[EM] Continuous bias

[Juho Laatu]

The final of the Eurovision Song Contest of this year was held last saturday. In the vote all countries give points to the songs of all other countries (that made it to the final). The voting traditions are a bit biased. Countries tend to give high points to their neighbours or otherwise similar countries. Countries are not allowed to vote for themselves, but minorities living or working in some country may have considerable impact since they may have sympathies also towards some other country. All this means that in addition to voting for good songs people vote also for their best friends. Eurovision Song Contest is a friendly competition though, and a major carnival, and people don't worry too much about this kind of (well known) voting patterns. Maybe they are just part of the fun and even one essential part of the competition. But as a person interested in voting I started wondering if this kind of voting patterns could be fixed or eliminated.

The winner is chosen using a Borda like method. Each country gives points to 10 songs that they consider best. Those songs are given 12, 10, 8, 7, 6, 5, 4, 3, 2 and 1 points. In the final there have been 25 or 24 songs, so all the remaining songs will get 0 points. Then the points are summed up and the song/country with most points wins.

I compared the number of points that each country gave to each other country to the average number of points that that country got. After checking few previous years the patterns were quite obvious. The basic fix to the problem could be such that if country A gives on average k times as much points to country B than others do, then the points given by country A to country B in the next election will be divided by n. One could make this function also softer in the sense that one would not reduce the points that much, or one would put higher weight on the few last years only, or giving low points once would be considered a proof that the pattern is not systematic (and that would reduce the factor more that giving high points increases it). But I guess the basic idea is clear. Systematic positive bias leads (in the next election) to reduction in the points that A gives to B. (Negative bias may not be that relevant.)

This Eurovision Song Contest vote is a Borda like election, but this approach would work as well and better also for Range like elections. One could rig it for ranked elections too (e.g. in a pairwise comparison table based Condorcet method one vote could add only 1/k votes in the some comparison table entry).

Would this approach maybe be useful and practical somewhere? What other approaches there are to eliminate this kind of systematical bias?

Juho



P.S. The highest factors that had lasted systematically for several years were somewhat above 10. I.e. some countries gave systematically 10 times as many points to some other countries than others did. (Since countries participating in the competition and countries that make it to the final are not always the same, the results can not be computed for all country pairs for every year. Therefore I required some minimum number of entries (possibility of A giving points to B) (e.g. 3 or 4) to count the factor for some pair of countries.)