[EM] voter strategy & 2-party domination under IRV voting

[James Gilmour]

Scott Ritchie Sent: Friday, August 19, 2005 10:21 PM
> I believe the Maltese movement towards two parties is an 
> artefact of the Maltese version of STV.

Not so. The 'bonus seats' provision was added to the electoral law only in 1987, but only two parties have won seats in
the elections since 1966, ie long before the provision was introduced.

> Due to the Maltese 
> systems method of granting bonus seats based on the 
> top-choice ranking of candidates,

The 'bonus seats' are added according to complex rules based on the national totals of first preference votes.  This is,
of course, completely illogical because in STV-PR it is the final votes, after all transfers, that best reflect the
voters' wishes, and it takes no account of the effects of differential turn-out across the electoral districts.  NB The
'bonus seats' are allocated only when the normal STV tabulation has 'failed' to give an overall majority of seats to the
'right' party.  (This can be a 'problem' with any district-based voting system.)

> the Maltese system is 
> really a lot more like an open list PR system with the 
> voter's indicated first preference acting as their party tick.

The Maltese system does function in some ways like the very best of the open-list party-list systems, but not for the
reason Scott suggested.  Rather it is like open-list because the voters do not mark preferences across the parties.
Nothing in the system imposes any penalty for marking such cross-party preferences.  The preferences observed simply
reflect the extremely partisan nature of Maltese politics.

> This strange rule leads to a partisan strategy of trying to 
> win more first tick votes on a party basis in an attempt to 
> hedge bets on the bonus seats, granting a significant bonus 
> to partisan grouping not present in typical STV systems.  
> This is important, as in Malta it is not nearly as profitable 
> to run as an independent or minor party candidate as you then 
> lose your chance of getting into the government anyway on a 
> bonus seat, which requires being a loyal party member to do
> - leading to a strong force against third parties.

As the 'bonus seats' are allocated only on first preference votes, this feature does not create a disincentive to giving
later preferences to candidates of smaller parties or to independents.
 
> By the way, check out the section on Malta at the newly 
> featured article on STV at Wikipedia: 
> http://en.wikipedia.org/wiki/Single_Transferable_Vote 

You need to look for more detailed info than you will find there if you really want to understand what has happened in
Malta.

> Note that Ireland has significantly smaller districts than 
> Malta - somewhere between 3 and 5 candidates in Ireland, and 
> frequently much more in Malta.

The STV districts in Malta all return 5 members.  In Ireland the average is now 3.95 members per district, comprising 16
x 3-member, 12 x 4-member and 14 x 5-member.  (The average was 4.62 in Ireland when STV was introduced in 1920, but the
6, 7 and 8-member districts were all split later.)

> Yet, Ireland has less 
> reliance on parties, despite being less able to represent 
> smaller parties due to the smaller voting districts.

I would not say Ireland "has less reliance on parties" (despite the presence of 13 independents among its 166 TDs), but
its voters are certainly much less partisan and cross-party voting is normal.  The degree of party proportionality
achieved in Ireland is indeed remarkable, given the appalling and unnecessarily low average numbers of TDs elected per
district.  It is a travesty of an implementation of STV that has 3 and 4-member districts in the densely populated
cities where there should be 7 and 8-member districts.
Regards
James Gilmour