The comparison of moality rates between two countries requires the application of direct standardization. Which if the following parameters makes it necessary to have standardization?

Moality rates between two countries are not comparable because these populations have different Age compositions. The difference in age between two sets of population (two countries) does not allow the moality rates of the two populations to be compared. Direct standardization is used to remove the difference in age distribution thus allowing the comparison of moality rates. Ref: Park's Textbook of Preventive and Social Medicine 19th Edition; Pages 54 - 55.