scd88 said:
Can someone help me understand the cumulative daily rate?
Think of it like an APR of compound interest.
Let's say in year 1 you invest $1,000. You leave it alone and it earns interest at some rate. On year 21 (so 20 years have passed), you look and you have $2,653. What was your APR assuming simple interest compounded once per year? It was 5%. There's a formula to backsolve for that 5%, but you can check by taking $1,000 times 1.05 (and then keep multiplying by 1.05 19 more times). Or, you can take 1.05 to the power of 20, and then multiply by $1,000.
The numbers I posted are the same thing, but a DPR (daily periodic rate) rather than an APR needed to get from our first day of cases (4) to wherever we are on each day since.
On April 30, the day before Texas started reopening, we had a total of 197 cases. It took a daily rate of 9.72% each and every day to get us from those first 4 cases to those 197 cases.
Today we have 2,704 cases. It took a daily rate of 6.05% each and every day to get us from the first 4 cases to those 2,704 cases.
Why is it important to look at this? To know if things are getting better or worse. The absolute numbers will always grow and will always make it look like things are getting worse. And, absolute numbers do matter in terms of hospital beds (which by the way we are just fine on as of right now despite the constant "in two weeks there will be doom, I tell you, doom!" predictions). But, if we look at the rate like this, we can see that we absolutely are flattening the curve -- this is literally the definition of flattening the curve. The rate at which the number of local cases is growing is steadily decreasing, even after reopening and even after holiday weekends and protests.
We won't really know if the mask edict is making a difference for at least another week given the long incubation period of COVID-19. If the rate keeps decreasing at about the same rate it was already decreasing, then it means that masks didn't really improve anything -- it was already declining. If the rate decreases at a faster rate though, then we can guess that masks are making an impact.