Question

The focus this week is on confidence intervals. Utilize the following information and answer the questions below: A 95% confidence interval obtained from a sample of 100 outpatients for the true population mean normal mean systolic blood pressure is given by (114 mmHG, 120 mmHG).

• Provide a correct interpretation of this interval. Can you think of other interpretations that would also be correct?
• This confidence interval came from a single sample, would we get the same interval if we obtained a different set of 100 patients? What does this imply about your interpretation of the given interval?
• If we wanted a 99% confidence interval instead, can you tell whether it would be narrower or wider? Can you tell by how much?

Answer 1

Interpretation 1: We're 95% confident that the true systolic blood pressure mean lies in the above-mentioned interval.

Interpretation 2: If repeated samples were taken and the 95% confidence interval was computed for each sample, 95% of the intervals would contain the population mean.
No, we won't get the same confidence interval, though there is a 95% chance this interval contains the true mean. Thus we can say that although the intervals may not be the same we're 95% confident for both samples to contain the true mean.

The 99% confidence interval would be wider. The margin of error will be changed. The critical value is changed due to the confidence level. the ratio of the increase will be given by =1.314