[EM] To Bill Lewis Clark re: stepping-stone

[Dgamble997 at aol.com]

Various people have said that IRV has no real advantage over Plurality.

Consider a three party system like England ( or a four party system like 
Wales or Scotland). The third party In England the Liberal Democrats is 
consistently underrepresented in the House of Commons. In their book (The British 
General Election of 1997) analysing the 1997 General Election the authors make 
calculations of the number of seats the parties would have obtained under the 
Alternative Vote (IRV). The Lib Dems actually obtained 46 seats out of 659, under 
IRV they would have obtained 91. 

Whilst IRV is certainly inferior to any proportional system ( such as STV or 
MMP) in probably all British General elections since 1960 the third party 
would have gained more seats under IRV.

For an example of how unfair single seats elections under Plurality consider 
the 1983 General election result.

Conservative  42.4% vote 397 seats
SDP/Liberal Alliance  25.4% vote 23 seats
Labour  27.6% vote 209 seats
Others 4.6% vote 26 seats

Any single seat system will give similar distorted representation but the IRV 
result would have been less distorted. This is because the Alliance candidate 
being the centre candidate would have gained the second preference support of 
most Labour and most Conservative voters and therefore could have won any 
seat where they gained second place and where the 1st place candidate lacked a 
majority.

David Gamble

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20040124/46b21e82/attachment-0003.htm>