American Jerk behind COVID surge : Derivatives of displacementCleaner Chart:
The recent increase in acceleration (known as "jerk") of US COVID cases is "re-bending the curve". In this context the verbal descriptions of change, and its derivatives ,becomes both interesting and important Charts showing ongoing change in confirmed US COVID19 cases are themselves constantly changing. Understanding these 'charts of change' is a prerequisite for making informed public policy decisions, as well as individual decision making (to mask or not to mask?). Yet verbal explanations of change are outpacing graphical representations in mainstream media. This is the position taken in the NYT article "Bending the curve". To quote the author:
As an old Chinese philosopher never said, “Words about graphs are worth a thousand pictures.”
The public at large understands the concept of displacement: change over time. For example, is the number of new cases per day going up or down? However, the derivatives of displacement are not commonly understood. You may get a blank stare in response to questions like:
1) The US flattened the curve in the spring of 2020. Did that mean fewer new cases per day?
2) "A jerk is responsible for recent spikes in new cases" Is that:
a) a description of change?
b) a political statement?
Methodology:
The chart is a brief overview of the first 4 derivatives of displacement [Left panel and there application to recent (10/25/2020) data on he number of confirmedrUS COVID19 cases.
Raw data was TV's ticker "COVID19:CONFIRMED_US" Each derivative was calculated on a 7-day SMA of the previous step. Both 5MA and 7MA are commonly used in summary graphs published by John Hopkins (2). Deritives are shown for Acceleration and Jerk. A BB% score shows that both Acceleration and Jerk are 2STD above their mean. It is statistically likely that ,as the Jerk becomes more prominent we may experience an upward "Snap" in US COVID cases. While its easy to visualize an acceleration or even a jerk in virus spread (both have exponential growth), it is much harder, and is left as an exercise for the reader, to visualize "snap" spread of a disease.
Another conclusion is that any attempt to "re-flatten the curve" will fail in the presence of persistent jerk.
(1) www.nytimes.com
(2) coronavirus.jhu.edu
