In: Statistics and Probability
In 2001, a Gallup Poll surveyed 1016 households in the U.S. about their pets. Of those surveyed, 599 said they had at least one dog or cat as a pet. Find and interpret the 90% confidence interval (z*=1.645) for the population proportion. Round your answer to 3 decimal places.
Given that,
n = 1016
x = 599
Point estimate = sample proportion = = x / n = 599/1016=0.590
1 - = 1- 0.590 =0.41
At 90% confidence level
= 1 - 90%
= 1 - 0.90 =0.10
/2
= 0.05
Z/2
= Z0.05 = 1.645 ( Using z table )
Margin of error = E Z/2 *(( * (1 - )) / n)
= 1.645 *((0.590*0.41) /1016 )
E = 0.025
A 90% confidence interval for population proportion p is ,
- E < p < + E
0.590- 0.025 < p < 0.590+0.025
0.565< p < 0.615