Question

A research team conducted a critical study, and constructed a 95% confidence interval from their data. The team was not happy with the result because they felt the margin of error was much too large. All other things being equal, if they were to repeat the study, what could they do to reduce the margin of error?

A) They could construct the confidence interval with a lower confidence level than they previouslyused.B) They could include a greater number of subjects in the experiment.C) They could reduce the population standard deviation ?.D) All of the above are possible things for them to try.E) None of the above will work because of the randomness in the experiment.

Answer 1

Explanation:

Confidence interval is written as

Sample mean ± margin of error

Margin of error = z × population standard deviation/sample size

A higher confidence level gives a higher z score. Reducing z and increasing number of samples could reduce the margin of error.

To reduce the margin of error, the correct options are

A) They could construct the confidence interval with a lower confidence level than they previously used.

B) They could include a greater number of subjects in the experiment.