The Wisdom of the Inner Crowd
Abstract: Many decisions rest upon people’s ability to make estimates of some unknown quantities. In these judgments, the aggregate estimate of the group is often more accurate than most individual estimates. Remarkably, similar principles apply when aggregating multiple estimates made by the same person – a phenomenon known as the “wisdom of the inner crowd”. The potential contained in such an intervention is enormous and a key challenge is to identify strategies that improve the accuracy of people’s aggregate estimates. Here, we propose the following strategy: combine people’s first estimate with their second estimate made from the perspective of a person they often disagree with. In five pre-registered experiments (total N = 6425, with more than 53,000 estimates), we find that such a strategy produces highly accurate inner crowds (as compared to when people simply make a second guess, or when a second estimate is made from the perspective of someone they often agree with). In explaining its accuracy, we find that taking a disagreeing perspective prompts people to consider and adopt second estimates they normally would not consider as viable option, resulting in first- and second estimates that are highly diverse (and by extension more accurate when aggregated). However, this strategy backfires in situations where second estimates are likely to be made in the wrong direction. Our results suggest that disagreement, often highlighted for its negative impact, can be a powerful tool in producing accurate judgments.
From a paper by Van de Calseyde and Efendić.
What this means is that diversity can improve group thinking but you need cognitive diversity, i.e. you need people in the group who disagree with one another not people who all agree despite superficial differences.
Another simple tool to make judgment more accurate is the premortem.
Hat tip: The excellent Steve Stewart-Williams.
Uncertainty and the import of norm adherence
The cabinet agreed the measures during an emergency Zoom meeting after being presented with data that showed the NHS would run out of bed capacity by the first week in December.
That is from the London Times, and it is the government’s rationale for a new and very strict lockdown plan. Once you are in this position, there are truly no good choices, nor will you succeed in “protecting the vulnerable” under any of the paths before you.
But let’s turn the clock back a wee bit, shall we say to Liverpool, circa July 2020. At that point, in the “clubby” part of town, drunken youths were walking around, arm-in-arm, serenading each other and singing. Without masks. Barber shops were full, the barbers are wearing plastic visors (often no masks, and it seems the visors are less effective) and many of the patrons were wearing no masks. Overall the mask-wearing rate did not seem to exceed ten percent, if that. People on the (closed window) trains to and from Liverpool often did not have masks, and they were gabbing rather than silent. Few natives were looking aghast at any of this. And unlike in London and parts of southeast England, there was no plausible reason whatsoever to believe in herd immunity for Liverpool.
The recommendation is simply that Liverpool and most or all other parts of England needed stronger norms back then. To stop later severe lockdowns.
And here is Max Roser on testing.
If someone talks about “protecting the vulnerable,” ask a simple follow-up question: how much are they also talking about masks and testing (and biomedical advances)?
You can argue about exactly how effective masks are, or how much the current Covid return is a purely seasonal effect, or what about Peltzman effects (mask wearers will take more risks), and so on. There is typically uncertainty about just how strong norms will be in their final effects, but that is not reason to toss out those norms.
But if people aren’t even trying, you know something is very, very wrong. Blame the elites. Blame the people themselves. Those two alternatives are not nearly as distinct as they might seem.
And I am not asking for the impossible or for the totalitarian. Liverpudlians and the now on the run cohorts of Europeans would be much better off if they had only matched the rather ragged norms and safety record of my own northern Virginia, which is full of immigrants I might add. People here made many mistakes, but on the whole never became altogether negligent.
Europe is seeing a major second wave of its current magnitude because, in so many places, people simply stopped trying. With vaccines on the way, those were indeed grave errors.
Sunday assorted links
1. “Scrutiny of this proposition through the lens of rational choice theory suggests, however, that exorcism was inferior to executions as a technology choice for the congregant-maximizing Puritan ministers in Salem Village in 1692.” Link here.
2. Good Ross column! (NYT)
4. Economists give reasons why they voted. What do you think?
5. Is this true?: “Iran bypassing American sanctions by nationalizing cryptocurrency miners. A new regulation requires miners to sell their coins directly to the Iranian central bank for use to fund imports.”
6. Bruno and his substack on Islam, good piece.
*Kindred: Neanderthal Life, Love, Death and Art*
By Rebecca Wragg Sykes, an excellent book, a very responsible treatment of what we do and do not know about Neanderthals, with a bit on Denisovans as well. It is a book full of sentences such as: “Micro-morphology has also provided proof that, far from being slovenly, Neanderthals were regularly disposing of their rubbish.” It seems they enjoyed mussels and also grubs, among many other foodstuffs. The hearth was the center of the home and they had fairly advanced systems for butchery. They used leather and deployed pigments.
