Scale invariance

Scale invariance can refer to one of two criteria: a cardinal voting method criterion and an ordinal one, and these can be multiplicative or additive.

The cardinal method criterion (multiplicative version):

The additive version:

with a stronger variant being (multiplicative):

Additive:

The ordinal method criterion is also called the homogeneity criterion. It is (multiplicative):

Additive:

These criteria represent a desideratum that the method should not rely on absolute numbers when selecting a winner, just on the candidates' or factions' relative support.