In: Statistics and Probability
A 95% confidence interval for a difference in proportions p1-p2 if the samples have n1=60 with p^1=0.69 and n2=60 with p^2=0.56, and the standard error is SE=0.09.
Solution:
Point estimate of difference between two proportions
= 0.69 - 0.56
= 0.13
Our aim is to construct 95% confidence interval.
= 1.96 * 0.09
= 0.1764
Required interval is
Point estimate
Margin of error
(0.13 - 0.1764 , 0.13 + 0.1764)
(-0.0464, 0.3064)
Required 95% confidence interval is (-0.0464, 0.3064)