4 ms·
This is accounted for in more professional methods which estimate error. During a period of exponential growth, the error 6 weeks out is very sensitive to tiny
by tel 6y ago
This is accounted for in more professional methods which estimate error. During a period of exponential growth, the error 6 weeks out is very sensitive to tiny errors occurring in immediate measurement.
It's not so much that fitting exponential or S-curves is hard as much as even a very good fit is likely to have very significant error bars.
The hard parts about modeling the current situation involve the poor and limited data. The dynamics of the system are highly variable and unobserved and thus require clever tricks to reduce uncertainty by expert knowledge, clever alternative signals, and leveraging other models.
So ultimately, it's just not the forecasting but the response. People rarely handle uncertainty very well and a situation with uncertain exponential growth ends up with exponential uncertainty. Making policy decisions where the predicted outcome spans orders of magnitude is tremendously challenging.
- acqq 6y agoExactly. And I have a very recent example, yesterday somebody responded to one of my replies with: "Cuomo claimed to need 40k ventilators after the lockdown was put in place. He ended up needing only a fraction of that. Obviously, without the lockdown, there would likely be more needed. Of course, modeling has errors, but this is an extremely large error, and one that has direct policy implications." (1) My response was that it wasn't "a large error" but what only 6 more days of exponential growth would have made still insufficient: https://news.ycombinator.com/item?id=22911465 https://news.ycombinator.com/item?id=22911465 Also as an illustration of the "uncertainty" one can see the shaded areas clearly here: https://covid19.healthdata.org/united-states-of-america https://covid19.healthdata.org/united-states-of-america As I write this, the model on that page was last time updated based on the data up to the 15th of April, only 4 days ago, and its best estimate for number of deaths in USA on 19th of April was 37,056. Also as I check the https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/ it's already 40,423. But the 95% error area for 19th is 39,721-56,108. It's that hard. Also at this moment the projection for 1st of June is 60,262 (34,063-140,106) and we can compare all these values after some later updates, e.g. in 6 and 12 days. 1) careful observers know that there is one more talked about person who is used the same pseudo-argument before.
- acqq 6y agoRechecked the page: currently data up to 20th April, 22th of April page updated: June 01, 2020 projection: 67,444 (48,058-122,203) Today's number of deaths in the U.S., according to worldometers: 47,808. Today is April 23.
- acqq 6y agoNext recheck: currently death data up to 25th April. June 01, 2020 projection: 73,621 (56,562-128,167) Total number of deaths in the U.S., worldometers: 56,803. Today is April 28.
- acqq 6y agoNext: currently last death non-projected data: May 01: 65,249. June 01, 2020 projection: 112,073 (91,586-155,417) Total number of deaths in the U.S., worldometers: 74,114. Today is May 06.