, 2020: Consumer-driven health care is often heralded as a new quality paradigm in medicine. However, patients-as-consumers face difficulties in judging the quality of their medical treatment. With a sample of 3,000 U.S. hospitals, we find that neither medical quality nor patient survival rates have much impact on patient satisfaction with their hospital. In contrast, patients are very sensitive to the “room and board” aspects of care that are highly visible. Quiet rooms have a larger impact on patient satisfaction than medical quality, and communication with nurses affects satisfaction far more than the hospital-level risk of dying. Hospitality experiences create a halo effect of patient goodwill, while medical excellence and patient safety do not. Moreover, when hospitals face greater competition from other hospitals, patient satisfaction is higher but medical quality is lower. Consumer-driven health care creates pressures for hospitals to be more like hotels. These findings lend broader insight into unintended consequences of marketization.

It doesn’t surprise me that consumers respond much more to nice nurses than to survival probabilities. Nice nurses are observable by patients but survival probabilities can only be estimated from sophisticated statistical models. I do wish that patients paid more attention to the outputs of sophisticated statistical models when choosing doctors and hospitals, as I think this would improve quality, but mostly they don’t. As a result, competition increases patient satisfaction but less clearly increases medical quality and medical excellence. The authors, in fact, argue that competition reduces medical quality but that part of their paper is weaker than the former and the bulk of the economic literature indicates that hospital competition also increases quality albeit not strongly and with some mixed results.

Hat tip: Kevin Lewis.

Random Critical Analysis on Health Care

The excellent Random Critical Analysis has a long blog post, really a short book, on why the conventional wisdom about health care, especially in the United States, is wrong. It’s a tour-de-force. Difficult to summarize but, as I see it, the key points are the following. (I also drawn on It’s still not the health care prices.)

1. Health care spending is well predicted, indeed caused, by income.

Notice that the United States doesn’t look unusual when income is measured at the household level, i.e. Actual Individual Consumption, which measures the value of the bundle consumed by households whether the bundle items are bought in the market or provided by governments or non-profits. (AIC also avoids some issues with GDP per capita when a country has lots of intellectual property and exports, e.g. Ireland).

2. The price of health care increases with income but at a slower rate than income.

As a result of the above:

3. The price of health care relative to income is lower in rich countries, including the United States.

Let that sink in, health care prices are lower relative to income in richer countries. Health care in the United States is cheaper relative to income than in Greece, for example.

Since spending is going up faster than income but prices are not it must be the case that quantities are also increasing with income.

4. The density of health care workers (number of workers) and intensity (what the workers do) increases with income.

RCA: Rich countries consume much more cutting edge health care technology (innovations).  For every 1% increase in real income, we find a 1-3% increase in organ transplant operations, a 1-2% increase in pacemaker and ICD implants, a 1-2% increase in the density of medical imaging/diagnostic technology, and likely similar patterns for all manner of other new technologies (e.g., insulin pumps, ADHD prescriptions, etc.).   Obviously, these indicators are just the tip of the iceberg. Still, where data of this sort are available, they tend to be highly consistent with extreme income elasticity (particularly newer, more expensive forms of health care).  In the main, costs rise because this technological change tends to requires a lot more people in hospitals and providers’ offices to deliver this increasingly complicated array of health care (surgical procedures, diagnostics, drugs, therapies, etc.).

A bottom line is that health care spending in the United States is not exceptional once we take US income into account.

RCA’s analysis is consistent with the Baumol effect and my analysis with Helland in Why Are the Prices So Damn High (we have some minor differences with RCA on physician incomes but neither of our analyses depend on that point). A big point is that RCA and Helland and I argue that the rising price sectors are not crowding out consumption of other goods. We can and are buying more of other goods even as we spend more on health care and education. Or, as RCA puts it:

…these trends indicate that the rising health share is robustly linked with a generally constant long-term increase in real consumption across essentially all other major consumption categories.

It is true that the United States has a convoluted payment system which results in absurd and enraging bills. Fixing the pricing system could generate more equity and efficiency but RCA’s analysis tells us that billions are at stake, not trillions. A corollary is that as other countries reach current US levels of income their health care spending will look more like the United States does today.

See RCA for much more.

Our Cyborg Future

The only way to beat the AIs is to join with them. Our cyborg future is well illustrated in this video from Bertolt Meyer who has an artificial arm that he has hacked to control other devices.

I am in the process of building a device (the “SynLimb”) that attaches to my arm prosthesis instead of the prosthetic hand. The SynLimb converts the electrode signals that my prosthesis picks up from my residual limb into control voltages (CV) for controlling my modular synthesizer. The SynLimb thus allows me to plug my prosthesis directly into my snythesizer so that I can control its parameters with the signals from my body that normally control the hand. For me, this feels like controlling the synth with my thoughts. I show the prototype(s), explain how we put it together and how it works, and do a little demo.

In one way this is obvious. There is very little difference between sending electrical signals from the brain to the hand and then using the hand to control the synthesizer and sending electrical signals from the brain through the artificial hand directly to the synthesizer. As Meyer notes the whole process feels very natural. The fact that it is obvious and natural will make adoption very quick.

Hat tip: John Backus

Pop Songs are Getting Sadder and Angrier

AEON: English-language popular songs have become more negative. The use of words related to negative emotions has increased by more than one third. Let’s take the example of the Billboard dataset. If we assume an average of 300 words per song, every year there are 30,000 words in the lyrics of the top-100 hits. In 1965, around 450 of these words were associated with negative emotions, whereas in 2015 their number was above 700. Meanwhile, words associated with positive emotions decreased in the same time period. There were more than 1,750 positive-emotion words in the songs of 1965, and only around 1,150 in 2015. Notice that, in absolute number, there are always more words associated with positive emotions than there are words associated with negative ones. This is a universal feature of human language, also known as the Pollyanna principle (from the flawlessly optimistic protagonist of the eponymous novel), and we would hardly expect this to reverse: what does matter, though, is the direction of the trends.

The tempo and the tonality of the top-100 Billboard songs was also examined: Billboard hits have become slower, and minor tonalities have become more frequent. Minor tonalities are perceived as gloomier with respect to major tonalities.

The authors, Acerbi and Brand, have some speculation about why the change has occurred–negative emotions transmit more easily, random drift, changes in preferences, a change in music distribution but nothing definitive. Could rap explain the differences? The study looks at the production of new music but what about the consumption? Are we listening to sadder songs or brightening things up by listening to more songs from the past? It would be interesting to know whether this is true in other languages as well.

Hat tip: Paul Kedrosky.