Liberal blogger Scott's DiaTribes posted this excellent analysis on preferential voting (aka 'Alternate Vote' or AV for short.) For those looking for a clear explanation as to why the independent Citizens' Assembly chose Mixed Member Proportional over preferential balloting, you'll find it in Scott's post.
Here's an excerpt:
"I’ve not been as vehement against it as some, so I thought I’d ask one of my fellow bloggers and one of those very involved in the fight for electoral reform, Greg Morrow of DemocraticSPACE.com, what he thought of the preferential ballot/Alternate Vote option that was being bandied about, and he agreed to let me post my “interview” of him on here.
"It turns out Greg is in the camp of those who believe AV would be a worse system to put in place then what we currently have now. His exact quote was that “Preferential ballots are dreadful ways of electing governments.”. He believes that preferential balloting simply formalizes people’s second choices, and that the first choice is basically chosen because they are the lesser of the evils as choices facing the voters, and Greg doesn’t believe that’s a very good way for voters to be electing our representatives.
"He then pointed to the Citizen’s Assembly statement of principles they laid out when they were looking to pick a new electoral system and then said to compare Preferential ballot against that list of principles they put down. His assessment of AV against those principles is as follows:
""Fairness of Representation? Not even close. Voter Choice? No, since you know that one party/person has to get to 50%, it still means you can’t vote for a small party or independent. Effective Parties? Yes, but it tends towards a 2-party system, so its leads to 2 effective parties and a lot of ineffective ones. Effective Government? - it leads to even more distorted majorities, meaning opposition is ineffective. Does it encourage more women and minorities? On the contrary, it makes it worse."
"Greg made the point that the CA members obviously felt the same way about AV, because when the 103 members came to vote on what electoral system to endorse, only 2.1% of them supported the AV model."