prev next front |1 |2 |3 |4 |5 |6 |7 |8 |9 |10 |11 |12 |13 |14 |15 |16 |17 |18 |19 |20 |review


If you categorize the populations by age and compare mortality of Area A with that of Area B,
area A
area B
age<60
dead/population
500/10,000
250/5,000
mortality
5%
5%
60=<age
dead/population
0/0
750/5,000
mortality
-
15%


If you categorize the population according to the age, population A and B has same risks under the age of 60 years old.

There are no people over 60 years old in area A.

The difference of mortality in previous slide is due to difference of age distribution of the population.