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