4 ms·
We’ve all seen the time series of diagnosed cases in Italy versus the U.S. in which the latter appears to track closely but with a time delay. Is it relevant th
by gbacon 7y ago
We’ve all seen the time series of diagnosed cases in Italy versus the U.S. in which the latter appears to track closely but with a time delay. Is it relevant that the U.S. population is some 5 to 6 times Italy’s? Is it meaningful to compare populations by cases per capita?
- nbnoll 7y agoIn theory, the exponential growth rate of the virus doesn't depend on the population size. It more strongly depends on the population structure - i.e. the average number of social contacts made in a day.
- dboreham 7y agoWhile there's exponential growth yes, but further up the logistic curve it makes a difference (you can't kill more people than the population of any country).
- nbnoll 7y agoYes I agree. However, I don't think we're close to the inflection point where this is relevant yet.
- spookthesunset 7y agoIt also depends on the growth rate of the number of tests administered. If you exponentially grow the number of tests given (which one could argue is the case in many areas), the absolute number of “confirmed cases” will also look exponential. If you start with a hypothesis that this virus is in wide global circulation already, all this testing is doing is confirming “yup, people have the virus!”. Only way to prove or disprove the hypothesis that the virus is widespread is large scale testing of a truly random subset of the entire population. Last I checked that isn’t happening anywhere in the United States and possibly elsewhere. Why is proving that hypothesis important? Because if true it means the severity of this virus is dramatically less than our limited data suggests. If true, most of the rather draconian measures we are taking are pointless. If false, god help us all I guess...
- Rastonbury 7y agoTheoretically, unbridled transmission will follow a logisitic curve, which is exponential at the start. Test kit production, testing capacity would be linear with spikes when capacity is ordered to be increased or production facilities come online.
- xearl 7y agoThe growth rate of infected deaths and the measurable mortality displacement makes that hypothesis extremely unlikely. As does (albeit in a weaker form) the testing of the full population of Vò. As does the testing in at least a few European countries, where the growth rate of tests outpaces that of confirmed infections. And/or where the number of tests administered vastly exceeds the number of confirmed infections. Sure, once we have anti-body tests widely available, the data will become better.
- TheGallopedHigh 7y agoYou do get finite size effects with non-mean field models.