The truth sometimes takes longer to explain than a short untruth. Someone posted on Make Votes Matter’s Facebook page, “STV is semi-proportional. If we want a true PR system, only the first choice vote matters, and constituency size is irrelevant. STV delivers F15PTP.”
He managed to pack four inaccuracies into those few words but their brevity makes them easy to understand and could misinform readers.
Although most STV Action readers will know the truth, you may find my reply useful when you discuss voting systems with others. Sorry it’s quite long, but here it is:
“Constituency size is highly relevant. The bigger the constituency, the more proportional the result. The smaller the constituency, the less proportional the result. This applies both to party list systems and STV. It’s basic arithmetic. FPTP with only one representative per constituency is the ultimate in disproportionality.
“You don’t seem to understand STV, especially as advocated in the UK.
“When you refer to “F15PTP”, you may be referring to the practice in Australia, where I understand some constituencies have as many as 15 representatives. Most UK electoral reformers advocate STV constituencies with about 5 representatives.
“However, STV isn’t F15PTP or F5PTP. If it was, the same party would usually win all 15 or 5 seats. Many local elections in England and Wales really are F3PTP and the same party usually wins all the seats even if it has only about a third of the votes in a closely fought 3-way election.
“STV in multi-member constituencies produces a proportional result. The more representatives per constituency, the more proportional the result is, but five per constituency produces quite a proportional result.
“To say STV is only semi-proportional even of parties is simply untrue. In its report published in 2008, the UK’s Ministry of Justice concluded that STV (used for most Northern Ireland elections and all Scottish local elections) was the most proportional system used in the UK – more proportional, for example, than AMS used for the Scottish Parliament and the Welsh Assembly.
“Not only is STV in multi-member constituencies party proportional but it also has many other advantages.
“STV offers non-party proportionality between any other groupings of importance to voters even if they cross party lines; e.g. between Brexit and Remain and between men and women. STV offers more freedom of choice than any other system to voters. STV can avoid wasted votes, whereas most PR systems can only reduce them.
“I recommend http://www./stvact.wordpress.com if you’d like to know more about STV.”