
A Failure, but Not of Prediction - barry-cotter
https://slatestarcodex.com/2020/04/14/a-failure-but-not-of-prediction/
======
TheCowboy
I like a lot of what is said in this piece.

Background: I am currently supporting myself by betting on politics and
economics. I was caught jobless when this thing hit, halting my attempt at a
career switch into either coding or data science. At the end of February I
posted my first forecast for 200k cases by March 20th, giving it a 96% chance.

I feel like there exists the possibility of doing better, and there exist
people who are already there but no one wants to listen or change.

Watching this thing since the start of the year has been like watching a
preventable slow motion crash, where many people seemed to be trying their
hardest to intentionally fail.

Let's not just blame the MSM or "elites" either. I speak to people who
confidently assert everything is going to be fine in a year, and when pressed
for a probability it's not even in top quartile. Even if it was 90% certain, a
10% chance of a significantly negative outcome is too high.

I can open any thread on HN regarding economics and the general level of
arrogant ignorance is staggering. We're on target to massively screw up the
economic relief, which will make the economic stimulus phase all the more
challenging. People need to be more predisposed to having possible
intellectual and knowledge blind spots.

But I'm not all negative, as I remain very optimistic that people will
continue to ignore reasonable warnings.

~~~
roenxi
It exposes an interesting flaw in people's thinking where they hear percent
and immediately convert it to a binary (75% -> Yes, 29% -> No). If pressed
most would probably claim to understand that 75% means "every 4th time we see
this it won't work" and 29% "nearly every 3rd time it will", but in my
experience most people act more appropriately for the binary outcome than the
probabilistic one.

Thinking and acting to the probability model is almost a superpower; I keep
finding I'm ready for 1 in 10 style events that other people don't see coming.
After being told authoritatively there is a 10% chance of it happening, no
less. Eg, I will look at what a 1:100 year rain event in an area will cause
then make long term decisions around it.

~~~
tomp
_> I keep finding I'm ready for 1 in 10 style events that other people don't
see coming._

Surely if you’re ready for more than 10% of 1-in-10 events, your probabilities
are just as wrong as other people’s; it’s just that your risk management is
better.

 _That_ is why I don’t like probabilities for what are fundamentally one-off
events.

~~~
roenxi
I posted a comment saying "a common mistake is thinking 10% = No" and you've
responded by with something that looks a lot like "you're making a mistake
thinking 10% = yes".

My suggestion is you don't have enough information to claim I'm making any
specific mistake.

~~~
jodrellblank
You prepare for a 1 in 10 chance event which other people don't prepare for;
i.e. is you act exactly as if you think it will certainly happen, but you tell
yourself you don't think it will certainly happen?

This sounds like a distinction without meaning. Using "people mistake my
preparation for me believing that it will happen, so they are dumb" is weird.
You're acting as if you think it will happen, of course people think you think
it will happen. Why else would you bother preparing? You're not buying 10% of
the sandbags you'd need, you're buying 100% of them because nothing else would
do.

"Oh but I'm smarter" but your belief is leading you to take the same actions
as the person who thinks 10% == yes, so in what way is it smarter? In what way
is it _different_?

~~~
mannykannot
> so in what way is it smarter? In what way is it _different?_

As Alexander said repeatedly, it's cost-benefit analysis. See my other post in
this thread.

If you go through life only preparing for the things you are certain will
happen, you are quite likely to experience some avoidable unpleasantness.

~~~
jodrellblank
This doesn't answer my question. If you prepare for it, then you are acting as
if you think it will happen. That is, if you thought it would definitely
happen you would do the same thing you are doing now, therefore the two states
are indistinguishable except for the story in your head - and the main point
about the story seems to be "I don't think it will happen therefore I'm better
than the people who do think it will happen, even though we are both expending
the same effort, doing the same preparations, to avoid the exact same problem"

