In? randomized, double-blind clinical trials of a new? vaccine, children were ra
ID: 3372010 • Letter: I
Question
In? randomized, double-blind clinical trials of a new? vaccine, children 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, 118 of 746 subjects in the experimental group? (group 1) experienced fever as a side effect. After the first? dose, 51 of 623 of the subjects in the control group? (group 2) experienced fever as a side effect. Construct a 99?% confidence interval for the difference between the two population? proportions, p1-p2. Use x1=118?, n1=746?, x2=51?, and n2=623.
The 99?% confidence interval for p1-p2 is ?(____,_____)
?(Use ascending order. Round to three decimal places as? needed.)
Explanation / Answer
The statistical software output for this problem is:
Two sample proportion summary confidence interval:
p1 : proportion of successes for population 1
p2 : proportion of successes for population 2
p1 - p2 : Difference in proportions
99% confidence interval results:
Hence,
99% confidence interval for p1 - p2 is:
(0.032, 0.121)
Difference Count1 Total1 Count2 Total2 Sample Diff. Std. Err. L. Limit U. Limit p1 - p2 118 746 51 623 0.076314985 0.017295595 0.031764484 0.12086549