-Because the growth rate is exponential, it's best to take logs of the data
-I prefer data on active cases rather than total confirmed cases. This is because people who have recovered or died aren't spreading the disease anymore. Unfortunately, I haven't found good data on recoveries. That is why I look at the total number of confirmed cases.
-I run statistical tests to find significant changes in the trend
-The curve was flattening for a while until late June
The tests found 7 distinct periods. The first period was the beginning until March 22. Growth was very rapid back then. You can see that in the table below; the coefficients are circled. The number next to "t1" is the slope in the first period. The slope drops from 0.14 to 0.12 for the second period (March 23-April 13). It keeps falling but then it begins to rise in period 5, which began on June 17. It rises again on June 27. But now we are in period 7. It started on July 18 and the slope began to decline again. The number of cases is still going up, but at a slower rate now.
I graphed the data along with the trend lines, but it is hard to see all of them in the top graph. In the bottom graph, I only show the trends.
Stay safe!
