A manager of a local store wants to estimate the mean amount spent per shopping visit by customers. Summary statistics from a sample taken reveal the following: If 95% and 98% confidence intervals were developed to estimate the true shopping expenditure, what differences would exist?
A) Standard errors
B) Interval widths
C) t-values
D) Both interval widths and t-values
E) Both standard errors and interval widths

Question

A manager of a local store wants to estimate the mean amount spent per shopping visit by customers. Summary statistics from a sample taken reveal the following:  If 95% and 98% confidence intervals were developed to estimate the true shopping expenditure, what differences would exist?
A) Standard errors 
B) Interval widths 
C) t-values 
D) Both interval widths and t-values 
E) Both standard errors and interval widths

Quizplus · Accepted Answer

The interval widths would differ between the 95% and 98% confidence intervals, as the wider interval is required when a higher level of confidence is desired. Additionally, the t-values used to calculate the intervals would differ, as the level of confidence determines the critical value to be used from the t-distribution. Therefore, both interval widths and t-values would differ between the two confidence intervals. Standard errors would not necessarily differ between the two intervals unless the sample size or population standard deviation changed.

A Manager of a Local Store Wants to Estimate the Mean