How do I interpret a confidence interval?
Answer
When interpreting a confidence interval, say that “We are __% confident that the population parameter (mean, proportion, etc.) falls between __ and __. It may seem more intuitive to say that there is a 95% probability that the interval contains the true parameter, but this is incorrect. The confidence level doesn’t describe the probability of one interval containing the parameter; instead it’s a statement about the overall percentage of intervals containing the parameter if we found intervals for a large number of samples.