Question

In​ randomized, double-blind clinical trials of a new​ vaccine, subjects were randomly divided into two groups. Subjects in group 1 received the new vaccine while subjects in group 2 received a control vaccine. After the first​ dose, 107 of 724 subjects in the experimental group​ (group 1) experienced fever as a side effect. After the first​ dose, 60 of 641 of the subjects in the control group​ (group 2) experienced fever as a side effect. Construct a 95​% confidence interval for the difference between the two population​ proportions, p 1 minus p 2.

Answer 1

Sample 1:  
n1 =   724, x1 =    107
p̂1 =   0.1478
Sample 2:  
n2 =   641, x2 =   60
p̂2 =   0.0936

At α = 0.05, two tailed critical value, z_c = NORM.S.INV(0.05/ 2) = 1.960

95​% confidence interval for the difference between the two population​ proportions