Chanting "cost benefit analysis" doesn't change anything.

~~~
roenxi
> If you prepare for it, then you are acting as if you think it will happen.

That isn't the case. Preparation isn't a binary state either - people can be
more or less prepared for an occurrence. The estimated likelihood of an event
changes how much time and effort should be spent preparing to it.

There is a big difference in how people behave if they thing there is a 0%,
0.05% or 98% chance of being mugged when they go outside for example. The
0.05% case would rationally start avoiding people late at night or not
carrying valuables. The 98% person would not go outside.

------
joe_the_user
"First, a bunch of generic smart people on Twitter who got things exactly
right... 'Bill Gates, Balaji Srinivasan, Paul Graham, Greg Cochran, Robin
Hanson, Sarah Constantin, Eliezer Yudkowsky, and Nicholas Christakis....'"

And

"...they didn’t beat the experts in epidemiology. Whatever probability of
pandemic the experts and prediction markets gave for coronavirus getting
really bad, these people didn’t necessarily give a higher probability. They
were just better at probabilistic reasoning, so they had different reactions
to the same number..."

I noticed that. As a math person, things were exceptionally clear at a point,
clearer than many uncertain events tbh. Simple exponential growth this, I can
understand ... and so could a significant slice of people.

But my question is: if epidemiologists aren't experts at THIS, wtf are they
experts in? Isn't this exactly the "classic" circumstance any average
epidemiologist should be a able to see in a heartbeat. Apparently not, so what
do they train these people in? Question maybe half rhetorical but also
serious. What's "expert knowledge" in these circumstances.

~~~
nl
_epidemiologists aren 't experts at THIS, wtf are they experts in?_

They are experts, but aren't used to rapid analysis with incomplete data.

The very early data (early-mid January) was very unclear. This is completely
normal with a new disease (just look at how the US has to rely on newspapers
and universities for national reporting numbers!)

But epidemiologists are reluctant to guess when we weren't even sure about the
transmission mechanism, how infectious it is, incubation times, or even
hospitalisation numbers (don't forget it's a respiratory disease and there was
no test available until well into January)

(Not an epidemiologist, but I've had papers published by the CDC on
epidemiology)

~~~
yxhuvud
As a bonus, they probably got burnt a bit by the bird flu nothingburger. That
will be conductive neither of them speaking up when not being certain and of
politicians listening to them.

~~~
lonelappde
Instead of bird flu being a lucky near-miss wake-up call (it spawned Contagion
which laid out the issue in an easy to digest movie format!), it became an
excuse to hit the snooze button.

~~~
nl
That's a bad take: even in the US the CDC built a bunch of knowledge and
systems ready to respond to another epidemic like bird flu. Unfortunately it
all got thrown away over the last couple of years.

Other countries that were hit by it and by SARS or MERS were ready for it.

------
mehrdadn
A bit unrelated, but I heard about this 2007 paper recently [1]:

> _The presence of a large reservoir of SARS-CoV-like viruses in horseshoe
> bats, together with the culture of eating exotic mammals in southern China,
> is a time bomb._

I know the instant reaction is "people predict things all the time, some are
bound to come out right", but this seems so specific that I think it's not
just pure chance... we're just not heeding some of the warnings.

\------

Now one reaction to the blog post: it does make a lot of good points
(especially about masks), but for the part about shutting society at least, it
doesn't seem to account for the follow-on effects of being wrong. If
governments had shut things down due to a 10% chance of a pandemic, and it was
prevented, chances are decent that a lot of not-similarly-reasoning people
would've been angry. A lot of people, some for good reason and some for bad,
just don't trust their governments (or the media) enough, and of those that
do, a fair chunk are going under a lot of hardship to comply. So they don't
just say "okay, I don't see it that way, but I trust you that this is for the
best, even if it means I can't put bread on the table for my family, so I'll
just live with the consequences and stay at home." Now I'm not really saying
this is an _excuse_ for governments/media to send poor messages, but it's an
understandable human component... surely you can't attribute everything to
irrational probabilistic reasoning?

[1]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2176051/#__sec2...](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2176051/#__sec26title)

~~~
meowface
But if every government had acted much earlier, when the probability seemed to
exceed 10%, there wouldn't have necessarily been any total shutdowns like what
we're seeing now (except for the initial containment in China). There would
still be some economic harm, but it'd be far, far less.

~~~
grahamburger
If we took those measures every time there was a 10% chance of a pandemic
would we be better off overall? Honest question I don't know the answer. It's
easy to say we should have acted sooner, but should we have also done more for
ebola, zika, SARS, MERS etc in the US as well, even though those didn't end up
having much of an impact here?

~~~
angry_octet
We had this expectation that nothing was really important enough to interrupt
international travel. Even as Hubei was put in lockdown the Chinese were
allowing their citizens to travel the globe, including direct flights from
Wuhan to international destinations, and applying extreme pressure on
countries to not restrict their entry.

Basically the system has too much delay to respond, even to a strong signal.
Even significant local deaths in the US is not strong enough to change
politics and media. If Ebola had broken out we would have had the same
problem.

