The probability of covering the expected value of an estimated parameter with an interval estimated for the parameter (symbol 1- α). The confidence level can be expressed as a number between 0 and 1, or in percent. The complementary quantity is known as the significance level.
Note:
In some cases the confidence level is dictated by the needs of the situation. In all other instances, use of 1- α = 0.95 is recommended.
Source:
PAC, 1994, 66, 595. 'Nomenclature for the presentation of results of chemical analysis (IUPAC Recommendations 1994)' on page 599 (https://doi.org/10.1351/pac199466030595)