[E-voting] need help finding a reference

Michael McMahon Michael.McMahon at Sun.COM
Thu Feb 11 10:17:57 GMT 2010

Colin Whittaker wrote:
> I ended up in a debate yesterday with some colleagues about the impact
> of plumping or bullet voting - this is voting for only a single
> candidate in a multi seat election.
> They were contending that this is bad and has an undue impact on the
> result and voters should be required to express as many preferences as
> there are seats or the vote will count as spoiled.
> I "know" this is wrong but I need to find a nice reference that I can
> point to that explains this. Anyone got any suggestions,
> google/wikipedia not helping so far.
> This is not a completely abstract debate as we intend to run a prstv
> election next month to fill a bunch of committee positions and it turns
> out this is the first time we have had more candidates than there were
> seats.
> Colin
Generally, it's not in a voter's best interest to only vote for one 
because if their candidate is eliminated, then they have no further
influence on the outcome. If their candidate is elected, then while
they have helped to elect them, they also have no further influence
on the outcome of further seats.

But, I think it might be a bit strong to say that voters should be required
to express all preferences, or as many preferences as seats.

First, because someone might genuinely have only a first preference
and really doesn't care about the others. In that situation, it's reasonable
in my opinion, to only express one preference.

Second, it's hard to know exactly how many preferences are actually counted.
It depends on the contents of the votes themselves, and obviously varies 
one ballot paper to another. But, from my limited observations, it would 
be typically
less than the number of seats.

- Michael

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