I think we are stuck in a local maximum. It takes a significant push for the
system to escape oscillating back to where we are.

~~~
TeMPOraL
> _Even as Hubei was put in lockdown the Chinese were allowing their citizens
> to travel the globe, including direct flights from Wuhan to international
> destinations_

What? I remember Hubei was shut down _with_ airports, and the rest of the
world had to scramble evac flights to retrieve their citizens from the area.

~~~
angry_octet
They announced the lockdown before it was put into effect, leading to a bomb
burst of potential carriers escaping in the next 24H. Even after that,
international commercial flights were allowed to depart.

~~~
TeMPOraL
Oh, so just like everyone else.

I remember suggesting here and elsewhere that lockdowns should be announced on
the spot, and quarantines should be applied retroactively. I.e. if at 18:00
the president/prime minister gets on air and announces a lockdown, that
lockdown should be active from 18:00, and everyone coming into the country in
the 14 days before the announcement should be quarantined.

I remember being shouted down as suggesting something extremely undemocratic.
After all, the law isn't supposed to work backwards (all the cases where it
does notwithstanding).

~~~
angry_octet
At no point did I imply the Chinese were worse than anyone else at responding.
I agree, the lockdown should be immediate, and exceptions should be publically
documented -- 'incident 782: flight xyz with 10 pax was granted clearance to
land as a medical transport flight, under authority of XYZ, regional medical
coordinator'. I don't see requiring retroactive effect though -- just require
those people to confine themselves and their co-habitants, and stand by to be
contacted for contact tracing.

------
zuhayeer
‪“If you can buy an 80% chance of stopping a deadly pandemic for the cost of
having to wear some silly cloth over your face, probably that’s a good deal”‬

The reason the CDC didn’t previously recommend face masks could’ve been
because of a lack of RCT. But in order to do that, they would have had to
expose subjects to disease without face masks which wouldn’t make sense. Goes
to show there has to better ways for judging the viability of something
without resorting to a strict binary of “do or do not”

~~~
Karrot_Kream
I disagree. I think the CDC did actually perform a cross-benefit analysis on
masks during the initial segment of the outbreak. Given the not-
incontrovertible, yet positive, efficacy of masks, combined with the
implications of a PPE shortage for healthcare workers meant that there
probably was a calculated decision made to not recommend masks. Though at this
point, without some more transparency, I'm not sure what we can say about the
CDC's decisionmaking here.

~~~
roenxi
> not sure what we can say about the CDC's decisionmaking here.

We can say "gee, we should appoint more truthful bureaucrats".

It isn't a crazy guess that (for this pandemic) a useful mask for a normal
everyday person is anything that puts something in front of their face that
makes it a little harder to breath and baffles the air currents.

There may be a shortage of proven face masks but there is no shortage at all
of things that could be sewn up to cover faces and deaden air currents. The
cost is tiny vs the risk of it not working.

Officials who are more worried about preventing a response to the potential
crisis than the potential crisis _should not be in charge if there is a
potential crisis_. We want people to change their behaviors if there is a
crisis. Ideally even before the evidence in overwhelming that there is a
problem.

~~~
kd5bjo
The cost of recommending masks is that a large minority of people will decide
they need the _best_ mask to protect themselves, and buy them up thus
depriving the healthcare workers of them. Yes, in an ideal world, the entire
situation would be spelled out and only those people who are truly at higher
risk would acquire some of the limited supply of more-effective masks.

For that to work, however, requires a sense of community and level of trust in
government that has been in short supply in the US in recent years. These
factors were also in play for swine flu and the other potential pandemics the
article examined CDC rsponses for. In a crisis, officials have to base their
decisions on current conditions, not on what they should ideally be. Restoring
trust in government is extremely important, but can’t be accomplished in the
timescale necessary to be useful for this crisis.

------
mherdeg
I was more or less convinced by the discussion in mid-February at
[https://virologydownunder.com/past-time-to-tell-the-
public-i...](https://virologydownunder.com/past-time-to-tell-the-public-it-
will-probably-go-pandemic-and-we-should-all-prepare-now/) and
[https://virologydownunder.com/so-you-think-youve-about-to-
be...](https://virologydownunder.com/so-you-think-youve-about-to-be-in-a-
pandemic/) that there was a reasonable chance of needing to take some modest
steps to prepare for a pandemic.

The predictions in these blog posts about pandemic best practices were in
retrospect fairly accurate (see e.g. discussion under "Social distancing will
be important but unpleasant") and have been a pretty good guide for the first
month of major international response.

We're kind of into uncharted waters now though, and I'm wondering who else
will have accurate predictions of how the next year or two will go.

