~ problems to procedures.

V An effective vaccine

would reduce the

proportion of exposed

persons contracting a

disease. A pharmaceutical

company wants to test

the effectiveness of a

new vaccine in

preventing a certain

disease. It is expected

that 40% of unvaccinated

exposed people will

contract the disease. A

group of 48 exposed

persons volunteered to

be vaccinated. Later, two

of the volunteers

contracted the disease.

Test HO: rr ~ 0.40

(vaccine ineffective) at

= 0.01. 1. 1-tailed test of proportion with

negative critical value