Confidence Interval
The interval estimate or a 'confidence interval' consists of a range as an upper confidence limit and lower confidence limit whether we are confident that a population parameter lies and we assign a probability that this interval includes the true population value
The confidence limits are the outer limits to a confidence interval. Confidence interval is the interval among the confidence limits. The higher the confidence level the greater the confidence interval. For illustration:
A normal distribution has the given characteristic as:
i. Sample mean ± 1.960 σ contains 95 percent of the population
ii. Sample mean ± 2.575 σ contains 99 percent of the population