degrees of freedom, Math - title
A statistical quantity indicating the number of values which could be arbitrarily assigned within the specification of a system of observations. For simple replication, with Math - text measurements and one estimated parameter (the mean), Math - ei. More generally, for multivariable computations, the number of degrees of freedom equals the number of observations minus the number of fitted parameters.
Source:
PAC, 1994, 66, 595 (Nomenclature for the presentation of results of chemical analysis (IUPAC Recommendations 1994)) on page 599