AlexSchell

• AlexSchell 6 Jul 2020 11:54 UTC

  4 points

  in reply to: johnswentworth’s comment on: High Stock Prices Make Sense Right Now

  even an “overvalued” stock/​bond is usually better than plain cash

  Wait, are you expecting positive total returns from stocks over the next few months? If so, this is very non-obvious from your post.

• AlexSchell 15 Jun 2020 12:03 UTC

  12 points

  on: Coron­avirus as a test-run for X-risks

  Thank you for writing this post and tracking down everyone’s stated beliefs and updates!

  I fear MNM only operated in this case because the prosocial intervention of isolating yourself also happened to be a very selfishly effective intervention. In my view, what this community failed to predict is simply that other people would, with some delay, come to the same conclusions and act as this community did, i.e. going into some degree of isolation to protect themselves. It’s a pretty embarrassing failure! I distinctly recall expecting that aggregate behavior won’t change much until the local epidemic was visibly out of control, filling up hospitals and so on, whereas I of course was going to wisely ride all this out from my apartment.

  This would explain why there was no MNM operating in most governments in Jan-Feb. It would also mean we can’t rely on MNM helping out with future risks that have a different structure than pandemics.

• AlexSchell 2 Jun 2020 10:33 UTC

  10 points

  on: Covid-19: My Cur­rent Model

  Nice post! Agree on most conclusions except I put more weight on the herd immunity threshold being not much lower than the naive compartment models imply.

  Serology data from the 1968 flu pandemic seem to rule out large effects of heterogeneity on the final attack rate. First wave seropositivity was ~35% (mostly 25-50%) with an R0 of ~1.5. R0 increased in the second wave to ~2.5, and seropositivity ended up mostly around 60-70%.

  People claiming big heterogeneity impacts seem to have focused on models over empirics. Unfortunately the range of effects implied by different ways of modeling heterogeneity is very wide, with not much to choose between models but actual epidemic data.

• AlexSchell 14 Apr 2020 4:45 UTC

  2 points

  in reply to: AlexSchell’s comment on: April Coron­avirus Open Thread

  Some very encouraging developments. There is a PCR protocol that can test 100,000 samples in a single machine run, making millions of samples per day feasible, ignoring sample collection capacity. On that front, FDA just approved (EUA, limited scope for now) a sample collection protocol relying on saliva samples rather than nasopharyngeal swabs (would mean enormous increase in sample collection capacity). The prospects for plan #1 look dramatically better.

  On plan #3, I was hoping this would work as a backup or low-tech option for poor countries but it looks like most estimates tend to put asymptomatic + presymptomatic transmission at 50%+ of all transmission, which makes this pretty limited.

• AlexSchell 13 Apr 2020 14:42 UTC

  5 points

  in reply to: AlexSchell’s comment on: April Coron­avirus Open Thread

  I was completely wrong, I don’t think their data is subject to this worry. They now have a preprint up. From supplementary methods:

  We define daily fever counts as the number of unique users per region that take multiple elevated temperature (37.7 C) readings over the past week, and then normalize these counts by the estimated number of unique users who have used the thermometer over the past year.

  So lots of repeat readings shouldn’t affect the gauge, and neither should more of their user base taking readings. Unless they are seeing a lot of new users, or lots of returning users that haven’t used the thermometer in over a year, both of which seem somewhat unlikely, their metric should be fine.

• AlexSchell 8 Apr 2020 9:39 UTC

  2 points

  on: April Coron­avirus Open Thread

  Mass testing seems like a promising brute force strategy that can keep R < 1 after lockdown, without requiring contact tracing. I’m pretty early in thinking about this but wanted to share my thoughts to encourage parallel efforts. A few possibilities (not mutually exclusive):

  1) RNA testing: If everyone is given a daily RNA test and positives are isolated, transmission will likely be very close to 0. The US is still a factor of 1000 away from doing this (for comparison, RNA testing has scaled by 400x in the last month). However it seems likely that even testing on average every 10 days could keep R < 1. Key questions: i) what frequency of testing is enough? ii) what testing throughput is feasible?

  2) Batch RNA testing: To the extent that reagents & machines rather than PPE & workers are the limiting factor in RNA test capacity, batch testing can be used, stopping the binary search at some threshold (e.g. at batch size 10). This of course results in lots of unnecessary isolation but still a small share of the population would be isolated. Key questions: i) are reagents & machines more limited than PPE & workers? ii) what’s the optimal specificity /​ stopping point?