~~~
kd5bjo
> We're kind of into uncharted waters now though, and I'm wondering who else
> will have accurate predictions of how the next year or two will go.

There have been several out-of-control pandemics in human history that we can
look at. It’s true that lots of things have changed between the Bubonic plague
sweeping through Europe and now, but people are still people; there may be
some insights there. You’d have to ask a historian (I’m not one).

As different regions get this under control, I expect there to be health
screenings required for international travel. In the old days, this was
quarantine for inbound travellers, but adding a week or two to travel times is
a lot less palatable now. We now have other, faster, ways of determining if
someone is ill and I expect them to be deployed to protect areas that have
succeeded.

------
marvin
I’m sorry to say it, but the author is wrong in his central point that this
was not a failure of prediction.

> For that matter, why didn’t you post this – on Facebook, on Twitter, on the
> comments here? You could have gone down in legend

Well, I did. I started hedging against a stock market collapse on Feb. 19 and
sold half my tax-exposed holdings on Feb. 28, incurring a really painful skin-
in-the-game tax bill.

In the first week of March, I made a very alarmist post on my personal social
media profile, announcing to all my contacts a call to institute quarantines,
work-from-home, reduce public transport use, face masks in public and outlaw
crowds until control of the epidemic control was evident. This was after
reading anonymous first-hand accounts from doctors in Lombardia, following the
obvious exponential trend of spread in every country hit and watching China
shut down the economy of a meteopolis. At this point, it was clear what would
happen. Maybe not if you struggle to disregard _opinions_ that don’t match the
data, but that’s not the point.

I _never_ take these kinds of defensive or alarmist measures in times of
peace. It was a one-time thing, and I felt like a complete freak for going
against the consensus and sticking my head out among educated and respected
friends. Had the worst FOMO of my life regarding the tax bill and stock market
hedges. But I was right, I am not usually wrong and this is not a post-fact
rationalization. This was predictable in early March, at the latest.

Maybe the author is right that _society_ would have been unable to heed these
warnings, but that’s practically a tautology, given that we know how things
played out in most Western countries.

My family heeded my warnings, and stayed safe through the most critical phase
when the disease was rampant but not obvious.

~~~
lonelappde
> My family heeded my warnings, and stayed safe through the most critical
> phase when the disease was rampant but not obvious.

The vast majority of people "stayed safe" through the most critical phase,
regardless of behavior. even a million infections in USA is statistically
almost no one.

It's an exponential process and the world is big, and still now, deep into the
disaster, most people haven't developed symptoms.

~~~
marvin
I have family in their 70s with asthma in the south-east of France, near
Italy. They were warned in the range of dates I mention here, at a time when
their authorities encouraged them to go out and vote during a rampant, poorly
acknowledged epidemic for which the healthcare system was unprepared. A
culture where friends and strangers kiss on the cheek twice at every meeting.

You've got a point regarding the population in general, and the sentence
you're pointing at is peripheral to my point. But I have caused a significant
decrease of risk of a catastrophic outcome to some people dear to me.

They likely would have been okay. But "likely" doesn't cut it when the cost of
defensive measures are low and the result of being unlucky is permanent loss
of health or death.

------
jajag
I thought this was an excellent article, particularly the point about how and
(possibly) why the CDC advised against the use of face masks to limit spread
of infection during a pandemic. There seems to have been other failings of
expert advice in the early days of the pandemic (e.g. see the UK government's
apparent change of strategy early on) and they do to me look like failures in
academic reasoning, rather than failures of political decision making. Will be
interesting to read the findings of the inevitable inquiries after the dust
has settled.

~~~
tonyedgecombe
I find it hard to criticise the UK government on that U-turn. The facts
changed and they reacted. Prior to this starting a flu-like pandemic was at
the top of the governments risk register and they had models and a plan which
they started following.

There was some initial idiocy of course, like Boris shaking hands with
everybody in a hospital he visited.

They should probably be criticised more for their general preparedness and
tight health care spending in the face of an ageing population.

------
mrfusion
Another benefit to thinking in probabilities is that you don’t get as attached
to ideas. You don’t feel the need to defend your Opinion past it’s expiration
date. People can have better discussions without getting offended.

