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, 11 tweets, 3 min read

If it looks to you like the exponent on infection growth rate is increasing, you are probably right. I just looked at the 5-day LOGEST values (estimate the exponential growth based on last 5 days activity), and the rate has risen 4 out of the last 5 days. Testing just started...

So, this isn't scary to me YET. What it means is not that the real exponential growth rate of infection is increasing, but rather that the rate of our knowledge of exponential rate is increasing. But more testing is still needed to get the numbers to settle down ...

There's gonna be lots of numbers for the epidemiologists and hyper-mathy folks to study RE impact of testing volumes (see ) on estimates of real growth rate when this is over. I don't recall signing up for that clinical trial though.

I suspect there they may even be some new hyper-mathy stuff that addresses statistical process controls applied to exponential growth curves. I kinda faked a control chart with my 5-day moving estimator for the growth rate. There should be some useful signal there ...

I know enough math to know that something should work, maybe even already exists (but maybe and even possibly not yet). I also have enough math to know it's not going to be me who actually proves it.

I've seen enough in that one graph to tell me what I already knew, the real rate is worse than a lot of people thought, or the current graphs show. The good news is that we are seeing a correction now. The bad news may be that it will take a longer time than we want to adjust.

But I'm still not panicking yet.
And neither should you.

I just updated my spreadsheet. The good news is that the infection rate is declining, and has been for eight days in a row. However, it's also stabilized, which means it might be getting ready to inflect the other way.

OK, my chart gets better. I can compute New Cases / Total Cases, which should be a constant for an exponential function. In fact 1/(1-New/Total Cases) recovers the base of it.

Here's the new control chart on the base value, I find it more helpful.

Today's update is promising. The downward trend in growth shows we are making progress. Note that it took two weeks to get farther than 1 standard deviation in the right direction. Maybe by tomorrow we'll be at 2.