“The basics of AV
– A move to the Alternative Vote (AV) would not be a radical change from the current system of First Past the Post (FPTP). AV is not a proportional system.
– Rather, AV is majoritarian: candidates win by securing a majority of the votes in their constituency. Under FPTP, only a relative majority is required; under AV, the goal is that winning candidates should secure an absolute majority.
– AV allows voters to rank candidates in order of preference. If no one wins more than 50 per cent of first preferences, second and sometimes lower preferences are taken into account.
AV’s known effects
– AV would increase voter choice – between but not within political parties.
– AV would reduce but not end tactical voting.
– AV would uphold the principle of “one person, one vote”. Every voter would still be treated equally; each vote would count only once in deciding who is elected in each constituency.
– AV would give weight to second and lower preferences as well as first preferences. The merits of this move can be debated.
– AV is not a proportional system.
– AV would not eliminate safe seats, though it will probably reduce their number.
– AV would not cost much to implement.
AV’s likely effects
– AV would probably not change turnout at elections. Nor is it likely to change significantly the number of spoilt ballots.
– AV is unlikely to change the structure of the party system fundamentally. But it is likely to increase the Lib Dems’ seat share somewhat, at the expense of the other main parties.
– AV would probably make coalition governments slightly more frequent (but changes in how people vote mean coalitions are already becoming more likely under FPTP).
– AV would probably sometimes exaggerate landslides.
– Minor parties under AV would probably win more votes, but not more seats. AV would be likely to increase the bargaining power of some minor parties, but not of extremists such as the BNP. It did not help Australia’s One Nation party.
– AV would be unlikely to increase the number of women or ethnic minority MPs.
– AV would be unlikely significantly to change the standards of MPs’ behaviour or the relationship between MPs and voters. It might make some MPs focus more on constituency work – which might or might not be desirable.
– AV would probably reduce the tribalism of political battle only at the margins.
– A “yes” vote would probably make further electoral system change later on more likely.” (page 2)