~~~
lonelappde
Otoh probabilities are hard to check for correctnessso you can weaael out of
being wrong by making everything you say a motte-bailey deception (to use a
slatestarcodex term).

~~~
TeMPOraL
That's why it's important to be precise in describing what you mean (which may
involve explaining the intended meaning when using a common word), so that you
can't back-track on it later. Conversely, when you see someone not doing that,
be prepared for the possibility of weaseling out.

------
greendave
It's nice to read a well-thought-out piece that both critiques and enlightens.

That said, I do think it bears some mention that a substantial amount of the
early Coronavirus discussion was being poisoned by people who were not arguing
in good faith. That sucked a fair amount of the oxygen out of the debate, and
I suspect may have left journalists in less of a position to provide
thoughtful context around expert opinions. In other words, flat earthers
occupying enough print and mindshare to make it hard to focus on the
subtleties of Keplerian motion.

~~~
cma
Sort of like how Trump’s China travel ban announcement was accompanied by a
statement saying he wanted to close the Mexican border right away too but they
decided against it. Almost to bait the media into accusing him of using the
situation for his own ends.

------
throwaway_pdp09
> Predicting the coronavirus was equally hard

No, it's mainly not. The problem is people assume tomorrow is going to be like
today and yesterday (for all problems, not just this one). Add to that that
people don't like hearing unpleasant news and will tune it out. Net result:
they ignore it and when pushed will start to deny it. You can add on top that
rare newspaper editors that do recognise a risk will not want to piss off
their readership by telling them the truth (or a or probably future
occurrence) that they will get angry at. Give the people what they want, not
what they need.

For covid, I started stockpiling a bit of food etc. about a month before
anyone else. My calculation was, this is likely to happen but may not. If
things kick off I may need it. If they don't, I eat it anyway. There's no
downside. (Incidentally I did the same ~2007 before the crash for the same
reason. Turned out unnecessary then).

What happened when I told people about covid usually follows 2 particular
patterns 1) "No don't be stupid, it's not that bad" \- simple denial. 2) they
stare at you full-face on, totally expressionless for about 2 or 3 seconds,
they turn their head away, exhale, turn back and start talking about something
else as if what you'd said never happened - blanking it. It's a curious, quite
consistent response when it happens.

We get all the warning we need, the majority of people just don't want to
know. QV. climate change, carrington events, epidemics (we had plenty of
epidemiologists saying When not If), financial crashes. It's all there if you
want to know.

------
projektfu
Sometimes you need to answer the question, what would you pay for that lottery
ticket? Sometimes you need to answer, would you pay Russian roulette with that
gun? In this case if you had a 90% confidence that Coronavirus wouldn’t escape
China or wouldn’t cause catastrophe if it did, then you still have to point
that 10-chambered revolver at your head if you choose “don’t prepare”. But
buying your way out of the game has a cost, too.

------
jonhohle
A major issue, not just with the current pandemic, but all major network news
programs, is they are not news, they are entertainment editorials. However,
they don’t present themselves as such, and present information as if absolute
and unbiased.

If there were journalistic standards and not just first to print clickbait,
there would have to be nearly as many corrections and retractions as there are
news stories.

The constitution guarantees freedom to publish, but it would be really nice
into have some legal standard for accurate reporting of current events in good
faith.

~~~
disgruntledphd2
You could call it a fairness doctrine, or something ;)

[https://en.wikipedia.org/wiki/FCC_fairness_doctrine](https://en.wikipedia.org/wiki/FCC_fairness_doctrine)

------
armitron
Not even a mention for Taleb who had a paper out in January [1] yet paragraphs
for Zeynep and the rest who merely parroted rising consensus?

Weak, very weak.

[1] [https://necsi.edu/systemic-risk-of-pandemic-via-novel-
pathog...](https://necsi.edu/systemic-risk-of-pandemic-via-novel-pathogens-
coronavirus-a-note)

------
SergeAx
IMO it was not about prediction per se, it was about prediction of magnitude.
Will be Wuhan virus bad? Probably so. HOW BAD will it be? That's just another
level of prediction.

Remember that experiment with smoke in the room with actors sitting and
chatting like this is totally fine? [0] Posting a tweet "I am getting ready to
3-6 months quarantine and advise everybody to do so as well" has much more
internal pressure.

[0]
[http://www.weirduniverse.net/blog/comments/the_smoke_filled_...](http://www.weirduniverse.net/blog/comments/the_smoke_filled_room)

~~~
Smaug123
Indeed, Putanumonit used precisely that analogy in
[https://putanumonit.com/2020/02/27/seeing-the-
smoke/](https://putanumonit.com/2020/02/27/seeing-the-smoke/) .

