graeme edgeler at public address has an excellent Q&A on STV. One or two blogs that purport to be specialist local body blogs have shown a dismal lack of knowledge on how STV works. They should also link to Graeme's analysis. Some extracts:
But is it a good idea to rank everyone?
But if i give someone I don't like a rank, couldn't this hurt the chances of candidates I like more?
Your lower preferences cannot ever harm the election prospects of anyone you rank higher than them.
This is key. Don't try and be strategic and working out who is most popular and hence I will rank them lower as they don't need my vote etc. Just rank candidates in order of your true actual preference.
But what if I really don't want to rank everyone?
You don't have to. If there are a bunch of people whom you think are just as bad each other, or you know nothing about, your vote will still count. If the election comes down to race between people you haven't ranked, you won't help determine the result, but if you don't mind which of them is elected, this shouldn't bother you too much.
But if there's someone I really really don't want elected, I should rank everyone else above them
This is again on the mark. If you have no opinions on a group of candidates you can leave them unranked. However if there is a candidate you definitely do not want to be elected, then you should rank all candidates and rank them bottom.
An informed vote is always a good idea.
Even for the District Health Board?
Okay, you got me. Health Board elections are stupid.
Yes they are. Please National get rid of them.