Question

Harris Interactive® conducted a poll of American adults in August of 2011 to study the use of online medical information. Of the 1,019 randomly chosen adults, 60% had used the Internet within the past month to obtain medical information.

1. Use the results of this survey to create an approximate 95% confidence interval estimate for the percentage of all American adults who have used the Internet to obtain medical information in the past month.
2. Calculate the 90% confidence interval.
3. Which confidence interval has the smaller margin of error? Why does this make sense?
4. Which confidence interval is more likely to contain the true percentage of all American adults who have used the Internet to obtain medical information in the past month? Why do you think so?

Answer 1

As the level of confidence is low for 90% confidence interval , the margin error is also low for it.

The 95% confidence interval is more likely to contain the true proportion.

here in 95% confidence interval we are more confident than 90% confidence interval and the 95% confidence interval is more wider than the 90% confidence interval. So the 95% interval is more likely to contain the true proportion.