  3) Cheap symptom-based tests: Paul Romer has pointed out that even fairly poor tests (with specificity & sensitivity much lower than RNA tests) can significantly reduce transmission without requiring a very large share of the population to be isolated. Fever (present in 85% of mild cases) and anosmia (present in 60% of mild cases) can be tested for very cheaply. Isolating everyone with fever or anosmia eliminates nearly all transmission except for fully asymptomatic transmission. The importance of fully asymptomatic transmission is still pretty uncertain (asymptomatic shedding seems to be important but probably a nontrivial fraction of “asymptomatic” would have a mild fever or anosmia), so this might need to be combined with additional measures.

• AlexSchell 6 Apr 2020 10:05 UTC

  11 points

  in reply to: Isnasene’s comment on: April Coron­avirus Open Thread

  The Kinsa data is barely even weak evidence in favor of R0 < 1. The downward trend in fever readings are confounded, likely severely, by their thermometers having to be actively used vs. being a passive wearable. It seems plausible that more people will check their temperature when they are concerned about COVID-19, and since most people are healthy this will spuriously drive average fever readings down. Plausibly the timing of increased thermometer use will coincide somewhat with shelter-in-place orders since they correlate with severity & awareness of the local outbreak.

  Their FAQ notes that they have seen 2-3x normal usage of their thermometers (this was as of March 29, they haven’t updated this part of their FAQ since) and consider this “healthcare seeking behavior” a potential driver of their trends. This has not stopped them from promoting their data to government agencies and NYT, without mentioning this or any other limitations whatsoever (at least to the NYT).

• AlexSchell 3 Apr 2020 14:09 UTC

  9 points

  in reply to: AlexSchell’s comment on: How will this re­ces­sion differ from the last two?

  Non manufacturing index just came out: 52.5, down 4.8 points. More affected than manufacturing but still in expansion. Confusing.

• AlexSchell 3 Apr 2020 13:31 UTC

  9 points

  in reply to: PeterMcCluskey’s comment on: How will this re­ces­sion differ from the last two?

  I would focus on the ISM non-manufacturing index over the manufacturing PMI since this recession is, in the short run, primarily a services recession. Non-manufacturing index will probably be hit harder and will be more indicative of Q1 GDP.

  More generally, past indicators of GDP are probably going to lose some reliability. The sectoral breakdown and rapid timing & severity of the current shock are unique enough for many historical correlations to break down. Normally less important things like survey periods will also affect monthly time series more given the rapid timing.

  Re: Q1 GDP, based on this monthly tracking, it would only take a 1.7% (non-annualized) decline in March vs February GDP to result in negative quarterly growth. Even if March is only partially affected, I’m moderately confident there will be a bigger hit. [ETA: this prediction is for revised numbers ~2 years from now, not necessarily for the first estimate of Q1 GDP. Revisions are often large, especially around recessions, and probably more so with this one.]

  What links here?

  • LW Coron­avirus Agenda Up­date 4/​6 by Elizabeth (6 Apr 2020 17:53 UTC; 24 points)

• AlexSchell 24 Mar 2020 11:53 UTC

  3 points

  on: Coron­avirus Open Thread

  This looks sketchy to say the least (e.g all citations are self citations), but seems worth doing a very shallow dive into or pointing out if clearly flawed: claim that yogurt can prevent secondary bacterial pneumonia in COVID-19 patients. The argument seems to at least imply that secondary bacterial pneumonia leading to cytokine storm is a common pathway to fatal cases.

  (H/​t Rob Wiblin on Twitter)

• AlexSchell 19 Mar 2020 16:25 UTC

  1 point

  in reply to: Jackson L’s comment on: Coron­avirus Open Thread

  Their paper is not relevant as they do not analyze testing & contact tracing AT ALL, only mentioning it briefly in the Discussion section. I think everyone who thinks the strategy I describe might be feasible (which now seems to be most informed participants in the discussion on here & rationalist Twitter) more or less agrees with the Ferguson analysis if you assume you can’t do testing & tracing & isolation or they won’t work.

