variable, x

The quantity or characteristic measured or computed. The corresponding numerical value may be taken for statistical handling; it may, for example, be a measured value or result.

Comment:

Note that statistical usage employs capital letters for random variables, and lower case for particular or observed values. In circumstances where the choice of ' $x$ ' as the symbol may cause confusion, another symbol may be used.

See also: dependent and independent variables

Source:

PAC, 1994, 66, 595 (Nomenclature for the presentation of results of chemical analysis (IUPAC Recommendations 1994)) on page 597