The article proposes a theoretical framework for understanding financial ratios, showing that the multiplicative character of the financial variables from which financial ratios are constructed is a necessary condition of valid ratio usage, not just an assumption supported by evidence. Also, by...

This note discusses metrics that have been used frequently during the coronavirus pandemic: (i) the growth in the number of cases and deaths; (ii) the time they take to double; (iii) the re-infection ratio, generally known as the reproduction ratio R; and (iv) the excess mortality above the norm....