------
ilkan
IMHO, the journalists' mistake was lazily relying on easily accessible Western
orgs instead of partnering with Eastern-based journalists to examine stories
coming out of China. I've been following the South China Morning Post since
the first week of January and so far all the observations coming from their
experts has been refuted by the CDC first, then confirmed a month or two
later. They are just as smart, highly motivated and had at least 10x more
casework to examine. Tldr; if you want to make better predictions, compare
expert opinion against news closer to the source.

------
angry_octet
It is astounding how much D-K this piece exhibits. On what basis does he think
that virus-transmissive mask wearing is effective? Absolutely none. (He
doesn't mention equally plausible arguments about why it could be worse.) And
then he goes on to mis-comprehend the parachute study, and predictably use it
to justify doing not what experts recommend, but what non-experts want to
believe.

Also he really seems to mis-comprehend probability and confidence intervals --
like most people. A 29% chance of Trump winning should have been a five alarm
alert that there was a significant chance of catastrophy -- even for
Republicans. But we're too focused on the things that are very likely. (Like
death, and as an American prelude, bankruptcy from health costs, being screwed
by megacorps, taxes, and rich getting unfair tax breaks.) If car accidents
weren't common and easily foreseeable, would we have insurance? Only if part
of the system made us, based on risk analysis.

~~~
ddxxdd
>On what basis does he think that virus-transmissive mask wearing is
effective?

His prior post has already proven this beyond a shadow of a doubt.

[https://slatestarcodex.com/2020/03/23/face-masks-much-
more-t...](https://slatestarcodex.com/2020/03/23/face-masks-much-more-than-
you-wanted-to-know/)

Perhaps that post is a prerequisite to this post.

~~~
angry_octet
Well, we have different concepts of doubt. Also, he's talking about proper
procedure masks (ASTM Level 1), not paper or cloth or home made masks. These
are hard to come by, and in any case should be reserved for high risk
situations. There are no studies that I can find showing woven fibre or paper
mask effectiveness, especially in regards to the risk increased contact
transmission from touching the mask.

~~~
ddxxdd
>There are no studies that I can find showing woven fibre or paper mask
effectiveness

Oh, well you're in luck. I have just the thing for you:

[https://smartairfilters.com/en/blog/best-materials-make-
diy-...](https://smartairfilters.com/en/blog/best-materials-make-diy-face-
mask-virus/)

This image is the quick, all-encompassing money-shot:
[https://smartairfilters.com/wordpress/wp-
content/uploads/202...](https://smartairfilters.com/wordpress/wp-
content/uploads/2020/03/Mask-Materials-Effectiveness-1-Micron-EN-768x558.jpg)

You can make the argument that homemade masks won't reach those levels of
effectiveness because of a lack of a strong seal around the airways. And there
have been no real-world case studies of cotton masks protecting people from
getting sick.

But there are plenty of arguments to be made that support the idea that if
100% of the population wore a cotton shirt around their face, then the
pandemic would be strongly mitigated.

------
User23
> The stock market is a giant coordinated attempt to predict the economy

This statement is so obviously and absurdly wrong it makes it difficult to
appreciate the rest of the article.

~~~
nil-sec
Could you elaborate why you think that? It isn’t obvious to me why this is
absurdly wrong.

~~~
User23
The stock market and the economy are observably decoupled. I’m a trader by
profession and if I traded based on the real economy rather than, say, the
Fed’s latest shenanigans, I’d be ruined in a heartbeat. Just this past month
we’ve seen the most crippling blow to the real economy in over a century and a
massive stock market rally.

