How is coronaplague down in Brazil? (and the rest of the IHME predictions)

by philg

Yesterday was August 4, 2020, the date on which the IMHE prophecies were supposed to be proven out. Let’s see how the reality compared to the June 10 prediction. In “Wicked Brazilians will take the place of the wicked Swedes in forecasts of doom?” (June 13) I noted that 5,248 Brazilians were forecast to be killed by Covid-19 yesterday.

What does WHO say about the actual number? It was 541 yesterday (August 4), 1,088 the day before (August 3), 1,212 on Sunday, August 2, 1,129 on Saturday, August 1., and 1,595 on July 31. Here’s my prediction in full:

My perspective is a “scientific” one. In other words, I will look at one or two data points and then extrapolate wildly. From the chart below, it looks like the non-virtuous Brazilians have, by dint of doing nothing, already “flattened the curve” to a large extent. So my first scientific observation (i.e., guess) is that the death rate on August 4, 2020 will be roughly the same as it is today. On the other hand, the virus has already killed a lot of the easiest-to-kill Brazilians. Therefore, the number should be a little lower. On the third hand, General Winter is fighting alongside the coronavirus in parts of Brazil. If the latter two factors cancel out, the number of deaths tagged to Covid-19 in Brazil on August 4 should be 1,274 (the number from yesterday’s WHO report).

Summary of the above: prediction of a plateau and therefore 1,274 deaths yesterday. So I’m off by more than 2X for the actual number, but the latest graph from IHME (a smoothed curve) does look vaguely plateau-esque, so perhaps I can claim victory on the shape?

Alex guessed 1,219 following YouYang Gu’s model. ajm did an interesting analysis starting from the Diamond Princess data and came up with 1,800. Henry went with IHME, but cut their 5,248 estimate by 50 percent due to his faith in the Sacrament of Masks. Sig came up with a technical analysis approach, as they say on Wall Street:

I think the pattern is quite clear here: after the peak it is a log-linear descent, with always the same slope. No need for science or following news… (Italy has a step there, they probably transitioned to a different counting method.) So, extrapolating for Brazil, which looks like being at the peak, to 130 days, which would be beginning of August in that case, and adjust for population, I arrive at 300 “daily new confirmed COVID-19 deaths”. Turns out SK already bet that, so I’ll go for 299.

The winner… SK! “My assumption it will fizzle our even more. My prediction is 300. Definitely less than 900.”

So… IHME was off by 10X (but maybe only 5X if we smooth the data?). I was off by 2.5X. When is it time to acknowledge that the virus is smarter than we are?

How about the rest of the IHME predictions? Back in April they were predicting 13,259 deaths for Sweden by August 4. The WHO figure from yesterday’s report is 5,744 (i.e., off by 2.5X). The same April post carried a prediction of 6,739 deaths for Massachusetts through August 4. That was without the assumption that the state would adopt universal masking. We did mask up and… the actual number was 8,436 (mass.gov).

In late March, IHME predicted 80,000 deaths for the U.S. through August 4, 2020, with a 95% confidence interval of 40,000 to 160,000. The WHO report number is 154,226. So they were off by almost 2X, but not so far off as to call their methodology into question.

Related:

An update of the big chart from the previous post:

10 thoughts on “How is coronaplague down in Brazil? (and the rest of the IHME predictions)”

  1. As someone who clearly lost and regrets all five minutes I wasted on my forecast, I would actually think that you were closer than SK – deaths have been running just above a thousand – not real down turn yet. That is was so low that day I am assuming someone bribed a postman to delay delivering the results.

  2. The early estimates of coronavirus deaths were not that far off in terms of deaths (aside from Imperial College predicting 2.2 million deaths in the US), but they projected them happening over a much shorter time period than they’re really happening. I think this is largely (although maybe not entirely) because people have drastically changed their behavior in order to try to avoid getting infected (unfortunately we also have cases of people testing positive and going out and infecting others because they refuse to self-quarantine).

    Unfortunately this is not yet over and covid19-projections.com (which I think has been reasonably close over the last few months) is projecting 69,893 additional deaths by November 1 for the US (i.e. an average of about 794 per day). It could be even more than this if many schools reopen, and of course the problem is still going to exist on November 1.

    My friend who’s a chronic optimist claimed that things are going well for Americans because I went to public school and ended up getting a decent job at a large tech company. I pointed out that we basically don’t even have schools anymore at this point.

  3. 2x isn’t bad. The IHME underestimated the stupidity of the American people, both individually, and in their collective decision to elect a moron to govern them.

    • Senorpablo: The 2X error for the US (March to early August) could be accounted for by the fact that in March they believed that Donald Trump was a brilliant scientist and great leader. But what accounts for their 10X error regarding Brazil over a shorter period of time (June to early August)? They underestimated the effectiveness of Jair Bolsonaro and HCQ? If the U.S. 2X overshoot is attributable to Trump’s poor leadership, should we attribute Brazil’s spectacular “control” of the virus compared to the IHME’s prediction to superb leadership by Mr. Bolsonaro (now recovered from his own encounter with Covid-19, thanks to taking hydroxychloroquine on the advice of Dr. Donald J. Trump, MD)?

    • There’s some kind of feedback loop at work in all of this. It’s probably highly variable based on local society and culture. People will adjust how serious they isolate themselves, etc. based on many factors in real time. The shocking ascent of the Brazilian death rate probably got folks to take things seriously. Shots of mass graves in the jungle no the news probably helped. Perhaps the Brazilians removed their hand from the stove once it started to get hot, whereas Americans for Trump attribute it all to fake news–any day now it will drop to zero cases. Here in the US, the shutdown was working perfectly, which lead commoners to believer there never was an issue; it was all overreaction, open it all back up! That too was all predicted by the experts well ahead of time. But, some people can’t learn not to put their hand on the stove from someone with experience, they have to try it for themselves. Global warming is this, but orders of magnitude worse.

  4. It’s better to over estimate and come out wrong with few death than under estimate and come out wrong with many death. Why? You can then say “See, masks, distancing, isolation, shutdown, etc. is helping” and get away with it for saving humanity for extinction.

  5. Is anyone collecting data and plotting them to show the side effect the shutdown (not coronaplague) is having on us? What does the curve looks like? How flat or wide is it and how high does it reach?

    What about the day after? How and when do we know we can put all this behind us and to what extent?

    Is any of this being reported anywhere to be news worthy?

    I guess not and this tells me how short sighted and self destructive we have become but there is hope: https://www.bbc.com/news/world-europe-53622797

  6. You are the man Phil when it comes to corona virus predictions. You should throw your hat in the ring for Anthony Fauci’s job since you seem to have been right a lot more often than he has & he is about 80 and that is high time to hang up the old stethoscope. Note too the editorial in today’s WSJ re Sweden. And the Swedes I know are enjoying their summer in their cabins on the islands off of Stockholm, drinking beer and boating from one island to another while we are masked and locked in doors and a summer passes never to return. But at least we get some satisfaction from ostracizing people in the streets who are unmasked and referring to our President as a “moron” while the the Swedes enjoying their short Nordic summer have no such pleasures.

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