April 6: Which "curve" are we talking about?

I am not surprised that folks are confused about the apparent contradiction between "light at the end of the tunnel" and "the worst weeks are still to come", and even Dr. Fauci (with all due respect) did not do a good job explaining that... This goes together with them talking alternatively about "peaks" and about "flattening the curve". The explanation will be totally obvious to folks who have had calculus... but I will assume that that knowledge might be rusty for many at this point. What's been unclear (IMO) is that they have been talking about two different curves, and they have not bothered to explain that fact. The first curve (first picture) shows the daily number of deaths in the US. I have been showing the daily number of new cases. The shape is the same. So, what happens is that deaths (or new cases) keep increasing as the virus takes off. If measures are effective the daily number of new cases (and, later, deaths) will stop increasing. When that happens, we have reached the PEAK of curve one ... The "light at the end of the tunnel"! Assuming that that holds up (and it could stay there, as a "plateau" for a while as Cuomo has mentioned). It's good news because it shows that the virus has been slowed down. But, wait, even if we go to the other side of the curve, deaths keep happening, for a whole month according to figure 1 until, ideally, we have no new cases and, eventually, no new deaths. Let's now look at curve #2. That's for the TOTAL number of deaths! The point where curve #1 reaches the peak is the middle of the rising part of curve #2, so deaths will continue to increase until curve #1 goes to 0. At that point curve #2 has finally been "FLATTENED". So the claim being made is that they "see" the increase of deaths slowing down, at least in some area (so we may getting close to the PEAK), while at the same time we are in the middle of the rising part of curve #2 so deaths will continue .... Oh, well, I tried... For those who remember their calculus, curve one is simply the derivative of curve 2. Real data of course will look much more "messy"!

Comments

Post a Comment

Popular posts from this blog

April 3: How many will die?

Image
It's not clear to me whether the number of deaths predicted by the models shown at the WH briefings (100-240K) refer just to "first wave" (up to the "flattening") or to the entire course of the pandemic. I suspect it's just the former. The reason is that, even without modeling sophistication, unchecked epidemics end up affecting a large % of the population.Harvard epidemiologist Marc Lipsitch, estimates it’s “plausible” that 20 to 60 percent of adults will catch the disease w ithin a year (I have seen more dire estimates). Let's make it 40%, and that's 130M. a 1% death rate would cause 1.3 Million deaths. Social distancing doesn't "kill" the virus, it just prevents it from finding new hosts. Some authorities make it sound like with "flattening" we won the battle. The reality is that it will be the start of a long battle to slowly restart the economy and social "normalcy" while at the same time preventin
Read more

March 16: Reaching the "peak"

Here is a graph of the daily new number of coronavirus cases predicted in Italy. Note that the exponential growth continues for a few more days and finally peaks on March 18 (green is up to now - remember that the rest of the world goes day/month). This is very much like trying to predict where a hurricane will land. The difference (to pursue the analogy) is that what we do actually determines the path and strength of the hurricane! The "problem" with this is that if we m anage to lessen the impact of the virus, all measures taken will be viewed as having been "overreactions", when in fact they were what made the impact less severe. The "peak", if the prediction holds, will happen because of the draconian measures taken a week or so ago. Meanwhile infections and deaths will continue to rise. The expected result is a severely strained medical system. They are now putting beds everywhere they can find space, and basically scrambling to incre
Read more

April 12: A "blue marble" moment

Image
I just finished watching Bocelli's gift perfomance at Milan's Duomo, and I'm still wiping tears off my eyes. This was loaded with emotion for me. My city of birth. A city where most of my beloved relatives still live. A cathedral I have often been in and always inspired by, in appreciation of every person's longing for something "larger" than themselves. And here is a man, blind, unable to see the emptiness of the square in front of him (see the tiny figure in front of the Duomo), but certainly able to feel it. A beaut iful voice, singing on behalf of humanity... to hope and unity. I was suddenly struck by how this felt to me like a new "blue marble" moment, when astronauts on the moon looked up and, for the first time, saw our beautiful Earth, our home, in the sky. If there is a silver lining to this pandemic it may well be a powerful and hopefully lasting reminder of our common humanity.
Read more