When constructing confidence interval for a parameter,we generally set the confidence level 1 − α close to 1 (usually between 0.90 and 0.99)because it is the probability that the interval includes the actual value of the population parameter.

Confidence Level

The probability or degree of certainty that a confidence interval would contain the true population parameter if the same procedure were repeated multiple times.

Confidence Interval

A range of values, derived from sample statistics, that is believed to contain the true population parameter with a specified level of confidence.

Population Parameter

A numerical value summarizing the whole population.