The plot is function against derivative of function. This is also called a phase...

		fxj on March 29, 2020 \| parent \| context \| favorite \| on: Log-log plot of new vs. total Covid-19 cases by co... The plot is function against derivative of function. This is also called a phase space plot which is quite often used in the dynamic systems theory. https://en.wikipedia.org/wiki/Phase_space

That doesn't answer my question.