How so? They said they computed the second derivative. What more is there to say?
You can’t compute the second derivative of data from May 2020 when it is currently March 2020. Where did the data come from?
China data time shifted to match the country of interest.
That seems to make a pretty big assumption western countries can achieve that? My understanding even a small amount of non compliance has big consequences...
FTA: The cumulative deaths for each country, N(t), were estimated by deriving a multiplier Nfinal/N(tconv) at the time of convergence, tconv, to the Chinese trajectory, Nfinal being the total number of deaths in China and applying this multiplier to Chinese data for times beyond convergence.