This post is written April 1 2020 but it is most decidedly and unfortunately NOT a joke. I feature the data prominently because in an exponentially growing pandemic, these numbers will be difficult to interpret without being able to note "Oh yeah, that was like 4 days ago" or whatever.
From the data on https://en.wikipedia.org/
wiki/2020_coronavirus_ pandemic_in_California I tabulated cumulative cases and cumulative deaths from the cited article. I calculated daily new cases and deaths by taking differences. Plotted it all on logarithmic axes.
By counting dots on cumulative cases, determined it is taking 12 days to rise tenfold. That is 21% rise per day. That is doubling time of 3.6 days. Counted over two decades of rise a.k.a. 6.6 doubling times.
Here is same plot, with a straight line (on semilog plot) of the 12 day doubling time superimposed on each line.
All four lines seem essentially consistent with a slightly noisy exponential.
What does it mean? California locked down in mid-March, the statewide stay-at-home order was 3/18/2020. I plotted this data to look for what effect this might have had on the data. Using my old eyes, I see nothing.
What does this portend? If this trend continues another week (through April 6), California will have nearly 27,000 cases and have accumulated nearly 5,000 deaths. If it continues throughout April, at the end of April nearly 7% of Californians will have been infected and more than 1% of Californians will have died from Corona.