At Westonci.ca, we connect you with experts who provide detailed answers to your most pressing questions. Start exploring now! Our Q&A platform provides quick and trustworthy answers to your questions from experienced professionals in different areas of expertise. Join our platform to connect with experts ready to provide precise answers to your questions in different areas.

Margin of Error. Find the margin of error and the 95% confidence interval for the following studies. Briefly interpret the 95% confidence interval.According to Gallup a poll of 1012 people, 32% (about one-third) of Americans keep adog for protection.

Sagot :

The formula for determining margin of error for a population proportion is expressed as

[tex]\text{Margin of error = z}_{\frac{\varphi}{2}}\sqrt[]{\frac{p^{\prime}q^{\prime}}{n}}[/tex]

where

p' is the estimated proportion of success. It is also the point estimate

q' is the estimated proportion of failure

n is the number of people sampled

z alpha is the z score corresponding to a 95% confidence level

From the information given,

The success in this case is the proportion of Americans that keep a dog for protection. Thus,

p' = 32/100 = 0.32

q' = 1 - p' = 1 - 0.32 = 0.68

n = 1012

z alpha for a 95% confidence level is 1.96

Thus,

[tex]\text{margin of error = 1.96 x }\sqrt[]{\frac{0.32\times0.68}{1012}}\text{ }[/tex]

Margin of error = 0.015

The confidence interval is written as

margin of error ± margin of error

Thus, the 95 confidence interval is

0.32 ± 0.015

The lower limit is 0.32 - 0.015 = 0.305 = 0.305 x 100 = 30.5%

The upper limit is 0.32 + 0.015 = 0.335 x 100 = 33.5%

The interpretation would be

We estimate with 95% confidence that between 30.5% and 33.5% of Americans keep a dog for protection.