GEOFF DAVIES. Score voting: a simpler, less distorting measure of voters’ will

Jan 3, 2018

Score voting avoids the vagaries and gaming that are intrinsic to preference ranking systems. It is simpler and more reliably reflects the will of voters. You have probably used it if you have completed a survey. We should use it in political elections. 

The 2018 Victorian election has turned up another result in which ‘preference whispering’ by minor parties has distorted the will of the people ($, William Bowe at Crikey), if we take the will of the people to be indicated by first-preference votes.

Minor parties scored 25% of upper house seats from 20% of first-preference votes, whereas the Greens scored only one seat with votes that exceeded almost all minor-party votes individually. In one case a primary vote of 1.3% beat a Greens primary vote of 13.5%.

A Senate election in WA a few years ago hung on the chance flow of minor preferences halfway through the count. A slightly different flow would have swung the count to a different winning candidate, though the key preferences were not directly about that candidate.

Voting systems in some states and federal elections were reformed a few years ago to reduce this kind of distortion. The trouble is there is no perfect preferential voting system. Preferential voting is intrinsically prone to such distortions. There is even a mathematical theorem proving it can never be guaranteed to accurately reflect the will of the people.

There is however another voting system that is much less prone to distortion, and to the associated gaming commonly used to deflect voters’ intentions. It is called, variously, score voting, range voting or utilitarian voting.

You have probably used this system, just not in elections. It is used commercially to measure the popularity of products. It is also commonly used to determine voters’ approval of the performance of prime ministers and other politicians, and sometimes to choose among different policies.

This is the kind of survey in which you might be asked, about each alternative, whether you approve, disapprove or don’t care. The surveyor assigns a score to each option, such as +1, -1, and 0, and simply adds up the scores for each alternative. Sometimes the scale is extended to include strongly approve (+2) and strongly disapprove (-2).

So in an election a ballot paper would list all the candidates and ask you to rate each candidate. You could assign your score or degree of approval to any or all candidates. The candidate with the highest tally of scores would be the winner. If there were, say, five candidates to be elected then the five highest scorers would be elected.

This system has many advantages, the main one being it is simple and only minimally distorts the will of voters. There would be little opportunity to game the system because there are no flows of preferences that can be manipulated, simply a tally of scores.

There would be no such thing as an informal vote, because if you did not rate a candidate it would be taken to mean “don’t care”.

If you were equally comfortable with two candidates, you could give them both your full approval, and they would both benefit. If you wanted to maximise the chances of one candidate, you could give them maximum approval and all the others maximum disapproval. Conversely if you wanted to minimise the chances of a candidate you could give them maximum disapproval and all the others maximum approval.

There would be another important benefit. If all parties were very unpopular, as has been true in Australia for some time, then that would show up in the scores. For example a winning candidate might get an average score of only -1, and the other candidates -1.5 or less. In that case it would be clear that voters had chosen the least undesirable candidate, rather than one of whom they really approve.

Winning politicians love to claim they have a mandate for all their policies. It’s never that simple of course, but with this system you would have objective evidence they had not been “approved”, just tolerated as the least-worst alternative.

There is a web site that explores the details and nuances of score voting, run by the Center For Election Science in the US. One version, in which you simply either approve or disapprove, is called approval voting.

Technically it is called a cardinal voting system, as distinct from an ordinal voting system. You rate each candidate rather than putting all candidates in rank order. You can express your absolute level of approval, not just your “approval” of a bad candidate relative to worse candidates.

So let’s have ballot papers that survey our rating of candidates, elections that simply and straight-forwardly choose the highest-rated, or least-low-rated, candidates, and results that register our collective degree of approval or disapproval.

 Dr. Geoff Davies is a commentator, scientist and author of Desperately Seeking the Fair Go, among other books.  He blogs at BetterNature Books .

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