First past the post elections result in vote dilution

Vote dilution is the phenomenon of larger parties being disproportionately represented (in the legislature) in the outcome of first-past-the-post elections.

Dilution: (noun) The action of making something weaker in force, content, or value.

Vote dilution is evident in the outcome of the 2010 United Kingdom general election. The Liberal Democrats achieved 6,836,248 votes compared to 10,703,654 for the Conservative party and 8,606,517 for Labour. This resulted in 57 seats (for the Lib Dems), 306 seats and 258 seats respectively. Accordingly the Liberal Democrat vote dilution factor is 3.5 which is (6,836,248)/(10,703,654 + 8,606,517) divided by (57)/(306 + 258).

The equivalent vote dilution figure for the Greens (who achieved one seat in the Brighton Pavilion constituency) is 7.7.