• AlexSchell 19 Mar 2020 11:15 UTC

  13 points

  on: Covid-19 Points of Lev­er­age, Travel Bans and Eradication

  It looks like widespread border closures are inevitable now, and border policy will become even more visibly important if/​when community transmission is brought under control in a country (e.g. as in China today where ~100% of new cases outside Hubei are imported). So I don’t think advocating for border closures is high leverage at the moment.

  I agree that it’s super high leverage to get the public and policymakers to understand that it’s not too late for eradication (R0 < 1) through strong social distancing, and that it may be feasible to keep secondary epidemics controlled at social cost far below that of continued lockdown. [ETA: as far as I can tell there is near consensus on this point among vocal rationalists on Coronavirus Twitter, but I have seen no public official or advisor state or signal that they are looking in this direction at all.]

  An important part of that will be running the numbers on something like Taleb’s proposal or your “Basically” paragraph. Ferguson et al. got quantitative results from their model & set of assumptions, so far the response has been mostly handwaving and pointing at case studies (where we have 2 months of data and are making claims around sustainable policy on 1-2 year scale).

• AlexSchell 14 Mar 2020 11:28 UTC

  17 points

  in reply to: Scott Alexander’s comment on: Coron­avirus Open Thread

  If you first do lockdowns to get new cases to ~0 and then relax, optimistically you will get localized epidemics that you can contain with widespread testing, contact tracing, and distancing if needed. Cost of testing & tracing and having to do occasional local/​regional lockdowns could end up being manageable until treatment/​vaccine arrives.

  My main reason for optimism is Korea’s and China’s success containing a large outbreak. We will be expecting the secondary epidemics and reacting quickly, so they will be small when detected, so should be much easier to contain than the first surprise outbreak.

  We’ll get data on this in the coming months as China loosens restrictions. There is option value in containing asap and first trying things other than deliberate infections.

• AlexSchell 14 Mar 2020 8:53 UTC

  4 points

  in reply to: WilliamKiely’s comment on: Coron­avirus Open Thread

  Yeah I got better hospitalization/​ICU rates from Bucky and upped beta to 0.3 in uncontrolled scenario to make a point on Twitter. Hospital/​ICU bed availability % is graphed in each scenario tab, by overcapacity I mean the inverse of availability. Alternatively take ratio of peak to line in the Charts tab. Looks like ~15x and 5x now for hospital beds.

• AlexSchell 13 Mar 2020 20:34 UTC

  4 points

  in reply to: Original_Seeing’s comment on: Coron­avirus Open Thread

  I meant sodium hypochlorite

• AlexSchell 13 Mar 2020 6:29 UTC

  4 points

  in reply to: Bucky’s comment on: Coron­avirus Open Thread

  Thanks for digging these up! I updated the model. Still terrible.

• AlexSchell 12 Mar 2020 22:27 UTC

  2 points

  in reply to: jmh’s comment on: Coron­avirus Open Thread

  I used overall US numbers. I didn’t consider capacity expansion but also didn’t take out already-occupied beds, as I think both are roughly on the order of 2-5x in opposite directions. The only Bay Area-specific numbers are population and day 0 infected (I assumed ~10x confirmed cases).

• AlexSchell 12 Mar 2020 22:22 UTC

  4 points

  in reply to: jmh’s comment on: Coron­avirus Open Thread

  China locked down Wuhan at ~500 confirmed cases and many other Hubei cities the next day, which immediately lowered transmission (see Chart 7 here) to R0 below 1. This is very far from the uncontrolled scenario and still overloaded the health care system. This is much of the point of the post I linked—the degree of hospital overload in an uncontrolled scenario is so high that even huge reductions in transmission don’t realistically avoid overload if R0 stays above 1.

• AlexSchell 12 Mar 2020 18:27 UTC

  2 points

  in reply to: jmh’s comment on: Coron­avirus Open Thread

  I made a model that tries to replicate the chart, see here.

• AlexSchell 12 Mar 2020 18:21 UTC

  3 points

  in reply to: Original_Seeing’s comment on: Coron­avirus Open Thread

  Thanks! I didn’t realize how effective bleach is. I recently moved and didn’t get around to stocking up on any alcohol until it was out of stock in most places. I am expecting a shipment of industrial ethanol (still available, just don’t ingest/​get on your skin) but the bleach will arrive sooner. Thanks again.