In a population of 5000 people, 500 are already myopic on January 1, 2011, number of new myopic cases till December 31, 2011 is 9. Calculate incidence:
Incidence = Number of New cases x1000 Total population under risk Incidence = 90/(5000-500)X1000 = 90/4500X1000=2 Ref: Park 22nd ed /p-58.
1.80%
2%
5%
20%