The width of a confidence interval equals twice the sampling error.

Question

Quizplus · Accepted Answer

This statement is true. The formula for the confidence interval is: 
point estimate ± (critical value) x (standard error). 
The critical value and standard error are both related to the sampling error. If we assume a normal distribution, the critical value is determined by the level of confidence and sample size. The standard error is the standard deviation of the sampling distribution, which is related to the population standard deviation and sample size. Therefore, the width of the confidence interval (which is the distance between the upper and lower bounds) is proportional to the sampling error, and specifically, it is twice the sampling error when the level of confidence is 95%.

The Width of a Confidence Interval Equals Twice the Sampling