Data analysis of COVID 19 stats New York vs USA

Let's look at the COVID19 testing data (taken from https://covidtracking.com/). I took the daily difference of the total, which represents the number of new cases identified per day. This can be seen plotted on a log-linear plot, where exponential growth becomes a straight line.

First, the good news. The US testing has been ramping up at an impressive rate. It seems to be following exponential growth, with the type of scale-up that is unprecedented in most conventional hardware manufacturing. In just the last 2 weeks we've gone from 2,300 tests per day to 85,000.

Now the bad news. It is clear that in the past weeks, the virus has followed an exponential growth trend with frightening consistency, as daily positive tests climbs with a doubling time of ln(2)/0.3= 2.3 days. We can assume that the worst is yet to come, since there is no clear sign of the growth slowing. If this continues, in one week we will have 100,000 new positive cases per day. We can also see that the national average positive test rate is nearly constant, at around 15%.

If we perform this same analysis with New York we can some interesting differences as compared to the national average.

First, testing does not seem to fit the same growth pattern as the national average. For some reason, the number of tests seems to be stalled at around 12,000 per day, despite the fact that New York has around half the total US cases, and total US test capacity is closer to 85,000 per day. So in terms of getting enough tests, it seems like New York is getting screwed on a per capita basis.

The next thing to notice is that the distance between the two curves (equal to their ratio on a log-lin plot) is smaller than the national average. That's because the positive rate in New York is closer to 40% than the national average of 15%. That means that nearly half of people that get a COVID19 test in New York are testing positive. I am not totally sure about the implications of that, but it almost certainly means not nearly enough testing to have any chance of containment. The silver lining is that the number of new positive cases per day seems to be leveling off in New York. However, with the stories coming in of an overwhelmed healthcare system, I wonder if it's because the virus is slowing down, or if testing is falling behind...