Question

What is the confidence interval estimate? Provide two examples.

Answer 1

Statisticians use a confidence interval to describe the amount of uncertainty associated with a sample estimate of a population parameter.

The confidence level describes the uncertainty associated with a sampling method. Suppose we used the same sampling method to select different samples and to compute a different interval estimate for each sample. Some interval estimates would include the true population parameter and some would not. A 90% confidence level means that we would expect 90% of the interval estimates to include the population parameter; a 95% confidence level means that 95% of the intervals would include the parameter; and so on.