Dummy Variable

A variable that appears in a calculation only as a placeholder and which disappears completely in the final result. For example, in the integral

is a dummy variable since it is "integrated out" in the final answer. Any variable name other than could therefore be used in the above expression, e.g., , , etc.

Dummy variables are also called bound variables or dead variables. Comtet (1974) adopts a notation in which dummy variable appearing as indices in sums are denoted by placing a dot underneath them (i.e., indicating them with an underdot), e.g.,

(Comtet 1974, p. 33).

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