~~~
nil-sec
Okay, but in this case a better assumption seems to be, the stock market is a
function of the economy and political interventions. Or would you suggest this
function does not depend on the economy at all?

~~~
User23
I wont't say that the stock market doesn't depend on the economy at all,
because that's also obviously incorrect. A total economic collapse (think
dollars stop being worth money) would obviously affect the stock market just
to list a limit case. But on the margins, no, the economy doesn't move the
stock market in any appreciable fashion in the time frame a trader operates.
In the extremely long term though the health of US capital markets is a
function of the size and broad diversification of the US economy.

Operationally speaking, the market moves based on the actions of market
participants and thus the primary intellectual challenge is predicting those
actions. Since currently the Federal Reserve working in concert with the US
Treasury is an active market participant with unlimited capitalization that is
telegraphing its moves, that is what's moving the market. Literally nobody
trades on the reality that thousands of small businesses are in danger of
going bust. Personally I think it's awful, but I don't have the capital to fix
it.

------
danbmil99
Nate silver is a god. When everyone else was massaging their predictions to
get them under 5% for Trump, he stuck to his guns. I have a strong suspicion
that if we could run the counterfactual, 29% would be right on the money.

~~~
disgruntledphd2
I am honestly more impressed by his original work, building multi-level models
for Bush vs Obama. There was a kind of earnestness to his coverage that's been
lost (inevitably) since he, and 538, became such a big brand.

------
thaumaturgy
There's some shockingly bad thinking in this article and I'm surprised that
people seem to be taking it at face value. Picking just a few things that
stood out to me:

> _First, a bunch of generic smart people on Twitter who got things exactly
> right – there are too many of these people to name, but Scott Aaronson
> highlights “Bill Gates, Balaji Srinivasan, Paul Graham, Greg Cochran, Robin
> Hanson, Sarah Constantin, Eliezer Yudkowsky, and Nicholas Christakis.”_

This is pretty much the definition of cherry-picking. How many equally smart
people got it wrong? Was there something in common among these particular
people that led them to get it right, or did they hazard a guess on
approximately the same information that everyone else had and then end up in
the winning group?

There's a fun article somewhere in my bookmarks that I can't find right now,
but it covers the phenomenon of some bettor -- at the race track, or the stock
market, or something -- who has this crazy winning streak and nobody can
figure out why. Maybe it's this person's lucky hat, or maybe it's the notes
they take, or maybe... who knows. But the most compelling reason is that they
just happen to be the 1 member of a very large group who, through probability
alone, keeps winning.

This other article sort of mentions it in passing:

> _The prosecution also had an expert witness, an economist named David
> DeRosa. He didn’t share Heeb’s views about poker. DeRosa used a computer to
> simulate what might happen if 1,000 people each tossed a coin 10,000 times,
> assuming a certain outcome — such as tails — was equivalent to a win and the
> number of times a particular person won the toss was random. But the results
> were remarkably similar to those Heeb presented: A handful of people
> appeared to win consistently, and another group seemed to lose a large
> number of times. This wasn’t evidence that a coin toss involved skill, just
> that — much like the infinite number of monkeys typing — unlikely events can
> happen if we look at a large enough group._

([https://www.discovermagazine.com/the-sciences/are-the-
best-g...](https://www.discovermagazine.com/the-sciences/are-the-best-
gamblers-skilled-or-just-lucky))

Back to the posted article...

> _parachutes, etc. etc._

I mean, all kidding aside, there are enough parachute failures at this point
to have a pretty good idea of the grim odds of surviving a fall from an
aircraft without one.

There are some really good reasons for conservativism in medicine. We have
lost many, many lives to cures, treatments, and preventions that were "common
sense" and only later discovered to be wrong. Or, sometimes, work, but only
accidentally. Scurvy is the historical go-to example here. Its cause and
treatment has been discovered, lost, and rediscovered many times, and each
time, there was some common-sense treatment for it that was wrong.

> _Gallant wouldn’t have waited for proof. He would have checked prediction
> markets and asked top experts for probabilistic judgments. If he heard
> numbers like 10 or 20 percent, he would have done a cost-benefit analysis
> and found that putting some tough measures into place, like quarantine and
> social distancing, would be worthwhile if they had a 10 or 20 percent chance
> of averting catastrophe._

Gallant will spend his life preparing for the next disaster that has a 20%
chance of occurring and will eventually end up living in a small off-the-grid
cabin deep in the woods, slowly being poisoned by the well water that isn't
being tested correctly or often enough.

There is an opportunity cost for preparing for disaster. I'm all for being at
least a little bit prepared. My favorite hobby involves going out and
retrieving people who were unprepared. But I _never_ criticize them for
getting into bad situations, because it can happen to any of us. (With the
possible exception of people who don't evacuate from hurricane areas. Those
people piss me off.)

You can't prepare for everything. Most of us have never lived through a
situation like we're living through now. How believable would this all have
been a year ago? Who could believe that we'd be willing to stop the _world
economy_ because of a virus?

