The concept of the second choice of party vote should work regardless of overhang rules. But if the coat-tails rule is abolished, there is an increased risk of overhangs. The method chosen to handle overhangs can disrupt the proportionality of the result.
In general, overhangs arise when a party or independent candidate win electorate seats, but the St Lague system allocates them fewer seats.
There are several main ways this can happen:
- A dominant party overhang occurs when a large and dominant party wins more seats than its party votes justify. This happens frequently in other countries, but is very unlikely in New Zealand. Conceptually this type of overhang could occur where a party is very dominant only within a small region, but such situations have not yet occurred in New Zealand.
- A vote-splitting overhang occurs when voters vote for a candidate for one party and give their party vote to another party. This has occurred in NZ when voters have voted for Maori party electorate candidates and given their party vote to the Labour Party. This practice could theoretically be practised widely, so gaming the system and greatly distorting proportionality,
- A threshold-driven overhang occurs only in the absence of the present coat-tails rule. It occurs when a party wins an electorate seat, but not enough votes to pass the 5% threshold.
In reality there are overlaps between these types of overhangs, so that rules are needed that work in a wide variety of circumstances.
The threshold driven overhang occurs only if the present coat-tails rule is abolished. In New Zealand there have been several situations where MPs have resigned from major parties and created their own party. This type of situation demonstrates an inconsistency between handling of elecorate and party votes. Independents can be lone voices in parliament, while parties are allowed only if they can get to six seats (5% of 120).
At present when an overhang occurs the party or candidate is allocated a seat over and above the normal 120 seats in parliament, and the proportionality of parliament is disturbed.
Another method of handling overhangs is to take the overhang seats from the seats otherwise allocated to list votes, so avoiding extra seats in parliament. Proportionality is disturbed, but often not greatly in NZ, as the overhang seats are taken from parties approximately in turn, and in proportion to their party votes.
This method is used in a similar electoral system in Scotland. There the overhangs are mostly of the dominant party type. As a result the overhang seats are effectively taken from other parties to give to the dominant party, so substantially disturbing proportionality.
The use of a second choice of party vote does not alter the overhang problems outlined above. Dominant party overhangs are unlikely in NZ and not serious, so can be safely disregarded.
A better treatment is needed of overhangs resulting from independents without supporting party votes. It is complicated by the ideal of representation i proportional to party votes whereas an independent has not party votes.
And the solution needs to work around the inconsistency between allowing single seats for independents, but refusing representation for parties with less than 5% of the national party vote.
Here is a sugestion that could largely eliminate the overhang problem. But I need to look more closely to be sure.:
- in electorate contests, there will be one winner. typically in NZ with 12-20k votes.
- All voters who gave their electorate vote to this winner , will have their party vote redirected to that winner s party. For an independent, the party is just the candidate them selves. The winner will receive one seat from their party s allocation, irrespective of the quotient.
This method should ensures that an electorate winner receives approximately the normal quota of party votes for their seat, and uses them to gain a seat.
In this way every seat requires a quota of party votes. And there is only a limited total quantity in the election.
This system makes vote counting more complex, because it is necessary to keep a total for every combination of party vote and candidate vote.
So there are things to check here. Does this work in every likely circumstance? How would you organise vote counting?
Based on a small sample, when there are about 40 000 votes, with two major candidates, the winner gains at least about 19 000 votes. With three major candidates, the winner often received about 13 000 votes. A typicalNZ general election has 72 electorates each with 40 000 votes on average. That means 40 000 electorate votes and 40 000 party votes. This corresponds to 2.88 million votes. If a candidate wins on 13 000, there will normally be two others at about 12 000 each , and about 3 000 among other parties.
More information to come