What is this magic? > Effectively, this allows us to look at the past 12-16 months (each country is slightly different) before vaccine administration began, th

What is this magic? > Effectively, this allows us to look at the past 12-16 months (each country is slightly different) before vaccine administration began, this is called the pre-intervention period, and utilize that data to project where y1 (total deaths per million) and y2 (total cases per million) would have been had the intervention of X (vaccine administration) not occurred If authors can predict future values based on past time series, why they are not making millions on a stock market?