A positive integer normally equal to the number of independent observations in a sample minus the number of population parameters to be estimated from the sample. When the chi‐squared test is applied to a contingency table with h rows and k columns, the number of degrees of freedom equals (h−1)(k−1).

For a number of distributions, the number of degrees of freedom is required to identify which of a family of distributions is to be used. The chi‐squared distribution and t‐distribution each have a single degrees of freedom parameter, and the F‐distribution has two such parameters.