The irritating nut of this is that this isn't necessarily something you can
learn from. Okay, let's say you're one of the people that did the mental math
and chose not to react -- a "Goofus", according to this article. So you learn
from it, yeah? Next thing comes along with a 10% or 20% chance, you prepare
for it. You're in California, so, earthquake: you fill up your garage with
supplies. The earthquake never comes. Then there's a 10% or 20% chance of
wildfire destroying your community... so you move, except the wildfire never
hits that community. Armed robbery. Disease. Storms. All of these have some
kind of low probability of happening, but will have super serious consequences
if they do, so you -- remembering covid-19 -- prepare for each of them.
Decades come and go, and eventually, you decide, hey, you're busy. You can't
really deal with that thing right now. And besides, none of the others have
happened. Except, this time the floods do come, and you're screwed again, and
now some guy is writing about how all those people who didn't properly prepare
for the flood had bad mental models for assessing risk.

> _A few weeks ago, I wrote a blog post on face masks. It reviewed the
> evidence and found that they probably helped prevent the spread of disease.
> Then it asked: how did the WHO, CDC, etc get this so wrong?_

Absent from the blog post he references is that there's uncertainty over
whether face masks might actually _increase_ the risk of infection among
healthy populations of non-medical professionals. The thinking goes that some
number of people don't know how to properly use the masks (which he covers)
and that they end up touching their face _more_ as a result, and that the
masks that most people are using aren't great filters for this particular
virus, so the net change in probability of getting infected is going up.

But this isn't a certainty. There isn't enough data to know for sure if this
is true or not. Even after this pandemic runs its course, there will probably
still be disagreement in the studies to come because of all the confounding
factors at play.

It's a reasonable position though, and that's why people keep getting
conflicting information on this. You can get some treatment of the debate and
confusion around this from this discussion:
[https://old.reddit.com/r/COVID19/comments/fcwcn7/to_mask_or_...](https://old.reddit.com/r/COVID19/comments/fcwcn7/to_mask_or_not_to_mask_the_seemingly_endless/)
...people are posting studies supporting one position, then rebutting them,
then offering professional advice in one direction, and then others in
another. It's a mess, and while that thread isn't rigorously scientific,
essentially the same argument is happening at and between the CDC and WHO and
others.

~~~
bounded_agent
Mm, most of this seems well-intentioned but a bit confused to me. I might
specify the easiest point that's mistaken as this bit:

> So you learn from it, yeah? Next thing comes along with a 10% or 20% chance,
> you prepare for it. You're in California, so, earthquake: you fill up your
> garage with supplies. The earthquake never comes. Then there's a 10% or 20%
> chance of wildfire destroying your community... so you move, except the
> wildfire never hits that community. Armed robbery. Disease. Storms. All of
> these have some kind of low probability of happening, but will have super
> serious consequences if they do, so you -- remembering covid-19 -- prepare
> for each of them.

In the last decade of living in Berkeley, me and my nearest ~150
friends+acquaintances have not experienced a wildfire destroying our
community, an earthquake causing life-threatening damage, armed robbery (a few
muggings, but less of us have been affected by 10-100x as are affected by
covid), storms causing life-threatening damage, etc. So the probability of all
of these cannot be 10% in a given couple-of-months period (as we did to Covid
in Feb), because they would all have happened like a dozen times in the last
decade if so.

10% is just really, really high, relative to the baseline for life-shattering
catastrophes. I've seen journalists say "We can't talk about all the 10%
catastrophes, we'd look alarmist!" The level of threat that Covid was in mid
February was just not comparable to the tragedies you listed above, it was a
straightforward exponential growth in a fairly severe disease happening in
many countries. You can argue that at the time I (or professional
epidemiologists or whoever) should've assigned it the sort of low probability
(<1%) associated with things like armed robbery and wildfire hitting me in
Downtown Berkeley, but I think you'd be wrong, there just weren't that level
of strong arguments about the baseline safety. It was a real risk, and it was
correct to prepare in late Feb (as I did, and self-quarantined as soon as the
first Berkeley case was reported in early March).

I just wanted to rebut the thing that seemed most wrong to me. I hope you're
well in this difficult time.

~~~
lonelappde
> I've seen journalists say "We can't talk about all the 10% catastrophes,
> we'd look alarmist!"

Alarmism is the bread and butter of journalism. Media consensus was that
electing Trump was supposed have led to invading Poland and gassing minorities
by now.

