How can the size of the confidence interval containing the mean be made smaller?
A) Use a 99% percent confidence level rather than a 95% percent.
B) Increase the value of the standard error.
C) Decrease the sample size.
D) Decrease the variance by redefining the population to a narrower population.

Question

Quizplus · Accepted Answer

Decreasing the variance by redefining the population to a narrower population directly reduces the variability in the data, which in turn reduces the width of the confidence interval. A smaller variance means the data points are closer together, leading to a more precise estimate of the mean, hence a smaller confidence interval.

How Can the Size of the Confidence Interval Containing the Mean