I enjoyed this segment:
Parisians, Londoners or Berliners today with ostensibly European heritage have very little connection even to Mesolithic people just 10,000 years ago. The vast majority of their DNA comes from a massive influx of Western Asian peoples during the Neolithic. This means that many of the first H. sapiens populations are more extinct than the neanderthals; not a great sign of evolutionary dominance.
Recommended, you can order here.
Micro-hemorrhages and the importance of vaccination
Neurological manifestations are a significant complication of coronavirus infection disease-19 (COVID-19). Understanding how COVID-19 contributes to neurological disease is needed for appropriate treatment of infected patients, as well as in initiating relevant follow-up care after recovery. Investigation of autopsied brain tissue has been key to advancing our understanding of the neuropathogenesis of a large number of infectious and non-infectious diseases affecting the central nervous system (CNS). Due to the highly infectious nature of the etiologic agent of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is a paucity of tissues available for comprehensive investigation. Here, we show for the first time, microhemorrhages and neuropathology that is consistent with hypoxic injury in SARS-CoV-2 infected non-human primates (NHPs). Importantly, this was seen among infected animals that did not develop severe respiratory disease. This finding underscores the importance of vaccinating against SARS-CoV-2, even among populations that have a reduced risk for developing of severe disease, to prevent long-term or permanent neurological sequelae. Sparse virus was detected in brain endothelial cells but did not associate with the severity of CNS injury. We anticipate our findings will advance our current understanding of the neuropathogenesis of SARS-CoV-2 infection and demonstrate SARS-CoV-2 infected NHPs are a highly relevant animal model for investigating COVID-19 neuropathogenesis among human subjects.
That is from new Fast Grants supported research by Tracy Fischer, et.al. And here are some related earlier results from Kabbani and Olds. Here are some more general recent results about brain damage.
How bad are these micro-hemorrhages anyway? I don’t know! You may notice I have hardly lunged at the “permanent damage” papers that have been coming out on Covid (in fact many of them already have collapsed or not replicated). But there are genuine reasons for caution, these results do not seem to be collapsing, and Covid-19 is not just a bunch of people trying to make a mountain out of a molehill. And “exposing the young” decisions should not be taken lightly either. The people who are very cautious about reopening may be too risk-averse given realistic alternatives, but they are not all just statists, Trump haters, lazy teachers’ unions, and so on. There are very genuine concerns here.
New results on vaccine-mask interaction
However, if face mask use is reduced by 50%, a vaccine that is only 50% effective (weak vaccine) would require coverage of 55-94% to suppress the epidemic in these states [CA, NY, TX, FL]. A vaccine that is 80% effective (moderate vaccine) would only require 32-57% coverage to suppress the epidemic. In contrast, if face mask usage stops completely, a weak vaccine would not suppress the epidemic, and further major outbreaks would occur. A moderate vaccine with coverage of 48-78% or a strong vaccine (100% effective) with coverage of 33-58% would be required to suppress the epidemic.
That is from a new paper by Mingwang Shen, et.al., via Alan Goldhammer.
As for the European lockdowns currently under way, I do not know which choices those nations should be making. The British one, which I know the most about, seems far too strict to me. No matter what your exact point of view, surely there is something to David Conn’s comment:
Government gone from spending £500m paying people to eat out, to closing all the restaurants, in 2 months.
In any case, if those nations had continued (or in some cases initiated) widespread mask use, they would be facing much, much better trade-offs today.
Saturday assorted links
1. Can black holes shed information?
2. “Ancient dogs were much more diverse genetically than modern dogs.” And Finnish Covid-sniffing dogs doing just fine.
3. Admissions pauses and reductions in Harvard graduate programs?
5. When Paul McCartney met Bertrand Russell.
6. Stanford/Hoover disputes over Covid freedom of speech. How is this for Orwellian doublespeak: “There are limitations to academic freedom. What you express has to be honest, data-based and reflect what is known in the field. If you are going to claim academic freedom, you had better be academic, as well as free.”
Vitalik Buterin’s Conversation with me
He is interviewing me, and yes he does close with a bout of Overrated vs. Underrated. Here is the YouTube link, it starts at about 7:00, give or take a few seconds. I thought it was very interesting, on both of our sides, more of a dialogue than an interview, the points of focus being crypto and tech utopianism.
Perhaps the next time we will get to The New Monetary Economics…
What housing bubble was that again?
