A drug has been developed that may reduce a person\'s cholesterol. Investigators

Question

A drug has been developed that may reduce a person's cholesterol. Investigators are interested in estimating the amount by which the drug will reduce cholesterol, and in calculating a confidence interval. For each of the following, say whether the change will cause the confidence interval to get wider or get narrower: (a) The investigators decide to enroll more people in the study (b) More sophisticated lab techniques are used, allowing for more accurate measurement of cholesterol (c) The investigators want a 99% confidence interval instead of a 95% confidence interval Which statistical procedure tells you more about the clinical significance of a study? (i) confidence intervals (ii) hypothesis tests

Explanation / Answer

(a) As sample size increases, confidence interval will get narrower because margin of error decreases.

(b) More sophisticated techniques give lower standard deviation, that decreases the margin of error. Therefore, confidence interval will get narrower.

(c) The 99% confidence interval would be wider (larger margin of error) than the 95% confidence interval, because it allows one to be more confident that the unknown population parameter is contained within the interval.

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