Here's how I look for Covid-19 spikes, outbreaks, and blowups

[Bernardo de La Paz]

I compare daily new cases (detected) and divide that by the number of active cases (detected), using data from https://www.worldometers.info/coronavirus/ though other sites data can be used too.

1) Only active case cases can infect.
2) Detected cases / deaths are proxies for actual cases / deaths (some unknown multiplier).

This will find second waves in places that have a lot of recovered & dead cases.

On worldometers Yesterday button (for a complete days worth of data) I can sort the Active Cases column and then run down the New cases column looking for states/countries where the new cases is higher than nearby ones in the list. Then I can do the division on a few prominent states/countries found that way.

The US as a whole is running about 2% by that ratio, which is rather good and an indication that the PEOPLE are taking big precautions -- no help from the federal government.

When it gets to about 5%, that is a bit alarming. Texas has been running about 5%, and going by yesterday's figures, Louisiana is about 5%. Tennessee about 7%.

10% is a genuine outbreak. North Carolina, Mississippi, Wisconsin are about 9-10%. Minnesota is high, has been over 10% for a while.

Brazil is running about 15% and is blowing up on its first wave. Mexico is over 20%.

Ideally the data is smoothed by 3 day or 7 day running averages because there are jumps and dips that are from effects like weekend vs weekday.

Daily New Cases divided by Active Cases, as a percentage.

[OnlinePoker]

1. But Brazil and Mexico are hot countries

They shouldn't have very few cases according to Trumplestilskin.

[Igel]

10. The claim is "worse" transmission in warm climates.

That means the prediction is that Mexico and Brazil will have lower transmission because of the temperature than they would if it were colder.

Given just that, the claim's not falsifiable. The only way to partially validate it is by comparison with colder climates (which lacks a control--all kinds of things change at once) or by setting up an experiment to see if you can get higher transmission rates by cooling the climate (which lacks ethics).

I guess if you compared rates for similar towns high up in the mountains (where it should be cooler) and down closer to sea level it could work. Or perhaps inland versus on the shore (with that nice onshore breeze during the day). Humidity wouldn't be controlled for, however.

[BComplex]

2. North Carolina has a huge outbreak of RED NECKS!

They're running around not wearing masks, and talking about how awesome trump is, and how the inflated numbers are the democrats' way of trying to destroy his presidency.

If it was only them who were getting sick, I would be fine with that. But my husband works retail for an essential service, so he's out there every day serving these dick heads.

[samplegirl]

4. Sounds like the people in Ohio

[Bernardo de La Paz]

7. "If it was only them" is such an unfortunate state of affairs. Few will feel remorse. . . . nt

[CanonRay]

12. We've turned into a nation of morons

Every place is full of them.

[Buckeye_Democrat]

3. Seems logical to look at the percentage growth.

And even if they're sometimes "isolated cases" like at a prison or a meat-packing plant, they're still outbreaks for that state or country.

[Bernardo de La Paz]

9. Yes, but the insight (I think) is to compare Active case, not Total cases

Everyone, including the media is focused on the total number of cases. But many of those are recovered or dead. They won't be infecting people any more.

So a place like India has only about 6,500 new cases a day these days and if you compare that to total cases about 125,000, it looks not too bad, about 4% daily. But active cases are about 69,000, so the New to Active ratio is over 9%.

Three countries have about the same number of daily New cases yesterday: Argentina +718, Germany +692, and Italy +652. Which ones are doing better?

If you look at the Total cases, they are respectively 10,700, 180,000, and 229,000. So Germany is still comparable to Italy.

But look at Active cases, respectively 7,000, 12,000, and 59,000. If you divide the daily New by the Actives you get these percentages: Argentina 7%, Germany 6%, and Italy 1%.

So you can see that Italy really has a handle on the spread, Germany and Argentina not so much. Germany is farther along the curve and may be declining as a percent, where Argentina is in an earlier phase of the curve and may be rising as a percent. (Brazil is 15% and Mexico is over 20%).

[Buckeye_Democrat]

17. Yes, very good points!

Your method is definitely the more logical way to estimate the spread of infection.

[Bernardo de La Paz]

18. The Germany figure may be an anomaly: the next day (now yesterday) it is only 273 new cases

273 / 11720 = 2.3 %, much better.

This is an example of why data smoothing is needed.

[Karadeniz]

5. Thanks, that was so interesting...keep us posted!❤

[BigmanPigman]

6. Wow, you are a mathematical dynamo!

I just look at all of those Worldometer numbers everyday too but I do not get anywhere near your use of the info. Thanks!

I have noticed that the Middle East and S America are increasing a lot more than other areas.

[progree]

8. Big tip: click the Yesterday button (as you mention)

just above each table on the left side.

I had missed that or forgotten that, but is important because for today's new cases, (and new deaths and new anything), it depends on the time of day and different jurisdictions report at different times.

[blitzen]

11. What if you bracket out New York? The U.S. is probably higher than 2%...

New York has had by far the largest number of cases, but also they have done a much better job in decreasing the curve. In other words, it is thanks to New York that the U.S. seems to be doing okay.

[Bernardo de La Paz]

14. That would boost US ratio fr 2.2% to 2.7%. Not great but not as bad as some states / countries

US has 1,114,000 active cases, NY 276,000.
Yesterday US had 24,200 new cases, NY had 1,600.

So US ratio is 2.2%, NY is 0.6%.

Take out NY: US would have only 838,000 active cases and 24,200 - 1,600 = 22600 new cases. 22600 / 838,000 = 2.7%

[blitzen]

15. Thanks--good info! n/t

[uponit7771]

13. Is the US 2% sans NY? NY Metro skews the numbers heavy. Quomo showed the graph this morning & it was

... scary

[Bernardo de La Paz]

16. NY ratio is only 0.6%. It has few new cases compared to a massive number of active cases. . . . nt