Value of housing market at all time high: Home equity has driven up value of US houses since 2012 to a current record value of $32.8 trillion ($11.3 trillion debt, $21.5 trillion equity) 28% higher than the pre-crisis peak in 2006
That is from David Wessel on Twitter, here is the cited research. Of course there were local housing bubbles in Las Vegas, Orlando, and so on, but was there really a national housing bubble? Was not the real problem an “anti-bubble” of panic in 2007-2008? I believe Alex T. was the first to raise this point, and he remains underappreciated for this observation.
Wessel himself wrote in 2008: “We had a housing bubble; that’s now obvious.” Scott Sumner, telephone!
New books needed on the NIH and NSF
A reader writes —
“Despite being the preeminent model for global science funding, and far more powerful than any single university, the workings of the NIH or NSF are surprisingly opaque to most people. These bodies shape who becomes a scientist, what science they pursue, and how they pursue it. I would therefore like to fund a book about how the institutions of US science actually operate, how they’ve changed, what the relevant surrounding incentives are, and how it is that they should likely evolve from here. It’s possible, perhaps even very likely, that a good version of this book would be picked up by a good publisher. Even if it isn’t, it should exist in the public domain. I will invest generously in anyone who seeks to write one.”
This reader is highly credible. If you’re interested and have relevant expertise, please email me. (Suggestions for good possible authors — people who genuinely understand the system but who could be sufficiently objective and where relevant critical — are welcome although not as useful.)
Those old and new service sector jobs
In case you thought Cambridge ceremonies were just for the tourists: the porters in my college have been delivering food to self-isolating students & announcing their arrival with an actual plague bell
Here is the link, via John Chilton and Irwin Collier.
Friday assorted links
Christina Romer!
Christina Romer is excellent in this video on her work and influence. Obama had a great line. When Romer, clearly upset, told Obama that the economy was much worse than expected and heading downwards he replied, “Christy, it’s not your fault….yet.”
An interesting tension in Romer’s work. Her early work suggests that macroeconomic policy has not done much to stabilize the economy. Yet her later work has been in trying to stabilize the economy!
Rational Criminals, Irrational Lawmakers
Columnist Phil Matier writes in the SFChroncile about rampant, brazen shoplifting in San Francisco.
After months of seeing its shelves repeatedly cleaned out by brazen shoplifters, the Walgreens at Van Ness and Eddy in San Francisco is getting ready to close.
…“All of us knew it was coming. Whenever we go in there, they always have problems with shoplifters, ” said longtime customer Sebastian Luke, who lives a block away and is a frequent customer who has been posting photos of the thefts for months. The other day, Luke photographed a man casually clearing a couple of shelves and placing the goods into a backpack.
Most of the remaining products were locked behind plastic theft guards, which have become increasingly common at drugstores in recent years.
But at Van Ness Avenue and Eddy Street, even the jugs of clothing detergent on display were looped with locked anti-theft cables.
When a clerk was asked where all the goods had gone, he said, “Go ask the people in the alleys, they have it all.”
No sooner had the clerk spoken than a man wearing a virus mask walked in, emptied two shelves of snacks into a bag, then headed back for the door. As he walked past the checkout line, a customer called out, “Sure you don’t want a drink with that?”
…Under California law, theft of less than $950 in goods is treated as a nonviolent misdemeanor. The maximum sentence for petty theft is six months in county jail. But most of the time the suspect is released with conditions attached.
Some stores have hired private security firms or off-duty police officers to deter would-be thieves. But security is expensive and can cost upward of $1,000 a day. Add in the losses from theft, and the cost of doing business can become too high for a store to stay open.
Perhaps San Francisco helps us with Tyler’s “solve for the Seattle Equilibrium” challenge.
Novid — a pre-exposure notification system for Covid (and other things)
I find the (short) video easiest to follow:
https://www.youtube.com/watch?v=WN-dw-45Cwc
Best of all, it is incentive-compatible. The founder Po-Shen Loh, a mathematician from Carnegie Mellon, wrote to me:
…for each positive case, don’t just ask the direct contacts to quarantine; instead, tell everyone how many relationships away COVID just struck (e.g., “3” is a contact of a contact of a contact). Then animate this over time like a weather radar…Keep everything anonymous.
Suddenly, the main purpose of the intervention is no longer to protect others from you (quarantining after being exposed). Instead, it is to directly protect you from others, because that early warning of approaching COVID lets you know it’s a good time to wear a better mask, or to be more vigilant about distancing, because the situation is getting hot. This appeals to self-protection instincts instead of altruistic instincts. Since this app is already in deployment, we know anecdotally, for example, of a person who installed the app because his kid was going to a university that was using the app. Why? So that he could be alerted in case COVID started spreading his way from the university via his kid.
Here is his associated preprint. As economists, ought we not to feel that appealing to self-interest and love of family sometimes works?